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There is a new empirical turn in international legal scholarship. Building on decades of theoretical work in law and social science, a new generation of empirical studies is elaborating on how international law works in different contexts. The theoretical debate over whether international law matters is a stale one. What matters now is the study of the conditions under which international law is formed and has effects. International law is the product of specific forces and factors; it accomplishes its ends under particular conditions. The trend toward empirical study has expanded through the efforts of scholars in multiple disciplines, with legal scholars playing central roles independently and as collaborators in generating new empirical work. Legal scholars are also now pressed to be increasingly sophisticated consumers of this work. It is time to take stock and evaluate this new generation of multidisciplinary, multimethod empirical scholarship.
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University of Minnesota
Law School
Legal Studies Research Paper Series
Research Paper No. 12-09
The Empirical Turn in International
Legal Scholarship
Gregory Shaffer
Tom Ginsburg
This paper can be downloaded without charge from the Social Sciences
Research Network Electronic Paper Collection at
Electronic copy available at:
Forthcoming: vol. 106: 1 AMERICAN JOURNAL OF INTERNATIONAL LAW 1 (January 2012)
Please consult the published text for the final version of this article.
There is a new empirical turn in international legal scholarship. Building on decades of
theoretical work in law and social science, a new generation of empirical studies is elaborating
on how international law works in different contexts. The theoretical debate over whether
international law matters is a stale one. What matters now is the study of the conditions under
which international law is formed and has effects. International law is the product of specific
forces and factors; it accomplishes its ends under particular conditions. The trend toward
empirical study has expanded through the efforts of scholars in multiple disciplines, with legal
scholars playing central roles independently and as collaborators in generating new empirical
work.1 Legal scholars are also now pressed to be increasingly sophisticated consumers of this
work. It is time to take stock and evaluate this new generation of multidisciplinary, multimethod
empirical scholarship.
The empirical turn is not atheoretical, but it generally is not aimed at building grand
metatheory. Instead, it focuses on midrange theorizing concerning the conditions under which
international law (IL) is formed and those under which it has effects in different contexts, aiming
to explain variation. We thus call it conditional IL theory. By building theory from empirical
study, it involves what one of us has called an “emergent analytics”—that is, analytics that
oscillate between empirical findings, abstract theorizing, real-world testing, and back again.2 In
this way, scholars help narrow the gap between abstract theory, empirical research, and the world
of practice. Theoretical engagement becomes part of a dynamic, recurrent, interactive process
with empirical assessment of international law in action. As social theorist Robert Merton wrote,
“empirical research goes far beyond the passive role of verifying and testing theory: it does more
than confirm or refute hypotheses. Research plays an active role: . . . It initiates, it reformulates,
it deflects, and it clarifies theory.”3
* Respectively, Melvin C. Steen Professor of Law, University of Minnesota; and Leo Spitz Professor of International
Law, University of Chicago, and Research Professor, American Bar Foundation. The authors thank Karen Alter,
Chad Bown, Marc Busch, Tim Büthe, Peter Cane, Christopher Drahozal, Herbert Kritzer, Jonathan Nash, Hari
Osofsky, Mark Pollack, Tonya Putnam, Beth Simmons, and Christopher Whytock for helpful comments, and Ryan
Griffin, Youssef Kalad, Claudia Lai, Kristen McKeown, Mary Rumsey and Carolyn Tan for excellent research
1 This recognition was manifested in the American Society of International Law’s award of its 2010 book prize to
Beth Simmons’s pathbreaking empirical study of international human rights law. BETH A. SIMMONS, MOBILIZING
Annual Meeting was the first to include a panel, “Empirical Approaches to International Law,” specifically
addressing this new direction in international legal scholarship. The Society’s executive director participated.
2 See Victoria Nourse & Gregory Shaffer, Varieties of New Legal Realism: Can a New World Order Prompt a New
Legal Theory, 95 CORNELL L. REV. 61 (2009).
3 ROBERT K. MERTON, SOCIAL THEORY AND SOCIAL STRUCTURE 157 (1968) (emphasis omitted); see also AVNER
role of theory in an interactive, theoretically informed, context-specific analysis”).
Electronic copy available at:
The shift toward the empirical study of international law is not completely new, to be
sure. The new generation of social-science approaches to the study of international law has its
echoes in an earlier tradition of skeptical and functional international legal scholarship.4 It has its
forebearers, to a certain extent, in the New Haven School of policy science of Myres McDougal
and Harold Lasswell,5 which grew out of American legal realism (although that school was
critiqued for not following up on the empirical work that it prescribed),6 and some work of the
legal process school, such as that of Abram and Antonia Chayes.7 More generally, since
international legal scholars have long been concerned with enhancing the effectiveness of
international law, they have been particularly attuned to case studies of international law’s role.8
It is nonetheless fair to say that much of traditional international legal scholarship
focused on formal law and normative prescription, paying special attention to the International
Court of Justice (ICJ). This scholarship tended to assume, rather than examine, the efficacy of
international law and cooperation, and to bemoan instances in which international legal
institutions were unable to constrain power or affect domestic practice. A search through all the
4 As Hans Morgenthau aptly put it in 1940, in the legal realist tradition,
[t]he science of international law, as well as the social sciences in general, are still awaiting their
Newton, their Leibniz, their Faraday, their Carnot, their Maxwell, and their Hertz. To expect the
contemporaneous lawyer to be an “engineer” or “technician” of the law means to expect Edison
before Faraday, Wright before Carnot, Marconi before Maxwell and Hertz. And this is certainly a
futile expectation. The great task which lies before the social sciences is to prepare the work of the
latter so that the former can build upon it.
Hans Morgenthau., Positivism, Functionalism and International Law, 34 AJIL 260, 284 (1940); see also
TRENDS (1971); Wolfgang Friedmann, Some Impacts of Social Organization on International Law, 50 AJIL 475
(1992) (noting that, for them, “the most viable conception of law . . . as revived by the American Legal Realists [is]
that of a process of authoritative decision by which the members of a community clarify and secure their common
interests”); Myres Smith McDougal, Law and Power, 46 AJIL 102 (1952).
6 See, e.g., Gray Dorsey, Agora: McDougal-Lasswell Redux: The McDougal-Lasswell Proposal to Build a World
Public Order, 82 AJIL 41, 49 (1988) (“Julius Stone pointed out that in none of these studies did McDougal and
associates make the comprehensive empirical investigation that they specify for the scholars who are charged with
building the world public order.” Citing JULIUS STONE, VISIONS OF WORLD ORDER 29 (1984)); Oran R. Young,
International Law and Social Science: The Contributions of Myres S. McDougal, 66 AJIL 60, 63 (1972) (“[I]t is
hardly surprising that McDougal is a great advocate, at least at the verbal level, of expanding the use of findings
from the social sciences in legal analysis. What is somewhat surprising, however, is that McDougal’s substantive
contributions to the achievement of this objective are not particularly impressive and that the opportunities for
introducing findings from the social sciences far outdistance their actual introduction in his own work.”).
8 See W. Michael Reisman, International Incidents: Introduction to a New Genre in the Study of International Law,
10 YALE J. INTL L. 1 (1984) (but critiquing mainstream international legal scholarship for focusing on the fantasy
world of “cases” rather than on “incidents” in which law plays a normative role without states bringing a matter
before a court).
volumes of the American Journal of International Law shows that until the last few years (after
the AJIL’s centennial issues), the AJIL published little to no empirical work.9
The tendency, until recently, for international legal scholarship to be somewhat aloof to
empirical methods is reflected in the concept of “method” used in the AJIL’s 1999 Symposium
on Method in International Law. Not one contribution in the symposium addressed method in a
social science sense, suggesting a significant gap between legal and social science scholarship.
Rather, the alternative “methods” all involved theoretical and analytical claims. The introductory
essay of the symposium issue, “A Prospectus for Readers,” first distinguished method (or
analytic frame) from what it called “methodology,” noting (from a legalist perspective) that
“methodology of legal research” consists of the “ways to identify and locate primary and
secondary resources.”10 The essay then introduced seven theoretical and analytic frameworks,
each of which was represented in one of the subsequent articles, which covered “legal
positivism,” international relations (IR) theory, law and economics, the Yale school of “policy-
oriented jurisprudence,” the “new international legal process,” critical reflections, and feminist
methods, respectively.11 The issue concluded with an essay entitled “The Method is the
For social scientists, however, theory (or analytic framework) and method are distinct,
although interrelated inquiries. Rather than understanding “method” as “message,” social
scientists view method as the use of methodological tools to assess how, and under what
conditions, international law works in practice. Theory, in other words, must not supplant the
rigorous empirical examination of practice, and thus the testing of theory. From the perspective
of conditional IL theory, the topics addressed by the theories of earlier generations are best
pursued through midlevel, empirically grounded work regarding particular international law
For purposes of this article, empirical work involves the systematic use of qualitative or
quantitative methods. While some references to an empirical turn in legal scholarship appear to
refer to only quantitative work, ignoring work using other empirical methods, we consciously
aim to be more ecumenical in our coverage.13 We thus do not limit our review and assessment to
9 But see, e.g., Samuel A. Bleicher, The Legal Significance of Re-citation of General Assembly Resolutions, 63 AJIL
444, 455, 477 (1969) (presenting tables of frequency of citation of General Assembly resolutions); Kathryn B.
Doherty, Rhetoric and Reality: A Study of Contemporary Official Egyptian Attitudes Toward the International Legal
Order, 62 AJIL 335, 335–36 (1968); John King Gamble, Reservations to Multilateral Treaties: A Macroscopic View
of State Practice, 74 AJIL 372 (1980); Richard H. Steinberg, Trade-Environment Negotiations in the EU, NAFTA,
and WTO: Regional Trajectories of Rule Development, 91 AJIL 231(1997) (using, for example, a logistic regression
to assess implementation of European Union environmental directives).
10 See Steven R. Ratner & Anne-Marie Slaughter, Appraising the Methods of International Law: A Prospectus for
(1984)). The authors likely meant to use the term “sources,” which is that used by Rosenne. Ratner and Slaughter
distinguish “methodology” from “method.” They cite Philip Allott for the proposition that “methods . . . refer to the
structure of their argumentation, in particular its logical discourse.” Id. at 292.
11 This symposium issue was followed by an edited volume entitled The Methods of International Law, in which a
new contribution was added that addressed Third World approaches to international law. See Antony Anghie & B.S.
Chimni, Third World Approaches to International Law and Individual Responsibility in Internal Conflict, in THE
METHODS OF INTERNATIONAL LAW 185 (Steven R. Ratner & Anne-Marie Slaughter eds., 2004).
12 See Anne-Marie Slaughter & Steven Ratner, The Method Is the Message, 93 AJIL 410 (1999).
13 See generally Elizabeth Mertz & Mark Suchman, A New Legal Empiricism: Assessing ELS and NLR, 6 ANN. REV.
L. & SOC. SCI., 555 (2010) (comparing the “empirical legal studies” movement with its journal, the Journal of
systematic work based on causal inference, although we highlight work in this vein. Rather we
include references to work using ethnography/participant observation, systematic interviewing,
historical process tracing, analytic narratives, surveys, content analysis, and large-N, quantitative
statistical analysis. These various methods are sometimes privileged by particular disciplines,
such as anthropology, economics, geography, political science, and sociology, but each of them
offers a particular perspective on international law in action.
Empirical work is conventionally divided into studies using quantitative and qualitative
methods, each of which has its strengths and deficiencies, thus involving tradeoffs. In many
cases, scholars take multimethod approaches that combine quantitative and qualitative methods
to support their claims. Since the relative advantages have been assessed elsewhere,14 we will
summarize briefly as follows.
The power of quantitative methods is an ability to test hypotheses in a rigorous manner
against large quantities of data using statistical techniques and control variables. The major
challenges for these methods involve measurement and causal inference. Reducing complex
social realities to indicators and measures that can be used in statistical analysis is often difficult.
Furthermore, even if measurement challenges can be resolved, producing a research design to
draw causal inferences can involve as much art as science. Quantitative methods, however, do
allow the use of more refined data-collection techniques and control variables to help to
determine the relevance of different factors in explaining international law developments and
their impact.
Qualitative work, by contrast, offers the advantage of paying closer attention to dynamic
social contexts, as it often involves field work and interviews. One challenge is that the findings
from qualitative work tend to be less generalizable because they are context specific. Yet what
these studies lose in terms of parsimony (that is, in terms of causal inference that is clearly
specified, and thus can be formulated in an equation and tested statistically) also makes them
more grounded in specific social contexts that numerical data do not adequately capture. In
addition, qualitative work may be viewed as untrustworthy because it reflects the normative
predispositions of the observer or those the researcher interviews. However, techniques are
available to help control for researcher bias. One such method is triangulation, which enables the
researcher to “compare[] different kinds of data from different sources to see whether they
corroborate each other”;15 for example, the researcher can interview those who have opposing
interests in respect of the issue at stake, and who come from different backgrounds, and can
combine interviews with ethnographic observation, while consciously aiming to retain a neutral
perspective from a reflective distance. Venturing into the field to conduct qualitative research,
moreover, provides a concrete opportunity to assess one’s presuppositions.
Empirical Legal Studies, which is almost exclusively quantitative, and the “new legal realist” movement, which is
more ecumenical).
15 See RESEARCHING SOCIETY AND CULTURE, supra note 14, at 231.
The use of quantitative or qualitative methods will often depend on the question posed.
Quantitative approaches will be relatively more pertinent for macro-questions, such as the impact
of a WTO judicial decision on imports,16 the effect of human rights law on human rights
practices,17 or the impact of bilateral investment treaties on investment.18 Qualitative approaches
are especially well suited for assessing the mechanisms of behavioral change, allowing the
researcher to understand the particular channels through which legal rules affect individuals,
organizations and states. Qualitative work is also important for generating theory that
quantitative work can test.
Notwithstanding the relative benefits of these methodological tools, the international
arena presents special methodological challenges and also sometimes requires distinctive
research strategies (to be discussed later). Overall, the current, new wave of international legal
scholarship takes the reach and efficacy of international law as empirical matters to be assessed.
They are to be neither assumed (as in traditional doctrinal scholarship) nor explained away as
unimportant (as in the realist tradition of IR).
This article is organized in five parts. Part I assesses the reasons for, and evidence of, the
current empirical trend, some critiques of this trend, and responses to those critiques. Part II
examines cross-cutting studies of the growing empirical literature on international treaties and
tribunals. In addition to discussing some work that focuses on particular tribunals, we introduce
some broader work on the choice of legal instruments and the operation of tribunals—which
helps set the stage for part III.
Part III turns to five discrete substantive areas of international law: international human
rights law; criminal law and the law of war; trade law; investment law; and environmental law.
These areas are selected to be broadly representative, though we recognize others could be
included just as well. In each case we address what is distinctive about each problem area—a
crucial step for conditional IL theorizing—and survey and assess the state of empirical work in
that area. We focus on two organizing questions: (1) how is international law produced, and (2)
under what conditions does international law matter? Broadly speaking, the first question
engages the causes of, and influences on, international legal phenomena, whereas the second
addresses consequences. By disaggregating our review of international law into different
functional domains organized under these two questions, we can highlight and explain both
variation and patterns that shed light on critical normative questions.
Drawing from our survey and analysis of empirical scholarship, part IV and the
conclusion represent a preliminary effort to construct a conditional IL theory regarding how, and
the conditions under which, international law works. It highlights the importance of work that
mediates between theory building and the empirical assessment of practice. Such work, we
contend, is central for addressing the normative issues at stake.
What explains the empirical trend in the study of international law? This scholarly trend,
16 See Chad Bown, On the Economic Success of GATT/WTO Dispute Settlement, 86 REV. ECON. & STAT. 811
17 See SIMMONS, supra note 1, and part III on Human Rights
18 See part III on International Investment Law.
in our view, is driven by the increased role of international law in global governance and, in turn,
by the increased attention that other disciplines have given to international law as a subject of
study. The end of the Cold War, the fall of the Berlin Wall, and economic and cultural
globalization have created new demand for international law and facilitated its realization. The
proliferation of international law, in other words, can be viewed as the product of a changed
structural context, greater ideological convergence, and greater functional need.
These developments in the world spurred developments in social science theory, with
renewed interest in international law. The previous dearth of empirical work on international law
reflected, in particular, the enduring importance of the realist tradition in IR scholarship. For
classical and structural realists, state power determines outcomes on the international stage, and
international law is “epiphenomenal,” deemed to have no independent causal impact on
outcomes.19 While realism is still an important paradigm and has been applied forcefully to
international law in recent years,20 the mainstream of IR scholarship now reflects the rational
choice, institutionalist tradition associated with Robert Keohane and the constructivist insights
associated with John Ruggie and Alexander Wendt.21
Under both rational choice and constructivist theories, international law plays potentially
important roles that merit careful empirical inquiry. In the rational institutionalist paradigm,
international institutions facilitate state cooperation by reducing the transaction costs of
negotiating international agreements with multiple parties, and by promoting compliance with
them through monitoring and enforcement.22 This work has complemented that of economists,
who have begun to study the role of institutions at the international level, whether to understand
and improve the supply of global public goods23 or to facilitate the resolution of other
cooperation and coordination challenges.24 Constructivists, by contrast, focus on the role of
international institutions in exercising normative power and in shaping states’ and other actors’
perceptions of problems, solutions, and interests.25 In other words, under rational institutionalist
theory, international law serves critical functional purposes, and under constructivist theory, it
wields normative authority. In both cases, these theories validate the promise of international law
to shape world order.
Sociologically oriented approaches to law and globalization, such as world polity,
postcolonial, and law-and-development theory, also have been increasingly influential in
international legal scholarship, in parallel with IR approaches.26 World polity theory addresses
19 See Richard Steinberg & Jonathan Zasloff, Power and International Law, 100 AJIL 64 (2006).
position, see Steinberg & Zasloff, supra note 19.
POLITICS (1999); John G. Ruggie, What Makes the World Hang Together? Neo-utilitarianism and the Social
Constructivist Challenge, 52 INTL ORG. 855 (1998).
22 Emilie M. Hafner-Burton, David G. Victor & Yonatan Lupu, Political Science Research on International Law:
The State of the Field, 106 AJIL 000 (2012).
Goulven & Ronald U. Mendoza eds., 2003); TODD SANDLER, GLOBAL COLLECTIVE ACTION (2004).
25 See, e.g., Martha Finnemore & Stephen J. Toope, Alternatives to “Legalization”: Richer Views of Law and
Politics, 55 INTL ORG. 743, 743 (2001).
26 For a nice overview, see Terence Halliday & Pavel Osinsky, Globalization of Law, 32 ANN. REV. SOC. 447
how international legal scripts operate as conveyors of globalized cultural norms, leading to
convergence and thus compliance. The world polity approach has been empirically developed by
the sociologists John Meyer, John Boli, and Elizabeth Boyle, among others, regarding human
rights and neoliberal economic issues, and has been used to support theory building in
international law by Ryan Goodman and Derek Jinks.27 Postcolonial theory examines the
interaction of global legal norms and domestic systems in developing countries and has been
studied empirically using ethnographic methods by anthropologists, such as Sally Merry
regarding women’s rights issues, both at the international and domestic levels.28 In addition,
socio-legal scholars have empirically studied the diffusion of legal models through international
institutions, contributing to law-and-development theory.29
In view of the increasing number of articles on international law topics published in
flagship journals of the various social sciences, it is evident that these disciplines are giving ever
more attention to international law. To provide a sample of this trend across disciplines, we
reviewed all of the publications from 1980 to 2010 of International Organization, the flagship
journal in the discipline of IR; Law and Social Inquiry, the flagship journal published by the
American Bar Foundation for the multidisciplinary study of law, with a particular emphasis on
the sociology of law; and the Journal of Legal Studies, a flagship journal for the
multidisciplinary study of law that focuses on law and economics.30 International Organization
published a single article on law and courts in the 1980s, but twenty-six in the 2000s,
constituting 9 percent of all articles published during the decade.31 Law and Social Inquiry
increased its publication of articles on international and transnational law topics over fourfold
during those same periods, from 2.2 percent (1980–90) to 10 percent (2000–10) of the total
articles published in the journal. We see an even more dramatic trend at the Journal of Legal
Studies, which did not publish an article on international law before 2000 (though it did include a
small number of comparative law articles) but published twenty-four in the 2000s.32 We note this
data to show, in particular, the increased attention that these disciplines give to international law.
27 See John W. Meyer, The World Polity and the Authority of the Nation-State, in STUDIES OF THE MODERN WORLD-
SYSTEM 109 (Albert J. Bergesen ed., 1980); Martha Finnemore, Rules of War and Wars of Rules: The International
Red Cross and the Restraint of State Violence, in CONSTRUCTING WORLD CULTURE: INTERNATIONAL
NONGOVERNMENTAL ORGANIZATIONS SINCE 1875, at 149 (John Boli & George M. Thomas eds., 1999); ELIZABETH
INTO LOCAL JUSTICE (2006). Third World Approaches to International Law come out of postcolonial studies and
include the work of ASIL’s 2010 Grotius Lecturer, Antony Anghie. ANTONY ANGHIE, IMPERIALISM, SOVEREIGNTY
ECONOMIC DEVELOPMENT 1960–1995 (1999).
30 Data is available in an online appendix at
31 The number of articles on treaties more than tripled during the same period, and the combined percentage of
articles on law and treaties increased over fivefold from 4.32 percent (1980–89) to 10.88 percent (1990–99) to 22.91
percent (2000–09).
32 The Journal of Law, Economics and Organization, the other law and economics journal with a strong empirical
focus, has been less willing to publish international law articles, with less than 1 percent (2 of 233) articles on the
topic published since 2000, and none beforehand.
Yet our review of this work also confirms that much of it is empirical and uses quantitative and
qualitative methods to assess how international law works in practice.
Although the empirical trend of scholarship on international law first developed primarily
outside of traditional law reviews, it has since migrated into them, including the American
Journal of International Law. In the 1990s and 2000s, AJIL increasingly published articles and
book reviews that challenged international law theories and prescriptions for their lack of an
empirical basis, and that called for sustained empirical analysis.33 Since 2007, AJIL has
published an increasing number of original empirical studies, of which we count at least six.34
In many cases, legal academics are engaging in cross-disciplinary collaborations. Legal
scholars bring greater internal knowledge of how particular international legal institutions
33 For an excellent piece using empirical support, see Steinberg, supra note 9. A brief sampling of such calls for
empirical work includes Jeffrey L. Dunoff & Joel P. Trachtman, Symposium on Method In International Law: The
Law and Economics of Humanitarian Law Violations in Internal Conflict, 93 AJIL 394, 394–95 (1999) (“While law
and economics is rich in theory, it exalts empiricism (in which it is surprisingly poor).”); Thomas M. Franck,
Centennial Essay in Honor of the 100th Anniversary of the AJIL and the ASIL: The Power of Legitimacy and the
Legitimacy of Power: International Law in an Age of Power Disequilibrium, 100 AJIL 88, 96 (2006) (“To address
that issue, it becomes necessary to resort to a kind of legal empiricism: to ask how many states, in how many
situations of disputation, currently discredit the law pertaining to the use of force in word and deed?”); and Kal
Raustiala, Form and Substance in International Agreements, 99 AJIL 581, 605–06 (2005) (“No matter which
theoretical approach one favors, the empirical impact of different structures should be understood. Yet the dearth of
research on this topic makes any such claims tentative.”). For an earlier critique in a similar vein, see Gordon B.
Baldwin, Book Review, 57 AJIL 976 (1963) (reviewing INTERNATIONAL CONTRACTS: CHOICE OF LAW AND
LANGUAGE) (“International law study today suffers from the scarcity of empirical research.”). We find increasing
calls for empirical work particularly in reviews of books on international law. See also José E. Alvarez, Book
LAW (2007)) (“Also missing is any more general empirical effort to demonstrate such bias in the many public
arbitral decisions issued to date.”); Daniel Bodansky, Book Review, 99 AJIL 280, 283 (2005) (reviewing EYAL
(“Like most international lawyers, however, Benvenisti appears more comfortable with legal doctrine than with
systematic empirical research.”); Jide Nzelibe, Book Review, 103 AJIL 619, 620 (2009) (reviewing JOEL
TRACHTMAN, THE ECONOMIC STRUCTURE OF INTERNATIONAL LAW (2008)) (“[Trachtman] cautions that many of his
empirical assumptions about how states behave should not be taken at face value. Throughout the book he frets
about the need to subject his principal claims, as well as those of competing approaches, to rigorous empirical
testing.”); Beth A. Simmons, Book Review, 103 AJIL 388, 391 (2009) (reviewing MARY ELLEN O’CONNELL, THE
POWER AND PURPOSE OF INTERNATIONAL LAW (2008)) (“This last claim is tough to sustain empirically, and while it
is asserted vigorously in the critique of Goldsmith and Posner and restated in various ways throughout the book,
evidence of the impact of legal rules and justifications on behavior is not systematically adduced.”).
34 Since 2007, this Journal has published Frans Viljoen & Lirette Louw, State Compliance with the
Recommendations of the African Commission on Human and Peoples’ Rights, 1994–2004, 101 AJIL 1 (2007). See
also Laurence R. Helfer, Karen Alter & M. Florencia Guerzovich, Islands of Effective International Adjudication:
Constructing an Intellectual Property Rule of Law in the Andean Community, 103 AJIL 1 (2009); Laura A.
Dickinson, Military Lawyers on the Battlefield: An Empirical Account of International Law Compliance, YES104
AJIL 1, 1 (2010); Laurence R. Helfer, Eugene Kontorovich & Steven Art, An Empirical Examination of Universal
Jurisdiction for Piracy, 104 AJIL 436 (2010); Maximo Langer, The Diplomacy of Universal Jurisdiction: The
Regulating Role of the Political Branches in the Transnational Prosecution of International Crimes, 105 AJIL 1
(2011); Galit A. Sarfaty, Why Culture Matters in International Institutions: The Marginality of Human Rights at the
World Bank, 103 AJIL 647, 649 (2009); Ryan Goodman, Humanitarian Intervention and Pretexts for War, 100
AJIL 107 (2006) (systematically reviewing and synthesizing existing empirical work so as to build empirically
grounded theoretical claims on the law of international humanitarian intervention, and challenging conventional
arguments that legalizing humanitarian intervention will necessarily lead to more, exacerbated international armed
conflicts because humanitarian justifications will be used as pretexts).
operate, and collaborate with social scientists skilled at deploying increasingly sophisticated
empirical tools. These collaborations again reflect both the increased interest of other disciplines
in the study of international law, and the interest of international legal scholars in the methods
used by these other disciplines.35
The increased empirical attention given to international law is also supported by technical
developments and funding opportunities that facilitate data gathering and analysis. A major
development has been the rapid increase in the power of statistical packages. Operations that,
twenty years ago, would have required many hours on mainframe computers can now be
performed in a matter of seconds on individual personal computers. This development has
enabled large-N analyses of ever increasing sophistication and rigor, and has increased demand
for the production of databases. In addition, increased funding opportunities have played a role in
spurring the trend. The National Science Foundation (NSF), whose budget has gone up sevenfold
since 1983, has become a major source of funding for the social sciences.36
Beyond its role in theoretical development, the empirical turn has important normative
advantages. First, as legal realists have long maintained, the empirical study of law helps to
unpack assumptions, whether concerning law’s legitimacy or its benevolent impact. For
example, the legal realists were interested in the biases existing within legal doctrine.37 To
unpack potential bias, scholars have empirically assessed what lies behind international law’s
formation. Second, empirical work has practical implications for international lawyers wishing to
understand what works, permitting them to reassess international law and institutions.
International law’s normativity is aimed at changing behavior, so it only makes sense to assess
international law empirically regarding the conditions of its effectiveness.38
Positivist social scientists have argued that “ought implies can,” and so a thorough,
grounded account of what international law can accomplish under different conditions might
inform our understanding of when and how it ought to be invoked.39 Normative legal arguments
depend on assumptions about the state of the world and the likely outcome of alternative legal
rules. Empirical scholarship provides a set of tools to refine understandings of institutional
design and practice so as to enhance international legal institutions’ effectiveness. Conditional IL
theory nonetheless cautions against simplistic copying of mechanisms from one context or issue
area to another, and thus takes a midlevel orientation that is appropriately cautious in drawing
35 On political science, see Hafner-Burton et al., supra note 22.
36 National Science Foundation, Fiscal Year 2011 Budget Request, at For example, each of us has received multiple NSF grants for
quantitative and qualitative empirical work, providing time and resources for engaging on empirical questions.
37 Nourse & Shaffer, supra note 2.
the issue of effectiveness . . . has resulted from the increasing interaction between international lawyers and political
scientists, as well as the turn toward empiricism in many areas of legal scholarship”).
39 For an interesting assessment of the selective invocation of international law and other norms by the International
Committee of the Red Cross (ICRC), see Steven R. Ratner, Law Promotion Beyond Law Talk: The Red Cross,
Persuasion, and the Laws of War, 22 EUR. J. INTL L. 459 (2011) (building from numerous interviews and a year of
participant observation at the ICRC offices in Geneva).
The empirical project has been the object of strong critiques, most notably for its risk of
reductionism and scientism.40 In international law Martti Koskenniemi has arguably been the
most outspoken. As he writes, “these new realists, in their hubris, believe in the power of their
predictive and explanatory matrices . . . . But since expert systems are no less indeterminate than
law, this move only institutionalizes an anti-political, technical mindset.”41 Critiques also come
from neoconservatives bent on changing underlying contexts. For example, the journalist Ron
Suskind, recalls a response of an administration official:
The aide said that guys like me were “in what we call the reality-based
community,” which he defined as people who “believe that solutions emerge from
your judicious study of discernible reality.” I nodded and murmured something
about enlightenment principles and empiricism. He cut me off. “That’s not the
way the world really works anymore,” he continued. “We’re an empire now, and
when we act, we create our own reality. And while you're studying that reality—
judiciously, as you will—we’ll act again, creating other new realities, which you
can study too, and that’s how things will sort out. We’re history’s actors . . . and
you, all of you, will be left to just study what we do.”42
Certainly, the empirical project is not without its critics (and risks), but that is not to say
that the criticism cannot be met, and strongly. The tremendous human and financial toll of the
second Iraq war can be seen as resulting from the anti-empirical bent of its perpetrators, as well
as the failure to comply with international law and international legal procedures. In response to
critiques from the left that empirical scholarship is reductive and conservative, serving to embed
the status quo, conditional IL theory specifically aims to avoid the reductionism of normative
analysis that fails to look at context. It is grounded in philosophical pragmatism, which maintains
that we intervene in an uncertain world and must assess empirically the impact of previous
interventions and use that information to determine what is desirable and possible in any new
context. 43 To give one example, as Thomas Carothers wrote regarding sanctions applied against
Haiti in the early 1990s, which were intended to advance the development of an international
legal norm of democracy:
The international community's response to the 1991 coup in Haiti is often cited as
an example of the positive new solidarity and forcefulness of the international (or
at least the inter-American) community with respect to democracy. Unfortunately,
40 See, e.g., Nourse & Shaffer, supra note 2, at 117–19 (“[T]here are also the related risks of scientism. . . . One of
the grave dangers of a ‘your science is better than my science’ approach is the risk that it hides important (and
perhaps false) normative claims through the very categories it chooses. . . . If the categories one uses in a study are
themselves biased, inaccurate, or false, then the statistical form will simply add a veneer of legitimacy and power to
what might be entirely false. Eugenics is the classic example of this kind of process.”).
41 Martti Koskenniemi, Constitutionalism as Mindset: Reflections on Kantian Themes About International Law and
Globalization, 8 THEORETICAL INQUIRIES L. 9, 30 (2007); see also Guglielmo Verdirame, Review Essay, ‘The
Divided West’: International Lawyers in Europe and America, 18 EUR. J. INTL L. 553, 558–61 (2007).
42 Ron Suskind, Faith, Certainty and the Presidency of George W. Bush, N.Y. TIMES MAGAZINE, Oct. 17, 2004, at
43 Nourse & Shaffer, supra note 2, at 84-85; 88; 112-121 [pages on pragmatism].
the real effect of that response to date has been to worsen the lives of most
Haitians. . . .
. . . .
The current advocacy of a democracy norm is important in international
law, but it is based on a superficial empirical account of world events. It says, in a
sense, “Look, there is a democratic tide, now here is the new principle of law that
we propose to go with it.” In fact, the reality is much more complex, much more
muddled. A legal analysis must take on the complexities of the empirical reality
and at every turn fold them into the doctrinal analysis, if it is to get beyond a
simple Panglossian view of the world—if it is to avoid being relegated to the long
list of discarded utopian projects that litter the past of international law.44
We need, in other words, conditional IL theory that builds from empirical assessments of
Scholarship develops in cycles.45 In some periods, it may emphasize theory; in others it
may move to a greater focus on empirics. The empirical turn in the study of international law
may be viewed as part of a cycle, yet we believe it will also leave its imprint on the study of
international law. It provides the hope of checking those who fail to take account of empirical
context in invoking or failing to invoke international law.
The new empirical program is sufficiently broad and deep that no one article can survey
it in its entirety. Our approach is to be illustrative rather than comprehensive, while at the same
time identifying themes that engage much of the empirical work. The growing legalization and
judicialization of international politics have led to increased legal ordering and enhanced
cooperation across borders. A foundational question for empirical work, then, is to understand
the modalities of legal ordering. When states choose to cooperate, they have choices over
whether to use a written instrument and, if so, over the form and legal nature of that instrument.
They also have the choice of creating new institutions to develop norms, monitor compliance,
and resolve disputes. In this part we consider cross-cutting empirical work on both the design of
instruments such as treaties and the use of legal institutions such as tribunals, respectively
addressing the “legalization” and “judicialization” of IR. In each case, we note where more
empirical work would be helpful.
44 Thomas Carothers, Empirical Perspectives on the Emerging Norm of Democracy in International Law, 86 ASIL
PROC. 261, 266–67 (1992).
45 David J. Bederman, Book Review, 100 AJIL 490, 490 (2006) (reviewing JOHN YOO, THE POWERS OF WAR AND
PEACE: THE CONSTITUTION AND FOREIGN AFFAIRS AFTER 9/11 (2005)) (“[i]n actuality, of course, we have seen a
cyclical pattern of scholarship in this field”); David M. Trubek & John Esser, “Critical Empiricism” and American
Critical Legal Studies: Paradox, Program, or Pandora’s Box?, 12 GERMAN L.J. 115, 119 (2011) (referring to
“cycles of legal scholarship”).
The Form and Legal Nature of the Instrument: Customary International Law, Treaties, and Soft
States have numerous ways of cooperating; treaties are only one mechanism. Much of
international law traditionally arose not from legal instruments, but through state practice, giving
rise to customary international law, which is state practice under a sense of legal obligation.46
This source of international law has been subject to much theoretical speculation and critique,47
but relatively little empirical work examines the extent and manner in which norms of customary
international law(or, for that matter, general principles of law) are used to inform debates. Many
believe that reference to customary international law is in decline,48 but whether the decline is
only a relative one in relation to treaties—and not an absolute one—has not been empirically
We thus need more empirical analysis of how customary international law is formed and
has effects.49 One strategy may be to focus attention on the briefs of states. Customary
international legal norms are often invoked, but we lack empirical analysis of how often claims
based on them are sustained. Systematic study of the foundations that states assert (especially
with regard to custom) for their legal claims and that tribunals use in reaching their findings
would be helpful and might contribute to more rigor in legal practice. Such an approach requires
tracing the emergence and evolution of particular customary rules, and also attention to those
claims of custom that are not recognized as binding rules. Such work, in turn, might help to
reinvigorate customary law and provide a vantage point for proposing doctrinal modifications.50
Indeed, without any real sense of the scope of use of customary international law, it is hard to
assess its operation and efficacy.
46 See, e.g., Lassa Oppenheim, The Science of International Law: Its Task and Method, 2 AJIL 313, 315 (1908)
(“The rules of the present international law are to a great extent not written rules, but based on custom.”).
47 Cf. ANDREW T. GUZMAN, HOW INTERNATIONAL LAW WORKS 218 (2008) (role of reputation in compliance with
customary international law); Jack L. Goldsmith & Eric A. Posner, Understanding the Resemblance between
Modern and Traditional Customary International Law, 40 VA. J. INTL L. 639, 640 (2000) (challenging the “faulty
premise . . . that CIL . . . influences national behavior”); George Norman & Joel P. Trachtman, The Customary
International Law Game, 99 AJIL 541, 542 (2005) (contending that “CIL rules may modify the payoffs associated
with relevant behavior and thereby affect behavior through self-interest”).
48 Andrew T. Guzman, Saving Customary International Law, 27 MICH. J. INTL L. 115, 119 (2005) (“modern
international relations have made the treaty a more important tool, relative to CIL, than it has been in the past”);
international law has become less important than treaties).
49 For one good study see Roozbeh Baker, Customary International Law in the 21st Century: Old Challenges and
New Debates, 21 EUR. J. INTL L. 173 (2010) (arguing for enhanced role of tribunals in formation of customary
international law). See also Tom Ginsburg, Svitlana Chernykh & Zachary Elkins, Commitment and Diffusion: How
and Why National Constitutions Incorporate International Law, 2008 U. ILL. L. REV. 201 (2008) (discussing the
impact of customary international law in national practice); Cheryl Holzmeyer, Human Rights in an Era of
Neoliberal Globalization: The Alien Tort Claims Act and Grassroots Mobilization in Doe v. Unocal, 43 L. SOC.
REV. 271 (2009) (empirical case study of the impact abroad of invoking customary international law before U.S.
50 Curtis Bradley & Mitu Gulati, Withdrawing for Customary International Law, 120 YALE L.J. 202 (2010). See also
symposium on this issue in 21 DUKE J. COMP. & INTL L. 1 (Fall 2010).
By contrast, the last decade has seen considerable empirical work on treaties. From
existing empirical work, we discern at least five important points. These points regard the (1)
changing nature of international law as reflected in treaties, (2) reasons that states choose
different types of treaties, (3) choice between legally binding treaties and “soft law,” (4)
inclusion of specific types of arrangements in treaties such as flexibility mechanisms and the
delegation of dispute settlement, and (5) impact of treaties compared to other forms of ordering.
First, scholars are documenting the increasing use of international treaties to govern IR,51
which can be viewed as a turn to contract (as opposed to custom and natural law), although
universal treaties such as the UN Charter have also been viewed in constitutional, rather than
contractual, terms.52 The overall number of multilateral treaties registered with the UN secretary
general has increased by 400 percent in “just over two decades.”53 Empirical work has examined
changes in the subject matter of these treaties. John Gamble and colleagues have used a database
of almost six thousand treaties signed over the last 350 years (Comprehensive Statistical
Database of Multilateral Treaties) to document an increasing human-centric turn in treaties, as
international law extends to address individuals and not just sovereign states.54 They and others
also observe an increasing regulatory orientation in international treaties, as lawmaking extends
in scope to most administrative regulatory domains.55 International legal scholars, for example,
have noted greater levels of treaty making in such diverse areas as agro-biotechnology, the
environment, food security, investment, and labor.56
Second, scholars are examining differences in states’ choice between multilateral and
bilateral treaties. Thomas Miles and Eric Posner have created a database of over 50,000 treaties
to examine which states enter into particular types of treaties and their reasons for doing so. They
find that “older, less corrupt and (again) larger states . . . enter into more bilateral treaties and
‘closed’ multilateral treaties,” whereas small states are relatively more likely to join “universal
multilateral treaties.”57 They explain these findings from a rational choice perspective that takes
51 John King Gamble, Charlotte Ku & Chris Strayer, Human-Centric International Law: A Model and a Search for
Empirical Indicators, 14 TUL. J. INTL & COMP. L. 61, 72 (2005) (“The metaphor of a rising tide seems
(Jeffrey L. Dunoff & Joel P. Trachtman eds., 2009).
53 Jonathan D. Greenberg, Does Power Trump Law?, 55 STAN. LAW. REV. 1789, 1790 (2003) (emphasis omitted)
(comparing figures from 1979 to roughly 2002).
54 Gamble et al., supra note 51, at 61–80.
55 Id. at 72 (“there has been a significant expansion in the range of activities governed by multilateral treaties, with
the greatest increase occurring in the economic sphere”); Jacob Katz Cogan, The Regulatory Turn in International
Law, 52 HARV. INTL L.J. 321 (2011).
Franck, Foreign Direct Investment, Investment Treaty Arbitration, and the Rule of Law, 19 PAC. MCGEORGE
GLOBAL BUS. & DEV. L.J. 337, 338 (2007) (“During the past two decades, the number of investment treaties has
tripled.”); Laurence R. Helfer, Understanding Change in International Organizations: Globalization and Innovation
in the ILO, 59 VAND. L. REV. 649, 700 (2006) (noting increase in number of International Labour Organization
agreements); Andy Stewart, Book Note, 43 STAN. J. INTL L. 332, 341 (2007) (reviewing BIOTECHNOLOGY AND
INTERNATIONAL LAW ( Francesco Franciono & Tullio Scovazzi eds., 2006)) (noting the “increase in the number of
treaties addressing food security and agrobiotechnology”).
57 Thomas Miles & Eric A. Posner, Which States Enter into Treaties, and Why? 2 (University of Chicago Law
School, Law and Economics, Working Paper No. 420, 2008).
into account differential benefits and costs, especially the transaction costs involved in joining
different types of treaties. Larger states have more resources at their disposal to devote to treaty
making, and can tailor their commitments to their needs more efficiently.
Third, scholars have addressed the choice of legally binding instruments compared to
informal “soft law” agreements.58 The use of soft law instruments is expanding significantly in
light of the growing role of transgovernmental networks, international organizations, and
nonstate actors, giving rise to what are sometimes called transnational legal arrangements.59
Although numerous interesting case studies involving soft law are available,60 systematic
research regarding their use and effects remains at an early stage. It is worth noting, however,
that Stefan Voigt has recently used a database created by the U.S. Department of State pursuant
to the Case-Zablocki Act to assess the use of “informal international agreements,” which, under
the act, are those that do not involve approval by the U.S. Congress.61 Based on a database of
2289 informal agreements concluded by the United States between 1981 and 2010, he finds the
following: the number of informal agreements increased dramatically from the mid-1990s
through 2006, but has since dropped significantly; roughly two-thirds of these agreements
concern only three policy areas (the military, science and technology, and aid); over 90 percent
of these agreements are bilateral; and around 40 percent are concluded by a U.S. actor other than
the president or secretary of state. He also finds that these agreements were especially common
with bordering states, which he suggests is due to the greater frequency of interaction with them.
58 Kenneth Abbott & Duncan Snidal, Hard and Soft Law in International Governance, 54 INTL ORG. 421 (2000);
Gregory C. Shaffer & Mark A. Pollack, Hard vs. Soft Law: Alternatives, Complements and Antagonists in
International Governance, 94 MINN. L. REV. 706 (2010).
59 Cf. Kenneth W. Abbott & Duncan Snidal, Strengthening International Regulation Through Transnational New
Governance: Overcoming the Orchestration Deficit, 42 VAND. J. TRANSNATL L. 501 (2009); Gregory Shaffer,
Transnational Legal Process and State Change: Opportunities and Constraints, LAW & SOC. INQUIRY (forthcoming
2012), available at On the role of actors other than
states, see ANNE-MARIE SLAUGHTER, THE NEW WORLD ORDER (2004); Jose Alvarez, International Organizations:
Then and Now, 100 AJIL 324 (2006); Benjamin Cashore, Elizabeth Egan, Graeme Auld & Deanna Newsom,
Revising Theories of Non-state Market Driven (NSMD) Governance: Lessons from the Finnish Forest Certification
Experience, 17 GLOBAL ENVTL POL. 1 (2007); Errol Meidinger, Multi-interest Self-Governance Through Global
ECONOMIC TRANSACTIONS 259 (Olaf Dilling, Martin Herberg & Gerd Winter eds., 2008); and Kal Raustiala, The
Architecture of International Cooperation: Transgovernmental Networks and the Future of International Law, 43
VA. J. INTL L. 1 (2002).
SYSTEM (Dinah Shelton ed., 2004); John J. Kirton & Michael J. Trebilcock, Introduction: Hard Choices and Soft
ENVIRONMENT AND SOCIAL GOVERNANCE 3, 9 (John J. Kirton & Michael J. Trebilcock eds., 2004); Steven R.
Ratner, Does International Law Matter in Preventing Ethnic Conflict?, 32 N.Y.U. J. INTL L.& POL. 591 (2000) (an
empirical study building from interviews and participant observation regarding the use of soft law in the office of
the high commissioner on national minorities of the Organization for Security and Cooperation in Europe); Shaffer
& Pollack, supra note 8.
61 Stefan Voigt, The Economics of Informal International Law—an Empirical Assessment, in INFORMAL
(Joost Pauwelyn, Ramses Wesssel & Jan Wouters eds., forthcoming 2012), available at The act, however, exempts informal agreements that
relate to specified military activities, have a national security classification, involve coordination between postal
administration and aviation agencies, or related to anti-crime and counternarcotics policies.
He concludes that much more empirical work is needed on the use of informal agreements,
especially by states other than the United States.
Fourth, scholars are increasingly producing large-N databases regarding treaties to assess
the use of different types of provisions in them. Barbara Koremenos used a random sample of
treaties to assess how states deal with uncertainty through treaties, and finds that states respond
to uncertainty through limiting the duration of treaties and including escape clauses under which
the stringency of treaty obligations is relaxed.62 Koremenos also uses this database to assess
when and why states choose to delegate issues, and finds that states are more likely to include
dispute settlement provisions in treaties when they face complex cooperation problems
characterized by uncertainty, incentives to defect, or time inconsistency.63 These findings, she
argues, support a rationalist view that states engage in delegation to resolve these particular types
of challenges.
Fifth and finally, we need empirical work studying the impact of treaties, compared to
other forms of ordering, on state behavior, and assessing whether different domains of
international law vary in line with conditional IL theory. Existing quantitative studies, for
example, have yet to address systematically the impact of treaty design features on state and
other-party behavior (though we do discuss some quantitative and qualitative studies in our
coverage of particular domains of international law).
One empirical issue that has been addressed in relation to treaties is that of selection
effects. George Downs, David Rocke, and Peter Barsoom point out that adducing impact from
becoming a party to treaties is difficult because states have control over the obligations that they
accept; high levels of compliance does not therefore imply that the treaties are having an
independent effect on behavior. 64 To illustrate, consider the debate, prompted by Beth Simmons’
work, over compliance with the international law of money. Her analysis of Article VIII of the
International Monetary Fund treaty showed a high level of compliance.65 Factors enhancing
compliance included, notably, a strong regional effect, suggesting that behavior was driven by
regional dynamics A state’s “rule of law” orientation (as measured by a variable for political risk
analysis) was also important, while general regime features like democracy or dictatorship did
not seem to affect compliance. She contends that reputation concerns and competitive market
forces explain patterns of compliance.
In an important follow-up, Jana Von Stein uses a statistical selection model to estimate
the treaty commitment’s effect on state behavior independent of all sources of selection.66 She
finds that failing to control for the sources of selection leads one to overstate considerably the
effect of an Article VIII commitment on compliant behavior. She concludes that states began
their compliant behavior before signing the treaty because of the extensive requirements to
62 Barbara Koremenos, Contracting Around International Uncertainty, 99 AM. POL. SCI. REV. 549 (2005).
63 See also Barbara Koremenos, When, What, and Why Do States Choose to Delegate?, 71 LAW & CONTEMP.
PROBS. 151 (2008); Barbara Koremenos, If Only Half of International Agreements Have Dispute Resolution
Provisions, Which Half Needs Explaining?, 36 J. LEGAL STUD.189 (2007).
64 George Downs, David M. Rocke & Peter N. Barsoom, Is the Good News About Compliance Good News About
Cooperation?, 50 INTL ORG 379 (1996).
65 Beth A. Simmons, International Law and State Behavior: Commitment and Compliance in International
Monetary Affairs, 94 AM. POL. SCI. REV. 819 (2000); Beth A. Simmons, Money and the Law: Why Comply with the
Public International Law of Money, 25 YALE J. INTL L. 323 (2000).
66 Jana Von Stein, Do Treaties Constrain or Screen? Selection Bias and Treaty Compliance, 99 AM. POL. SCI. REV.
611 (2005).
become a party. She contends that this behavior casts doubt on the argument that an Article VIII
obligation serves as a constraining mechanism that raises the reputational costs that a state will
pay if it reneges. Instead, she sees the treaty as a screening device that signals to markets a
party’s future policy intentions. We believe that Simmons’s contribution withstands the critique
in this particular case, however, because anticipatory effects are nonetheless effects, and the use
of time lags in assessing data can address the point about selection effects.67 That said, the issue
of selection effects, along with endogeneity and reverse causation, is a common, cross-cutting
one with which scholars focusing on compliance need to must grapple.68
International Tribunals
A second cross-cutting issue is the creation of legal institutions. In this section we briefly turn to
empirical work on the operation of international tribunals, which have assumed an increasingly
important role over the last two decades, as international law (to a certain extent) has become
judicialized.69 Judicialization does not necessarily mean, however, that state interests are
ignored, especially if judges exercise bias in their decision making in favor of their own states or
those with similar orientations. Similarly, it also does not mean that tribunals have an
independent effect on behavior. Conditional IL theory is needed to assess both the conditions
under which tribunals are more likely to operate independently, and the conditions under which
they are more likely to shape behavior and structure understandings of international obligations.
Recent years have seen an increased number of international tribunals having distinct
jurisdiction over specific areas, such as trade, human rights, the law of the sea, investment, and
territorial disputes. In contrast to the mid-1980s, when only a handful of standing international
courts were in place, twenty-five such courts have been identified, as of this writing, by the
Project on International Courts and Tribunals.70 This development has spurred empirical
67 See Beth A. Simmons & Daniel J. Hopkins, The Constraining Power of International Treaties: Theory and
Methods, 99 AM. POL. SCI. REV. 623 (2005) (arguing that the effects of Article VIII declarations are robust to a
number of selection models, including matching techniques that try to mimic quasi-experiments). Cf. Joseph Grieco,
Christopher F. Gelpi & T. Camber Warren, When Preferences and Commitments Collide: The Effect of Relative
Partisan Shifts on International Treaty Compliance, 63 INTL ORG. 341 (2009) (providing evidence that state
preferences change based on partisan shifts in the executive branch and that these changes reduce the constraining
effects of Article VIII, although Article VIII continues to exercise significant causal effects even in the face of
relative shifts in executive partisan orientation); Judith Kelley, Who Keeps International Commitments and Why?
The International Criminal Court and Bilateral Non-surrender Agreements, 101 AM. POL. SCI. REV. 573, 573
(2007) (using creative methodology to find that many parties to the Rome Statute of the International Criminal
Court, July 17, 1998, 2187 UNTS 3, refused to enter bilateral nonsurrender agreements with the United States
because of the importance of keeping commitments, concluding that “international commitments do not just screen
states; they also constrain”).
68 Technically, endogeneity refers to a correlation between a measure of an independent variable and the error term
in a regression on the dependent variable. It has many possible causes, one of which is reverse causation: a situation
in which changes in the dependent variable also cause changes in the independent (explanatory) variable. This
occurrence is problematic because the normal assumption is that causality goes from the independent variable to the
dependent variable.
69 We briefly cover empirical work on other international institutions, such as standard-setting bodies, elsewhere.
See Tom Ginsburg & Gregory Shaffer, How Does International Law Work?, in OXFORD HANDBOOK OF EMPIRICAL
LEGAL RESEARCH 753 (Peter Cane & Herbert Kritzer eds., 2011).
70 Included are twelve international courts and arbitral bodies, nine regional bodies, and four hybrid criminal courts
involving a mix of domestic and international judges.
One major topic of debate regards whether these tribunals can be considered
“independent” in some sense. Skeptics argue that international tribunals are simply agents of the
states that create them, and are of minor importance.72 Others argue that international courts
actually do play important roles, if not as central as the doctrinalists might wish.73 In the 1990s,
this question first received extensive attention in relation to the European Court of Justice
The independence of international judges—and thus their role in shaping and applying
international law—is an important empirical question. A small, but increasingly sophisticated,
literature has begun to address it. In some ways, independence is easier to analyze at the
international level than at the national one because judges are typically nominated by state
parties to an international agreement, and one can test if such judges favor their own states. A
relatively straightforward hypothesis of how tribunals produce international law is that judges
will favor their own states when given a chance. Appointing-state participation in a case is
somewhat easier to measure than the comparable independent variable at the national level, in
which studies tend to use proxies for political preferences (for example, in the United States, the
party of the appointing president) to investigate variations in judicial voting.75 If international
judges systematically vote in support of the state party that appointed them, the evidence would
suggest that they are less likely to adopt independent roles based on their own views in
interpreting the law’s meaning over time.
Empirical research has reached different results regarding the independence of judges
from the states that appoint them. Using a multivariate analysis to study the International Court
of Justice, Posner and de Figuierdo find that judges rarely vote against their home states and that
they favor states whose wealth level is close to that of their own states.76 Posner and de Figuierdo
also show connections, although weaker ones, between judges’ voting patterns and the political
or cultural similarities of the states involved in particular disputes. Eric Voeten takes a similar
approach in his comprehensive analysis of voting patterns on the European Court of Human
Rights but, in contrast to the previous study, concludes that judges on this court generally
exercise judicial independence.77 He also finds that career backgrounds make a difference, with
MEN AND WOMEN WHO DECIDE THE WORLDS CASES (2007); Eric Voeten, The Politics of International Judicial
Appointments: Evidence from the European Court of Human Rights, 61 INTL ORG. 669 (2007).
72 See, e.g., Eric Posner & John Yoo, Judicial Independence in International Tribunals, 93 CALIF. L. REV. 1 (2005).
73 Tom Ginsburg & Richard McAdams, Adjudicating in Anarchy: An Expressive Theory of International Dispute
Resolution, 45 WM. & MARY L. REV. 1229 (2004); Laurence Helfer & Anne-Marie Slaughter, Why States Create
International Tribunals: A Response to Professors Posner and Yoo, 93 CALIF. L. REV. 899 (2005). See also the
WTO scholarship assessed in part III below.
74 See discussion in Hafner-Burton et al., supra note 22.
75 We nonetheless note that in international disputes involving private parties (such as investment arbitration), class,
career incentives and ideological orientation could also matter, complicating the analysis, particularly in light of the
relatively small number of decisions.
76 Eric Posner & Miguel de Figueiredo, Is the International Court of Justice Biased?, 34 J. LEGAL STUD. 599
(2005). Although they find no evidence of regional bias, they have little data regarding this last issue because of the
lack of participation of two-thirds of the UN membership.
77 Eric Voeten, The Impartiality of International Judges: Evidence from the European Court of Human Rights, 102
former diplomats being more supportive of national governments,78 and that ad hoc judges who
sit on only a single case show greater support for their national governments.79 From the
perspective of conditional IL theory, these contrasts arguably reflect differences between the
courts being studied. The European Court of Human Rights has jurisdiction only over European
states, and all its judges are also European. Those states are more homogeneous in their interests
and views than either the overall body of UN members or the judges sitting on the ICJ. Also,
since each party to a dispute before the ICJ is permitted to select one judge (as in an arbitral
proceeding),80 there is some expectation that these judges will be loyal to their home state.
Although much work on international tribunals comes out of IR scholarship and, taking a
rationalist orientation, looks at the interests of states, judges, and other actors in conditioning
tribunals’ roles and effects, considerable sociological work on international tribunals has also
been undertaken. This latter work is based on extensive fieldwork and examines the development
of international tribunals over time and the new legal fields in which they play a part. Some of
this work focuses on the role of individual agents in light of broader contests within the legal
profession, using frameworks influenced by Pierre Bourdieu regarding the role of professional
and social capital in constructing law.81 More ethnographic work on international tribunals
would help to round out the picture of judicial motivation in issuing rulings, shaping procedure,
and generating jurisprudential doctrine. It would complement the quantitative research program
on the independence of international judges from their appointing states.
A second central question regarding international tribunals as actors is whether (and the
conditions under which) they affect the production, consolidation, and application of
international law—and thus policy outcomes. Without such an assessment, it is hard to engage in
informed institutional design, either in reforming existing tribunals or establishing future bodies.
Empirical studies, which help us to understand the contexts in which international tribunals are
likely to be effective, form an important part of conditional IL theorizing. Ginsburg and Richard
McAdams, for example, conduct a quantitative analysis of ICJ decision making to illustrate the
“expressive” function of international adjudication.82 They find that the ICJ, frequently lacking
effective sanctioning power, is most effective when, rather than imposing solutions, it facilitates
coordination between the parties by creating a focal point—that is, a reference point which helps
to coordinate expectations where prior agreement is absent. The ICJ is relatively effective in
helping states coordinate their behavior in low stakes conflicts such as border disputes,, but less
effective when armed conflict has already broken out and the states have little incentive to back
down. Similarly, Todd Allee and Paul Huth use a database on territorial disputes to examine the
AM. POL. SCI. REV. 417 (2008).
78 See also Fred J. Bruinsma, The Room at the Top: Separate Opinions in Grand Chambers of the ECHR (1998–
2006), 28 RECHT DER WERKELIJKHEID 7 (2007).
79 Voeten, supra note 77, at 425.
80 Ginsburg & McAdams, supra note 73. For example, Article 31(2) of the ICJ Statute provides: “If the Court
includes upon the Bench a judge of the nationality of one of the parties, any other party may choose a person to sit
as judge. Such person shall be chosen preferably from among those persons who have been nominated as candidates
as provided in Articles 4 and 5.” Article 31 (3) provides: “If the Court includes upon the Bench no judge of the
nationality of the parties, each of these parties may proceed to choose a judge as provided in paragraph 2 of this
81 DEALING IN VIRTUE, supra note 71.
82 Ginsburg & McAdams, supra note 73; see also CONSTANZE SCHULTE, COMPLIANCE WITH DECISIONS OF THE
conditions under which states resort to international legal rulings.83 They focus on domestic
audience costs as a central factor. When leaders think that concessions will generate political
costs, they use international rulings to provide political cover in reaching a settlement. The
judicial decision provides a new focal point that helps leaders resolve conflicting positions, in
part by reducing countervailing domestic political pressures.
In a related vein, a growing body of empirical work illuminates the role of domestic
institutions in affecting the success of international adjudication. In studies of the ECJ, Karen
Alter explains how the Court’s decisions have dynamically mobilized domestic actors, such as
businesses and national judges in lower courts (in contrast to appellate and supreme court
judges).84 This dynamic process helped to consolidate European integration because businesses
brought European Community-based legal claims to domestic courts, whose judges referred legal
questions to the ECJ and issued rulings in light of the ECJ’s responses. More recently, in a study
of the Andean Tribunal of Justice, Lawrence Helfer, Alter, and Florencia Guerzovich assess how
“islands” of effective international adjudication can arise. During its first quarter-century, the
Tribunal issued more than 1400 decisions—over 90 percent of which concern intellectual
property—making it the third most active international tribunal, behind only the ECJ and
European Court of Justice.85 Using a multimethod approach involving fieldwork and quantitative
analysis, they attribute the success of the intellectual property “island” to the relative demand
from particular domestic institutions (in this case, intellectual property agencies), as compared to
others. These two studies demonstrate the value of looking at domestic actors’ incentives to
harness international tribunals’ decisions.86
In sum, the empirical study of tribunals in different disciplines is flourishing in light of
the increasing judicialization of IR. Our focus in this section has been on some broad issues
concerning international tribunals, their judges, and the domestic impact of the tribunals’
decisions. We now turn to additional empirical studies regarding five different domains of
international law.
The growth of empirical work on international law reflects the proliferation and
fragmentation of international law into an array of different substantive domains involving
multiple subject-specific international organizations. While this growth of international
institutional forms has called into question international law’s coherence, it has served diverse
functional purposes, and invites empirical assessment regarding our two organizing questions for
this section: how is each domain of international law produced, and how and under what
conditions does each domain of law matter? A central reason for this domain-specific trend in
83 Todd Allee & Paul Huth, Legitimizing Dispute Settlement: International Legal Rulings as Political Cover, 100
AM. POL. SCI. REV. 219 (2006).
RULE OF LAW IN EUROPE (2001); see also Laurence R. Helfer & Karen J. Alter, Nature or Nurture? Judicial
Lawmaking in the European Court of Justice and the Andean Tribunal of Justice, 64 INTL ORG. 563 (2010)
(comparing ECJ and Andean tribunal).
85 Helfer, Alter & Guerzovich, supra note 34.
(discussing the catalyzing role of private interests in WTO interstate litigation).
empirical work is that the production and impact of international law varies in light of the
different conditions present in particular domains. This basic point was recognized early by
Wolfgang Friedmann in his foundational treatise The Changing Structure of International Law,
where he differentiated between the traditional international law of “co-existence” and the
growth of new international law that addresses particular functional aims in particular domains.87
The fragmentation of international law reflects the varying contexts that states, firms, and
individuals confront in advancing particular goals. Much of the new turn to empirical work has
thus focused on domain-specific questions. Domain-specific analyses have the advantages of
being close to the ground and being capable of isolating features that might operate only in
particular contexts. While generalizing from any specific domain can be risky, the following
series of domain-specific analyses can, in the aggregate, help to provide an overall picture of
how international law works under different conditions, and why it works differently in discrete
Human Rights
International human rights law operates in a distinct context. Unlike the other areas of
law we address below, it does not involve collective-action problems or material externalities
between states. It thus does not pose, from the perspective of strategic game theory,a situations
that can be helpfully analyzed in terms of the prisoner’s dilemma, battle of the sexes, or other
coordination games.88 Rationalist scholars might thus contend that we should see no impact of
international human rights treaties and that international human rights treaties just reflect “cheap
talk.”89 It is consequently of great importance for those advancing human rights norms to
determine whether international human rights law actually does matter and, if so, how and under
what conditions.
Louis Henkin famously observed that almost all states observe almost all their obligations
almost all of the time.90 Downs, Rocke, and Barsoom pointed out that this observation tells us
little about the power of international law because states may be selecting those obligations with
which it is easy to comply.91 This observation is reflected in the large number of reservations
made in human rights treaties, as opposed to other areas of international law such as criminal,
trade, investment, and environmental law, all covered below.92 Moreover, even the Henkin
conjecture about compliance has not been fully verified. Indeed, it does not seem to hold true in
some areas, and human rights law has been a central topic of debate in this regard. Emilia Powell
88 The prisoner’s dilemma game is a “collaborative game,” in which different parties have mutual interests in
collaborating but face incentives not to do so because of fear of noncooperation by the other party. In contrast, the
game of battle of the sexes is a “coordination game” in which each party wishes to cooperate but under their
different terms. For example, a husband and a wife may wish to vacation with each other, but one prefers the
mountains and the other the seaside. See discussion in Arthur A. Stein, Coordination and Collaboration: Regimes in
an Anarchic World, 36 INTL ORG. 299 (1982).
89 See GOLDSMITH & POSNER, supra note 20.
91 Downs, Rocke and Barsoom, supra note 64.
92 See, e.g. Laurence R. Helfer, Exiting Treaties, 91 VA. L. REV. 1579, 1641 (2005) (noting that states have ratified
human rights treaties with “dozens of legally dubious reservations”); Laurence Helfer, Not Fully Committed?
Reservations, Risk and Treaty Design, 31 YALE J. INTL L. 367 (2006).
and Jeffrey Staton, for example, show that nearly 80 percent of the states ratifying the
Convention Against Torture violated the agreement in the year of ratification.93 Powell and
Staton’s piece is part of an especially important debate concerning the efficacy of the human
rights instruments that emerged in the aftermath of World War II. Indeed, most empirical work
on human rights law seeks to directly address the question of whether interventional human
rights law matters. Yet the related issue of why states sign and ratify international human rights
treaties in the first instance has also received some empirical attention.
How human rights law is produced. Most scholars agree that states ratify human rights
treaties primarily for expressive reasons—which differs from the other contexts we discuss
below and helps to make sense of the gap between widespread accession to global human rights
instruments and state practice, with little to no international enforcement of these instruments.
Both rationalist and constructivist scholars have advanced and empirically tested expressive
theories regarding ratification. The world polity school contends that states enter into
international human rights treaties to signal their adherence to global cultural norms, variably
stylized as “universal,” “modern,” and “advanced”; these scholars maintain that treaties
expressively reflect and convey a global acculturation process.94 Rationalists such as Oona
Hathaway and Beth Simmons provide quantitative evidence indicating that, although states
indeed ratify international human rights treaties for expressive reasons, those states having
independent domestic legal enforcement mechanisms are more likely to ratify such treaties if
they believe in the norms and can comply with them at a reasonable cost.95 That is, states with
independent judicial systems are aware that ratification of such a treaty can have consequences
through claims brought before their domestic courts. In parallel, Andrew Moravcsik contends
that, from a liberal internationalist variant of a rationalist perspective, human rights treaties are
ratified by newly established democracies to “lock in” credible domestic human rights policies
through making international law commitments.96 Domestic human rights policies can thus
become more difficult to reverse.
Hathaway launched a wave of new empirical work with her counterintuitive finding that
states that ratify human rights treaties are more likely, on average, to violate the agreements.97
One explanation is an expressive one. She maintains that offending states aim to deflect
93 Convention Against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment, Dec. 10, 1984, S.
TREATY DOC. NO. 20-100 (1988), 1465 UNTS 85; see Emilia Powell & Jeffrey Staton, Domestic Judicial
Institutions and Human Rights Treaty Violation, 53 INTL STUDIES Q. 149 (2009); see also Michael Gilligan &
Nathaniel Nesbitt, Do Norms Reduce Torture?, 38 J. LEGAL STUD. 445 (2009) (using the percentage of states in the
world that are party to the Convention Against Torture as a proxy for the emerging anti-torture norm; using that
proxy to predict torture levels from the date of the Convention’s being opening for signature in 1985, to 2003; and
finding no support for the proposition that the anti-torture norm reduces torture over time).
94 John Boli-Bennett & John W. Meyer, The Ideology of Childhood and the State, 43 AM. SOC. REV. 797 (1978);
GOODMAN & JINKS, supra note 27; BOYLE, supra note 27; Meyer, supra note 27.
95 SIMMONS, supra note 1; Oona A. Hathaway, Do Human Rights Treaties Make a Difference?, 111 YALE L. J.
1935 (2002).
96 Andrew Moravcsik, The Origins of Human Rights Regimes: Democratic Delegation in Postwar Europe, 54 INTL
ORG. 217 (2000) (finding support for his claims through close examination of the creation and evolution of the post–
World War II European human rights regime under the European Convention for the Protection of Human Rights
and Fundamental Freedoms, Nov. 4, 1950, ETS No. 5, 213 UNTS 221).
97 Hathaway, supra note 95; see also Emilie M. Hafner-Burton, Kiyoteru Tsutsui & John Meyer, International
Human Rights Law and the Politics of Legitimation: Repressive States and Human Rights Treaties, 23 INTL SOC.
115 (2008).
international political pressure to reform by signaling an intention to improve human rights
practices through treaty ratification.98 By contrast, states with independent domestic legal
enforcement mechanisms, but with generally good human rights protections, are less likely to
ratify human rights treaties if they are concerned that they might not fulfill all of the obligations
under the treaty.99 In later work, Hathaway provides evidence showing that states’ decisions to
commit to, and comply with, human rights treaties are indeed influenced by the likelihood of
domestic legal enforcement of the treaty’s terms and by the collateral consequences of treaty
commitment.100 Using hazard analysis to test states’ willingness to ratify key human rights
treaties, she finds robust empirical support for these propositions.101
While states alone ratify treaties, nonstate actors are central to the development of human
rights norms, and scholars have documented their key roles. It was nonstate actors, for example,
that were central to the struggle against slavery during the nineteenth century.102 Their work led
not only to the 1926 Convention to Suppress the Slave Trade and Slavery, but also to the broad
acceptance of the view that the prohibition of slavery is a jus cogens norm.103 More recently,
scholars have documented the role of women’s groups in advancing women’s rights, leading to
the 1979 Convention on the Elimination of All Forms of Discrimination Against Women,104 and
the role of children’s rights groups in promoting the 1989 Convention on the Rights of the
Child.105 Understanding the dynamics that allow some groups to succeed using particular
normative frames, whereas others do not, is an important area for further exploration.106
98 A recent analysis by Peter Rosendorff and James Hollyer turns this argument on its head, arguing that offenders
from authoritarian regimes ratify, knowing that they will incur international costs, as a signal to domestic opponents
about the government’s willingness to repress. James Hollyer & B. Peter Rosendorff, Why Do Authoritarian
Regimes Sign the Convention Against Torture? Signaling, Domestic Politics and Non-compliance, Q. J. POL. SCI.
(forthcoming), available at
99 This legalism can be overcome when sufficient concern is placed on international perceptions. See A. W. Brian
Simpson, Britain and the Genocide Convention, 2003 BRIT. Y.B. INTL L. 5 (case study of the reasons behind British
accession to the Convention on the Prevention and Punishment of the Crime of Genocide, Dec. 9, 1948, S. EXEC.
DOC. NO. 91-B (1970), 78 UNTS 277).
100 Oona Hathaway, Why Do Countries Commit to Human Rights Treaties?, 51 J. CONFLICT RESOL. 588 (2007).
101Hazard analysis is a statistical tool that focuses attention on the duration of a phenomenon of interest and the
factors that lead to change. Janet M. Box-Steffensmeier & Bradford S. Jones, EVENT HISTORY MODELING: A GUIDE
102 Steve Charnovitz, Two Centuries of Participation: NGOs and International Governance, 18 MICH. J. INTL L.
183, 191–92 (1997) (describing efforts of nongovernmental organizations (NGOs) to abolish slavery); Joseph S.
Nye Jr., The Information Revolution and the Paradox of American Power, 97 ASIL PROC. 67, 70 (2003)
(“Transnational religious organizations opposed to slavery date back to 1775.”).
103 Sept. 25, 1926, 46 Stat. 2183, 60 LNTS 253; see RESTATEMENT (THIRD) OF THE FOREIGN RELATIONS LAW OF
THE UNITED STATES §702 (1987) (listing prohibition on slavery as jus cogens).
BYRNES, THE FIRST CEDAW IMPACT STUDY: FINAL REPORT 25 (2000) (finding that CEDAW would not have been
adopted without the work of NGOs); see also MARGARET E. KECK & KATHRYN SIKKINK, ACTIVISTS BEYOND
BORDERS: ADVOCACY NETWORKS IN INTERNATIONAL POLITICS 166–84 (1998) (describing how networks of NGOs
took up the issue of violence against women).
105 Nov. 20, 1989, 1577 UNTS 3; see Cynthia Price Cohen, The Role of Nongovernmental Organizations in the
Drafting of the Convention on the Rights of the Child, 12 HUM. RTS. Q. 137 (1990) (describing involvement of
NGOs as shown in UN and NGO documents); see also Jean Grugel & Enrique Peruzzotti, Grounding Global Norms
in Domestic Politics: Advocacy Coalitions and the Convention on the Rights of the Child in Argentina, 42 J. LATIN
AM. STUD. 29 (2010) (describing activists’ role in promoting children’s rights in Argentina); Jean Grugel & Enrique
Peruzzotti, Claiming Rights Under Global Governance: Children’s Rights in Argentina, 13 GLOBAL GOVERNANCE
How and under what conditions international human rights law matters. Most empirical
scholarship continues to revolve around the fundamental question of whether and under what
conditions international human rights treaties make a difference for those ratifying them.
Scholars have highlighted the conditions that affect compliance with international human rights
norms. Understanding these links has normative implications for those seeking to advance the
human rights project.
One emerging theme in this literature is that effective human rights protection requires
domestic institutions, so that accession is more likely to improve performance in democracies
than in autocracies. The engagement of civil society, in particular, appears critical. Linda Keith
uses a relatively simple model to show that judicial independence is positively correlated with
human rights protection around the world.107 Eric Neumayer uses a more sophisticated modeling
approach to show that ratification of human rights instruments improves protections within states
with democratic institutions and a strong civil society.108
Because the nature of the state and of the institutions within it affect whether
international law matters, one potential problem with empirical studies is the use of overinclusive
samples. In a subtle, book-length treatment, Simmons takes the important methodological step of
disaggregating the sample of states so as to exclude both false positives (states that ratify treaties
without intending to comply) and false negatives (states that need not ratify treaties to credibly
enforce human rights guarantees).109 She notes, “in civil and political rights, a treaty’s greatest
impact is likely to be found not in the stable extremes of democracy and autocracy, but in the
mass of nations with institutions in flux, where citizens potentially have both the motive and the
means to succeed in demanding their rights.”110 She finds that, for this middle group of states
(after excluding the outliers), ratification of human rights instruments is associated with positive
improvements in rights protection, with key intervening variables being domestic mobilization
and domestic judicial enforcement.
For the middle group of states, she finds that human rights treaties shape executive
agendas, provide support for litigation of human rights issues before domestic courts, and spark
domestic popular mobilization. She summarizes her own extensive quantitative work, coupled
with some qualitative studies, as follows: “Human rights outcomes are highly contingent on the
199 (2007) (describing a case study of the impact of the Convention on the Rights of the Child on domestic
advocacy in Argentina).
HUMAN RIGHTS, 1944–1955 (2003) (the National Association for the Advancement of Colored People was unable to
advance a human rights agenda before the United Nations—which resulted in the launching of the Civil Rights
Movement without the social and economic rights focus that it needed to achieve black equality); KECK & SIKKINK,
supra note 104, at 184 (noting how incorporation of women’s issues into a “ ‘rights’ frame, or master frame
supplement[ed] the ‘discrimination’ frame of the 1979 women’s convention and the ‘development’ frame in the
women in development debate”).
107 Linda Camp Keith, Judicial Independence and Human Rights Protection Around the World, 85 JUDICATURE 195
108 Eric Neumayer, Do International Human Rights Treaties Improve Respect for Human Rights? 49 J. CONFLICT
RESOL. 925 (2005); cf. SIMMONS, supra note 1; Hathaway, supra note 95; Christof Heyns & Frans Viljoen, The
Impact of the United Nations Human Rights Treaties on the Domestic Level, 23 HUM. RTS. Q. 483 (2001); Linda C.
Keith, The United Nations International Covenant on Civil and Political Rights: Does It Make a Difference in
Human Rights Behavior?, 36 J. PEACE RES. 95 (1999).
109 SIMMONS, supra note 1.
110 Id. at 155.
nature of domestic demands, institutions and capacities.”111 International human rights treaties,
in other words, provide leverage for domestic mobilization to improve outcomes, but do not, on
their own, work well in the absence of domestic mobilization. This finding is consistent with
other empirical studies that stress the role of civil society mobilization in domestic settings if
international human rights law is to be implemented effectively.112 Indeed, the existence of civil
society organizations is a central variable for sociologists working in the world polity tradition;
studies find that diffusion processes work, though subject to particular local conditions in which
“modern” norms are more likely to take hold.113
The emphasis on the mediating power of domestic institutions and civil society groups
illustrates that the effects of human rights treaties can be indirect and take multiple channels. In
an important ethnographic study, Sally Merry investigated the links between the global
production and local appropriation of human rights law affecting gender violence in five states in
the Asia-Pacific region, focusing on the roles of UN conferences, transnational NGO activism,
and other transnational exchanges of ideas and practices.114 She highlights “the role of activists
who serve as intermediaries between different sets of cultural understandings of gender,
violence, and justice”115 and who appropriate international legal norms for local ends. Merry’s
work finds that international human rights law is more likely to matter where nonstate actors
operate effectively as intermediaries to convey and adapt human rights norms to address
particular domestic contexts. These processes of local adaptation constitute forms of
indigenization and bricolage, or what might be called “localized globalisms.”116
In a world of international legal fragmentation, areas of international law can
complement or counter each other’s influences within states.117 International economic law and
policy, for example, can potentially impede or foster human rights improvements.118 Actors may
sometimes use different regimes of international law to compete for influence. Scholars have
empirically examined these processes and evaluated the outcomes. Boyle and Minzee Kim, for
example, use quantitative methods to assess the relative impact across over seventy low-income
and middle-income developing countries of conflicting human rights and neoliberal development
norms adopted over a twenty-year period in human rights treaties and structural adjustment
111 Id. at 373.
112 See, e.g., Katerina Linos, Diffusion Through Democracy, 55 AM. J. POL. SCI. 678 (2011) (examines why soft
international and transnational legal norms often trigger major national legal reforms, despite the strong constraints
that domestic constituencies impose on leaders of democratic states); Emilie M. Hafner-Burton & Kiyoteru Tsutsui,
Human Rights in a Globalizing World: The Paradox of Empty Promises, 110 AM. J. SOC. 1373 (2005).
113 See, e.g., BOYLE, supra note 27 (using a combination of quantitative and qualitative methods to investigate how
actors at the international, national, and local levels affect policies and practices on female circumcision).
114 MERRY, supra note 28.
115 Sally Engel Merry, Human Rights and Transnational Culture: Regulating Gender Violence Through Global Law,
44 Osgoode Hall Law Journal 53, 55 (2006).
(regarding the adoption of global human rights and neoliberal economic prescriptions in Latin America).
117 Shaffer & Pollack, supra note 58.
(finding that entry into structural adjustment agreements with the World Bank has a negative impact on human
rights protections); Emilie M. Hafner-Burton, Trading Human Rights: How Preferential Trade Agreements
Influence Government Repression, 59 INTL ORG. 593 (2005) (showing that international linkages in the form of
preferential trade agreements can improve human rights practices).
agreements, respectively.119 Their study finds that the human rights norm of universal primary
education won out, in significant part, through the operation of transnational NGOs that
harnessed the legitimacy of these norms.
The questions of whether, when, and how human rights agreements and norms make a
difference will remain important, with much still to be studied. But the work to date has
significantly advanced conditional IL theory. We see four major challenges for this literature.
First, the field needs to follow Simmons’s approach of disaggregating large-N analysis,
discarding outliers that either ratify international human rights agreements with no intention of
enforcing them (Zimbabwe), or comply with international human rights provisions without any
need for ratifying them (United States). The actual impact of the instruments is likely to be seen
at the margins—for states in the middle. Second, the field needs better measures for human
rights outcomes, which is the dependent variable in quantitative research. Much of the existing
quantitative work relies on subjective indicators of human rights violations. The U.S.
Department of State annual reports, for example, are attractive because of their breadth and their
longitudinal coverage, but are subject to some political biases. A small, but important, literature
on the challenges of measuring human rights has coalesced and is likely to produce incremental
improvements in the indicators used in evaluating human rights performance.120 Producing new
indicators is difficult, but all the standard indicators of human rights abuses have their flaws.
Third, many empirical studies use ratification as a binary variable to capture participation in
international human rights regimes. But surely participation is not an all or nothing matter; state
participation comes in different degrees and modalities. Thinking carefully about the
independent variable will be important for future work trying to capture the impact of
international regimes. Finally, a combination of quantitative methods and case studies involving
sustained fieldwork would be helpful in further assessing the mechanisms through which, and the
conditions under which, international human rights law matters. The scholarship we have
discussed represents a step in the right direction.121
International Criminal and Humanitarian Law
The problem faced in international criminal law (ICL) and international humanitarian law
(IHL) is more complex than that of human rights law. On the one hand, ICL and IHL , have, in
119 Minzee Kim, Elizabeth Boyle & Kristin Haltinner, Neoliberalism, Transnational Education Norms, and
Education Spending in the Developing World, 1983–2004, LAW & SOC. INQUIRY (forthcoming 2012).
120 David L. Cingarelli & David L. Richards, The Quantitative Study of Human Rights Violations, in THE
ENCYCLOPEDIA OF HUMAN RIGHTS (David P. Forsyth ed., 2009), at
tative_Study_of_Human_Rights_Violations.pdf; TODD LANDMAN & EDZIA CARVALHO, MEASURING HUMAN
RIGHTS (2010); see also Kevin E. Davis, Benedict Kingsbury & Sally Engle Merry, Indicators as a Technology of
Global Governance (Institute for International Law and Justice Working Paper No. 2010/2, 2011) (discussion of
how indicators have been used in global governance and how the use of indicators has the potential to alter the
nature of global governance). For an earlier work, see HUMAN RIGHTS AND STATISTICS: GETTING THE RECORD
STRAIGHT (Thomas B. Jabine & Richard P. Claude eds., 1992).
121 Ryan Goodman, Derek Jinks & Andrew K. Woods, Social Science and Human Rights, in UNDERSTANDING
SOCIAL ACTION, PROMOTING HUMAN RIGHTS (Ryan Goodman, Derek Jinks & Andrew Woods eds., forthcoming
part, the same overarching goal as human rights law in expressing norms of proper conduct.122
On the other, ICL and IHL often involve issues of reciprocity regarding adversaries’ treatment of
each other’s troops—leading to a prisoner’s dilemma situation. For instrumentally oriented
theorists, states and their armed forces, in an effort to ensure that their own combat forces and
civilians are treated humanely, use international law to codify reciprocal understandings.123 Also
unlike human rights law, some crimes in ICL, such as piracy on the high seas, involve collective-
action problems. ICL and IHL differ as well from the areas of law we cover in subsequent
subsections—international trade, investment, and environmental law—in that ICL and IHL often
involve matters affecting state survival or elite struggles for power. In such matters of “high
politics,” law can play a more subordinate role. As a result, normative dilemmas over the
appropriate use of international law compared to other political alternatives become particularly
salient, highlighting the need for conditional IL theory.
The explosive growth of international institutions to regulate the conduct of armed
conflict—including the expansion of ICL—has been one of the major developments of the past
two decades. Nearly fifty years after Nuremberg, the international community created two major
ad hoc international tribunals, the International Criminal Tribunal for Rwanda and the
International Criminal Tribunal for the Former Yugoslavia (ICTY), followed by the standing
International Criminal Court, as well as ad hoc tribunals for the Lockerbie bombing, the
assassination of former Lebanese prime minister Rafik al Hariri, and war crimes committed in
Sierra Leone. These developments have spurred policy disputes with major normative
implications, giving rise to empirical scholarship in support of contending claims. A central
claim of the anti-impunity movement, from Nuremberg onward, has been that criminal
prosecutions for grave violations of human rights will have a significant deterrent effect, will
facilitate democratic transitions, and will help shape collective memories in ways more
conducive to enduring peace.124 This claim, however, needs to be empirically examined, in light
of different conditions that may affect desired outcomes.
How ICL and IHL are produced. Most of the empirical work regarding why IHL and ICL
are produced builds from historical, qualitative case studies.125 In the 1990s, France, the United
Kingdom, and the United States, working through the UN Security Council, pushed together for
the creation of ad hoc international tribunals. The United States, however, resisted the creation of
122 See, e.g., Gabriella Blum, The Laws of War and the “Lesser Evil,” 35 YALE J. INTL L. 1, 51 (2010) (describing
IHL’s “expressive force” as its “single source of strength”); Robert D. Sloane, Prologue to a Voluntarist War
Convention, 106 MICH. L. REV. 443, 460 (2007) (“Efforts to revise IHL must consider not only the probable effect
of proposed new rules on incentive structures but also their expressive dimensions.”); Robert D. Sloane, The
Expressive Capacity of International Punishment: The Limits of the National Law Analogy and the Potential of
International Criminal Law, 43 STAN. J. INTL L. 39, 44 (2007) (“[i]nternational criminal tribunals can contribute
most effectively to world public order as self-consciously expressive penal institutions”).
123 See, e.g., James D. Morrow, When Do States Follow the Laws of War?, 101 AM. POL. SCI. REV. 559, 566 (2007).
124 Payam Akhavan, Beyond Impunity: Can International Criminal Justice Prevent Future Atrocities?, 95 AJIL 7, 9
(2001) (“The empirical evidence suggests that the ICTY and the ICTR have significantly contributed to peace
building in postwar societies, as well as to introducing criminal accountability into the culture of international
relations.”); M. Cherif Bassiouni, Combating Impunity for International Crimes, 71 U. COLO. L. REV. 409, 410
(2000) (“The pursuit of justice and accountability, it is believed, fulfills fundamental human values, helps achieve
peace and reconciliation, and contributes to the prevention and deterrence of future conflicts.”).
125 See, e.g., Michel Veuthey, From Solferino to Kosovo: The Contribution of International Humanitarian Law to
International Security, in INTERNATIONAL HUMANITARIAN LAW: ORIGINS 212–13 (John Carey, William V. Dunlap
& R. John Pritchard eds., 2003) (describing events that led to particular changes in international humanitarian law).
the International Criminal Court, which was supported by European states and many others,
including Canada.
Empirical studies have examined the various alliances between states, NGOs, and
international organizations that worked to create these new tribunals.126 This empirical work has
been central in challenging state-centric theories of international behavior, and illustrates the
significant theoretical payoffs for the qualitative empirical work we describe. ICL and IHL have
been produced through the work of individuals, NGOs, and states, with private actors and
particular events often being the catalysts.127 The role of Henry Dunant, a Swiss businessman, in
founding the International Committee of the Red Cross in 1863 and lobbying states to create the
1864 (Geneva) Convention for the Amelioration of the Condition of the Wounded in Armies in
the Field is well documented.128 The Red Cross has continued to be an active drafter and
proponent of the subsequent Geneva and Hague Conventions and their protocols.129 Dunant
acted as a precursor to later prominent figures in IHL, such as Rafael Lemkin regarding the
crime of genocide. NGOs also acted as catalysts for the Ottawa Convention, pursuant to the 1997
International Campaign to Ban Landmines, for which the campaign (with its leader Jody
Williams) won the 1997 Nobel Peace Prize.130
Scholars have paid particular attention to the inner workings of international criminal
tribunals and the factors leading to the elaboration of this field of law over the last decades.
Given its status as the most mature and productive of the international criminal tribunals, much
attention has focused on the ICTY. The sociologist John Hagan examined the underlying
conditions pursuant to which the charismatic chief prosecutor Louise Arbour, supported by a
22–47 (2005) (describing involvement of NGOs and other actors in campaign for the International Criminal Court);
(2001) (describing process leading up to establishment of ICTY).
127 See, e.g., Bohunka O. Goldstein, Implementation of International Humanitarian Law by Diplomacy, Official and
Non-governmental, in INTERNATIONAL HUMANITARIAN LAW, supra note 125, at 161, 176–77 (describing
International Campaign to Ban Landmines (launched by sixteen NGOs) and NGO Coalition for an International
Criminal Court); Theodor Meron, The Humanization of Humanitarian Law, 94 AJIL 239, 243 (2000) (describing
events leading to changes in IHL); Veuthey, supra note 118.
128 Aug. 22, 1864, reprinted in THE LAWS OF ARMED CONFLICTS 279 (Dietrich Schindler & Jiri Toman eds., 3d rev.
ed. 1988); see, e.g., Christopher J. Greenwood, Historical Development and Legal Basis, in THE HANDBOOK OF
INTERNATIONAL HUMANITARIAN LAW 15, 22 (Dieter Fleck ed., 2d ed. 2008) (briefly describing Dunant’s
RED CROSS (1999).
129 François Bugnion, The International Committee of the Red Cross and the Development of International
Humanitarian Law, 5 CHI. J. INTL L. 191, 191 (2004) (“Notwithstanding its private-initiative origins, the
International Committee of the Red Cross . . . has been the main driving force behind the development of
international humanitarian law for 140 years.”); Finnemore, supra note 27 (exploring the role of the ICRC in
establishing and codifying the principles in the Geneva Conventions); Ratner, supra note 39.
130 Convention on the Prohibition of the Use, Stockpiling, Production and Transfer of Anti-personnel Mines and on
Their Destruction, Sept. 18, 1997, 19 ILM 1530 (1997). Richard Price shows how international civil society, in the
form of the global coalition against the use of land mines, successfully reframed the issue of land mines from a
military to a humanitarian issue and thereby changed the norms and behavior of the vast majority of the world’s
states, which signed an international convention to ban the use of antipersonnel mines in 1997. Richard Price,
Reversing the Gun Sights: Transnational Civil Society Targets Land Mines, 52 INTL ORG. 613 (1998). The treaty,
which entered into force on March 1, 1999, has 157 parties as of November 29, 2011. See
specific institutional context, strategically chose key cases and worked the media to establish the
ICTY’s legitimacy of the ICTY and help build the field of ICL.131 This work highlights the
contingent and transformative role that individuals can play on the international plane. Hagan,
Ron Levi, and Gabrielle Ferrales subsequently conducted further field interviews, participant
observation, and a two-wave survey of ICTY employees to assess changes in the Tribunal in
light of shifts in U.S. policy toward it under the Bush administration, as mediated by internal
organizational dynamics.132 They found a decline in work satisfaction and a drop in morale
resulting from a loss of a sense of organizational relevance which impede the Tribunal’s work.
This study should prompt theorists to examine more carefully how organizational behavior can
be affected by relations between the organization in question and external constituencies (the
United States in this case). A similar literature is emerging on the International Criminal Court,
although the results must be considered preliminary in view of the small number of cases that the
Court has handled to date.133
Relatively few studies have examined national court prosecutions of international
crimes—which can serve as a substitute for international institutional enforcement. In one
comprehensive study, however, Maximo Langer shows that national prosecutions based on
universal jurisdiction are relatively rare and subject to political checks, and that they
consequently focus on defendants from states that are less likely to generate significant political
costs for the prosecuting state.134 Similarly, Eugene Kontorovich and Steven Art study the
incidence of universal jurisdiction in prosecutions for piracies committed over a twelve-year
period (1998–2009) and find that extra-national prosecution occurs in only 1.47 percent of the
cases, reflecting severe collective-action problems.135 These findings suggest why states might
turn to international machinery to overcome such difficulties. They also illustrate both the power
of empirical work to inform normative debates and the risks in simply assuming that domestic
systems provide an effective substitute for international law.
How and under what conditions ICL and IHL matter. The empirical evidence suggests
that the impact of ICL enforcement should be broken down in terms of long-term and short-term
effects under different conditions. Regarding long-term effects, the evidence indicates that
Nuremberg had an important educative effect on reconstituting German national identity.136
International criminal tribunals, in other words, can potentially serve a long-term educative
purpose, affecting national reconciliation efforts and, over time, collective memories of the past,
132 John Hagan, Ron Levi & Gabrielle Ferrales, Swaying the Hand of Justice: The Internal and External Dynamics
of Regime Change at the International Criminal Tribunal for the Former Yugoslavia, 31 LAW & SOC. INQUIRY 585
133 Cf. Nicole Deitelhoff, The Discrusive Process of Legalization: Charting Islands of Persuasion in the ICC Case,
63 INTL ORG. 33 (2009) (using discourse analysis to show a change in framing at a critical turning point in the
negotiations when majorities shifted away from the great powers’ positions, suggesting the role of persuasion);
Philippe Kirsch & John T. Holmes, The Rome Conference on an International Court: The Negotiating Process, 93
AJIL 2 (1999); Beth A. Simmons & Allison Danner, Credible Commitments and the International Criminal Court,
64 INTL. ORG. 225 (2010) (applying a rationalist approach).
134 Langer, supra note 34.
135 Kontorovich & Art, supra note 34.
136 Susanne Karstedt, Coming to Terms with the Past in Germany After 1945 and 1989: Public Judgments on
Procedures and Justice, 20 LAW & POLY 15 (1998).
thereby having an impact on future interstate relations. Scholars have also empirically shown that
the development of domestic criminal law and legal institutions has significantly reduced
violence within states over time. It remains to be seen, however, whether the recent rise of ICL
and ICL institutions—under very different conditions of legitimacy from those of domestic
courts—will have long-term deterrent effects, especially in situations involving civil conflict.137
A group of realist scholars have used case studies to suggest that prosecuting war crimes
may have perverse consequences, possibly spurring leaders and insurgents to resist negotiations
to cease combat because of fear of prosecution.138 They contend that such criminal prosecutions
could lead to exacerbated human rights violations. While much empirical work in the arena of
ICL and transitional justice is case specific, making generalization difficult, some scholars have
engaged in broader, cross-national studies. Jack Snyder and Leslie Vinjamuri, two scholars in the
field of international security, survey the claims of proponents of international prosecution and,
in a study of thirty-two cases of civil war, find that prosecution according to universal standards
is often not helpful in reducing violations.139 They also find that credible amnesties are generally
associated with better outcomes. Similarly, Julian Ku and Jide Nzelibe review data gathered on
the fates of African coup participants for the period 1955–2003 and find that coup leaders in
Africa are unlikely to be deterred by the threat of prosecution before an international criminal
tribunal and that such prosecution could rather exacerbate atrocities by reducing the incentives of
perpetrators to engage in peace negotiations.140
Numerous other studies, however—both case specific and general—suggest that using
criminal trials for human rights abuses has had positive effects, which vary depending on their
timing and use. Worth noting in this context is that ICL is often linked, directly or indirectly,
with the use of transitional justice mechanisms within states, such as criminal trials, truth
commissions, and the barring of individuals from future public employment. The literature on
ICL consequently overlaps with the broader literature on transitional justice following civil
conflicts. The best work in this area adopts a careful, nuanced approach, instead of making stark
either/or judgments. Sikkink and Carrie Walling stress the importance of examining the
conditions under which criminal trials can contribute to improving human rights.141 Based on a
137 See, for example, studies of more recent intrastate conflicts, such as MY NEIGHBOR, MY ENEMY: JUSTICE AND
COMMUNITY IN THE AFTERMATH OF MASS ATROCITY (Eric Stover & Harvey M. Weinstein eds., 2004) (finding that
“international or local trials may have little relevance to reconciliation in post-war countries,” so that “coordinated
multi-systemic strategies must be implemented if social repair is to occur”); Laurel Fletcher & Harvey Weinstein,
Violence and Social Repair: Rethinking the Contribution of Justice to Reconciliation, 24 HUM RTS. Q. 573 (2002)
(building from an interview-based study of Bosnians and arguing that for any society to reconstitute in a peaceful
fashion, alternative interventions have to be implemented together with war crimes trials); James Meernik, Justice
and Peace? How the International Criminal Tribunal Affects Societal Peace in Bosnia, 42 J. PEACE RES. 271 (2005)
(finding that the ICTY had only a limited effect on improving relations among Bosnia’s ethnic groups); and David
Mendeloff, Trauma and Vengeance: Assessing the Psychological and Emotional Effects of Post-conflict Justice, 31
HUM. RTS. Q. 592 (2009) (surveying the scant empirical evidence on transnational justice and finding little support
for the proposition that truth-telling harms individuals or that it satisfies victims’ need for justice).
138 Jack Goldsmith & Stephen D. Krasner, The Limits of Idealism, 132 DAEDALUS 47 (2003).
139 Jack Snyder & Leslie Vinjamuri, Trials and Errors: Principle and Pragmatism in Strategies of International
Justice, 28 INTL SECURITY 5 (2003–04).
140 Julian Ku & Jide Nzelibe, Do International Criminal Tribunals Deter or Exacerbate Humanitarian Atrocities?,
84 WASH. U. L. REV. 777 (2006).
141 Kathryn Sikkink & Carrie B. Walling, The Impact of Human Rights Trials in Latin America, 44 J. PEACE RES.
427 (2007); see also Hunjoon Kim & Kathryn Sikkink, Explaining the Deterrence Effect of Human Rights
survey of truth commissions and human rights trials in 192 states, the two researchers find that
amnesties and trials for human rights violations are typically used in combination over time; for
example, if earlier amnesties erode, they are sometimes replaced by trials. It is consequently
wrong to analyze amnesties and trials as if they were mutually exclusive.
The impact of ICL may depend, in part, on perceptions of its legitimacy. Some relevant
empirical literature has addressed whether the outcomes of the ICTY’s criminal trials have been
biased. James Meernik and Kimi King found no evidence the Tribunal was treating Serbs more
harshly than other defendants, partially allaying concerns of “victor’s justice.”142 Meernik
likewise found that the presence on a panel of more judges from NATO states is associated with
higher rates of acquittal, and no higher levels of sentencing.143 From a constructivist perspective,
such apparent exercises of impartiality could help to legitimize an international court,
empowering it as an actor in constructing the emerging field of ICL. Yet in research relevant to
the claims of backlash against the ICTY and its appointed task, Hagan and Sanja Ivonic
conducted surveys among people of various ethnicities in the former Yugoslavia, and they found
compelling evidence of the localized influence of views toward the trial of war criminals. They
found, for example, that “Serbs in Belgrade are distinctive in insisting that war criminals be tried
in their places of origin, while Serbs in Sarajevo and Vukovar agree with other groups in these
settings that war criminals should be tried in locations where their crimes occurred,”144
Finally, it is crucial to identify the channels through which IHL affects the conduct of
war. One obvious channel is its internalization by militaries. In examining how American
military lawyers internalize the values of international human rights and humanitarian law, Laura
Dickinson engaged in extensive interviewing of military lawyers and noted the importance of
organizational culture and structure.145 Parallel studies of other militaries would inform practical
efforts to advance compliance.
Prosecutions for Transitional Countries, 54 INTL STUD. Q. 939 (2010) (examining one hundred transitional states
during the period 1980–2004, and finding that “countries with human rights trials after transition have better human
rights practices than countries without trials”).
142 James Meernik & Kimi King, The Sentencing Determinants of the International Criminal Tribunal for the
Former Yugoslavia: An Empirical and Doctrinal Analysis, 16 LEIDEN J. INTL L. 717 (2003).
143 James Meernik, Victor’s Justice or the Law: Judging and Punishing at the International Criminal Tribunal for
the Former Yugoslavia, 47 J. CONFLICT RESOL. 140 (2003).
144 John Hagan & S. K. Ivkovic, War Crimes, Democracy, and the Rule of Law in Belgrade, the Former Yugoslavia,
and Beyond, 605 ANNALS AM. ACAD. POL. & SOC. SCI.130 (2006).
145 Laura A. Dickinson, Military Lawyers on the Battlefield: An Empirical Account of International Law
Compliance, 104 AJIL 1 (2010); Laura A. Dickinson, Military Lawyers, Private Contractors, and the Problem of
International Law Compliance, 42 NYU J. INTL L. & POL. 355 (2010). In both cases, she builds from a series of
interviews of U.S. military lawyers in the Judge Advocate General Corps operating in Iraq. See also LAURA A.
DICKINSON, OUTSOURCING WAR AND PEACE (2010). For quantitative studies on the impact of the law of war, see
that self-imposed limitations of international law and custom are often crucial to determining how and when force is
used in international relations); James D. Morrow, When Do States Follow the Laws of War?, 101 AM. POL. SCI.
REV. 559 (2007) (finding that ratification of treaties does not affect the behavior of nondemocracies, but does for
democracies); Benjamin Valentino, Paul Huth & Sarah Croco, Covenants Without the Sword: International Law and
the Protection of Civilians in Times of War, 58 WORLD POL. 339 (2006) (finding no evidence that signatories of the
Hague or Geneva Conventions of 1907 and 1949 killed fewer civilians than did nonratifiers, or that democratic
ratifiers killed fewer than others).
Overall, given the conflicting claims regarding the impact of ICL and IHL, further
empirical work will be required to assess the conditions under which they are more likely to have
positive effects. From our assessment of the empirical evidence, it appears that the impact varies
as a function of different conditions, such as the level and nature of the civil conflict, the timing
of the trial in relation to the conflict, and whether a state is on the road to democratization.146
Scholars also need to assess empirically the impact of factors such as the location of trials and
the identity of those conducting them.
International Trade Law
International trade law, unlike international human rights law, is based on the mechanism
of reciprocity; one state provides trade concessions to others in return for concessions of
reciprocal value.147 In addition, it involves prisoner’s dilemma situations since each of the parties
to an agreement has an incentive to defect while the others comply, potentially making all of
them worse off if none comply. The predominant theory among economists is that states agree to
international trade law in order to resolve the prisoner’s dilemma,148 in particular through
providing for monitoring and enforcement mechanisms. International trade law, moreover,
unlike ICL and IHL, typically involves issues of lower politics than state security, civil conflict,
and the use of force, which enhances the prospects for compliance if effective institutions can be
Nonetheless, power does matter in the production of international trade law, both in
setting the terms of cooperation and in enforcing these terms; states with larger markets can
threaten to withdraw access to their markets if other states do not agree to the rules that they
prefer or if they do not comply with these rules.149 Richard Steinberg has empirically addressed
this point in relation to trade and environment issues, showing how states exercising market
power have advanced their positions in different forums.150 Other scholars, in a parallel but
different vein, contend that international trade law helps to lock in the advantages of
transnational capital, as well as of powerful states, pointing to the Agreement on Trade-Related
146 See also Oskar Thoms, James Ron & Roland Paris, Does Transitional Justice Work? Perspectives from Empirical
Social Science [the article is no longer available on SSRN, so can’t realistically be cited as an SSRN working
paper.] (unpublished manuscript, 2008) (providing a useful overview of the empirical debates) (on file with authors).
Broda, Nuno Limao & David Weinstein, Optimal Tariffs and Market Power: The Evidence, 98 AM. ECON. REV.
2032 (2008) (using new empirical data and techniques to provide evidence supportive of the terms-of-trade theory).
Giovanni Maggi and Andrés Rodríguez-Clare provide a complementary theory within economics, according to
which governments are motivated to sign trade agreements by the desire to make credible commitments in relation
to domestic industrial lobbies. Giovanni Maggi & Andrés Rodríguez-Clare, A Political-Economy Theory of Trade
Agreements, 97 AM. ECON. REV. 1374 (2007) (predicting “that trade liberalization is deeper when capital is more
mobile across sectors, and when governments are more politically motivated”); see also Edward Mansfield & Eric
Reinhardt, International Institutions and the Volatility of International Trade, 62 INTL ORG. 621 (2008) (finding
that joining international trade institutions reduces trade volatility and thus increases predictability and economic
stability for both states and economic actors).
149 Steinberg, supra note 9.
150 Id.
Aspects of Intellectual Property Rights as a prime example.151 In other words, one can see a
structural tilt in the ability of larger states and interests within them to shape and deploy World
Trade Organization (WTO) rules to advance their interests, directly and diffusely, through using
material, ideological, and institutional resources.152
International trade law has been extensively studied empirically, which likely reflects the
relative success of the WTO’s dispute settlement system, the availability of high-quality data,
and the long-running interest of economists in international trade matters.153 Much of this
empirical work is read and assessed within the trade policy community, thereby affecting
litigation strategies and reform proposals. In this brief assessment, we first examine empirical
work on the WTO, focusing on the use of the organization’s dispute settlement system and on
the judicial findings of the Appellate Body and panels.154 We then examine the impact of, these
legal mechanisms.
How international trade law is produced. A sizable body of empirical work now exists
on whether use of the WTO dispute settlement system reflects bias in favor of large, wealthy
states. Three hypotheses have been formulated and empirically tested: namely, that the system is
not biased since use simply reflects economic size; that market power favors use by large,
wealthy states because of their ability to retaliate to enforce rulings; and that differences in legal
capacity explain disparate use. These studies have normative and policy implications as regards
both the fairness of the WTO dispute settlement system and strategies that states might develop
to harness it more effectively.
Henrik Horn, Petros Mavroidis, and Häkan Nordstom spurred this field of analysis with
their article “Is the Use of the WTO Dispute Settlement System Biased?”155 They predict how
many claims a member would bring based on its trading profile and then check this prediction
against the actual number of claims brought. They find that states’ initiation of WTO complaints
roughly tracks their share of global trade, although they note some outliers—in particular, Japan.
Almost ten years later, Joseph Francois, Horn, and Niklas Kaunitz likewise compare actual WTO
complaints initiated by states against their model’s predicted number of complaints, which is
based on each member’s size and industrial structure.156 They use new statistical data of disputes
from a World Bank database and incorporate an assessment of import-restricting measures at the
industry level. They again find a strong positive correlation between the number of a member’s
151 Cf. BRAITHWAITE & DRAHOS, supra note 147, at 79–80; B. S. Chimni, The World Trade Organization,
Democracy and Development: A View From the South, 40 J. WORLD TRADE 5, 5 (2006) (“[T]he creation of WTO,
its rules and organization, is the work of powerful social forces and states. It has emerged as a key institution to
sustain the global capitalist order to the advantage of an emerging transnational capitalist class (TCC) whose
interests are articulated by powerful states.”).
152 Gregory Shaffer, Power, Governance, and the WTO: A Comparative Institutional Approach, in POWER IN
GLOBAL GOVERNANCE 130 (Michael Barnett & Raymond Duvall eds., 2005).
153 Henrik Horn and Petros Mavroidis provide an assessment of much of the quantitative work from law and
economics to date. Henrik Horn & Petros Mavroidis, A Survey of the Literature on the WTO Dispute Settlement
System (Centre for Economic Policy Research, Discussion Paper No. 6020, 2007).
154 We address elsewhere studies on the negotiation of WTO rules. See Ginsburg & Shaffer, supra note 69.
155 Henrik Horn, Petros Mavroidis & Häkan Nordstrom, Is the Use of the WTO Dispute Settlement System Biased?
(Centre for Economic Policy Research, Economic Research and Analysis Division, Discussion Paper No. 2340,
156 Joseph Francois, Henrik Horn & Niklas Kaunitz, Trading Profiles and Developing Country Participation in the
WTO Dispute Settlement System (International Centre for Trade and Sustainable Development, Issue Paper No. 6,
complaints and the size of its trade and GDP, suggesting that use of the WTO legal system
simply reflects trade patterns and is therefore not biased.
Chad Bown uses a different strategy to examine whether the system’s operation exhibits
bias because of power-oriented factors.157 He looks at which states were the actual complainants
and third parties in WTO disputes in relation to the affected exports, and finds that, controlling
for other factors, a state is less likely to initiate claims when it lacks the capacity to retaliate
against the respondent by withdrawing trade concessions, when it is poor or small, when it has a
preferential trade agreement with the respondent, or when it is especially reliant on the
respondent for bilateral assistance. Similarly, Bruce Blonigen and Bown find that differences in
market power explain patterns of antidumping (AD) protection. They show that a state will less
likely initiate an AD investigation against a state that is likely to initiate a retaliatory AD
investigation, and also that a state is less likely to make a positive injury finding in a domestic
AD case when the target is more likely to initiate a WTO complaint against it in any area of
WTO law.158
Andrew Guzman and Beth Simmons examine the question of whether power or legal
capacity matters more for legal claims through a research design focusing on the identity of the
respondent targeted by a developing state complainant.159 They hypothesize that if market power
matters more, then developing states will tend to bring complaints against weaker opponents
because of less “fear of retaliation” and that if legal capacity matters more, then developing
states will use the scarce resources available to them to target those with larger markets in order
to maximize the payoffs of bringing a claim. They find that each of their proxies for legal
capacity but one (a general “bureaucratic quality” measure) yields a statistically significant
negative coefficient as predicted by the legal capacity hypothesis. In contrast, they find no
support for a market power explanation.
Marc Busch, Eric Reinhardt, and Shaffer examine the impact of legal capacity in
international trade dispute settlement by using a new measure of legal capacity derived from
their survey of WTO members.160 They create a legal-capacity index based on states’ responses
to five questions regarding, respectively: their professional staff, bureaucratic organization at
home, bureaucratic organization in Geneva, experience handling general WTO matters, and
involvement in WTO litigation. The researchers apply this index to assess both the likelihood
that a state will be named in a domestic AD petition and, if so, that such state will challenge the
domestic antidumping suit at the WTO. They find that states that possess greater legal capacity
are both less likely to be targeted by AD duties and more likely to challenge AD duties brought
against them at the WTO. They find that legal capacity affects patterns of WTO dispute initiation
and underlying AD protection among WTO members at least as much as market power, if not
157 Chad P. Bown, Participation in WTO Dispute Settlement: Complainants, Interested Parties and Free Riders, 19
WORLD BANK ECON. REV. 287 (2005).
158 Bruce A. Blonigen & Chad P. Bown, Antidumping and Retaliation Threats, 60 J. INTL ECON. 249 (2003).
159 Andrew Guzman & Beth A. Simmons, To Settle or Empanel? An Empirical Analysis of Litigation and Settlement
at the World Trade Organization, 31 J. LEGAL STUDIES 205 (2002).
160 Marc Busch, Eric Reinhardt & Gregory Shaffer, Does Legal Capacity Matter? A Survey of WTO Members, 8
WORLD TRADE REV. 559 (2009); Marc Busch, Eric Reinhardt & Gregory Shaffer, Does Legal Capacity Matter?
Explaining Dispute Initiation and Antidumping Actions in the WTO (International Centre for Trade and Sustainable
Development, Issue Paper No. 4, 2007).
Empirical studies have also employed qualitative methods to examine what lies behind
the bringing of WTO complaints, such as the role of business and the lawyers that they hire.
Shaffer has done extensive fieldwork and conducted over one hundred interviews at the WTO
and in national capitals to uncover how public and private actors develop cases and use the law
as leverage in bargaining.161 He examines how the WTO legal system has unleashed new
competition for trade law–related expertise, and traces the development of public-private
networks of trade associations, law firms, and government officials in bringing cases and helping
to shape WTO law over time. Joseph Conti has continued important work in this vein, focusing
on how “good cases” are constructed and the role of learning in WTO dispute settlement.162 This
work has formed the basis for discussions in Geneva and different regions to assess options for
building legal capacity to facilitate access to the WTO legal system.
Overall, these studies of invoking the WTO dispute resolution system agree that states’
use reflects their economic size. Large, wealthy states have developed greater legal capacity,
providing them with advantages. Their large markets further provide them with leverage in the
law’s shadow through the greater risk that retaliation poses. Law, in other words, even while it
may constrain the blunt exercise of material power, can also be viewed as an instrument whose
use reflects a form of power. The use of WTO law is conditioned by economic size and the
harnessing of legal capacity, including through the development of public-private partnerships.
Scholars have also empirically assessed whether WTO panels and the Appellate Body are
independent actors in construing the meaning of international trade law. Some scholars contend
that WTO judicial decision makers show a free-trade bias, which does not reflect state
preferences. These studies focus on the winning record of complainants in WTO disputes,
roughly a 90 percent success rate for panel and Appellate Body decisions combined. John and
Caroline Maton use multivariate analysis to show that the complainant advantage in winning
cases is not explained by such external factors as economic power, involvement of third parties,
or status of the complainant as an experienced repeat player.163 Juscelino Colares covers a
broader set of cases, and adds additional control variables, such as case type and subject matter,
party identity, and product type, but uses a bivariate approach.164 He finds that selection effects,
asymmetric incentives, and “playing for rules” cannot explain the finding that complainants win
so often. Instead, he contends that interpretations of the WTO agreements have favored a free-
trade normative vision, indicating biased rule development and providing evidence of judicial
Colares does not, however, examine the possible explanation that respondents are
systematically contesting low-quality cases for domestic political reasons, even though they
know they will lose. That is, respondents may be using WTO dispute settlement to provide
161 SHAFFER, supra note 86; Gregory Shaffer, The Challenges of WTO Law: Strategies for Developing Country
Adaptation, 5 WORLD TRADE REV. 177 (2006); Gregory Shaffer, Michelle Ratton Sanchez & Barbara Rosenberg,
The Trials of Winning at the WTO: What Lies Behind Brazil’s Success, 41 CORNELL INTL L.J. 383 (2008).
ORGANIZATION (2011); Joseph Conti, The Good Case: Decisions to Litigate at the World Trade Organization, 42
LAW & SOCY REV. 145 (2008); Joseph Conti, Learning to Dispute: Repeat Participation, Expertise, and Reputation
at the World Trade Organization, 35 LAW & SOC. INQUIRY 625 (2010).
163 John Maton & Carolyn Maton, Independence Under Fire: Extra-legal Pressures and Coalition Building in WTO
Dispute Settlement, 10 J. INTL ECON. L. 317 (2007).
164 Juscelino F. Colares, A Theory of WTO Adjudication: From Empirical Analysis to Biased Rule Development, 42
VAND. J. TRANSNATL L. 383 (2009).
political cover, attempting to show the affected domestic industry and its political supporters that
the government is doing everything possible to uphold the trade-restrictive measure. The WTO’s
lack of retrospective remedies facilitates this political response because a member can effectively
maintain an illegal trade measure for almost three years of litigation without being subject to any
retrospective legal sanction. Complementary qualitative research would help to explain the
quantitative data.
How and under what conditions WTO law matters. Two questions stand out regarding
whether and, if so, how WTO law matters: does membership affect trade liberalization, and do
states comply with dispute settlement findings affecting trade patterns? First, scholars have
examined the impact of international trade institutions and institutional design on trade patterns
and trade commitments. Andrew Rose’s data controversially suggests that joining the
GATT/WTO does not affect bilateral trade flows—a frontal challenge to neoliberal theory.165
His conclusions have been challenged by Michael Tomz, Goldstein, and Douglas Rivers, who
conclude that the GATT/WTO has a positive trade impact if one includes its effects on colonies,
newly independent states, and provisional applicants as de facto members—which undercuts
Rose’s conclusions.166 Arvind Subramanian and Shang-Jin Wei also find positive trade effects
for industrialized members, although not for others, suggesting that the impact of trade law is
contingent on a state’s trade profile.167
Second, various studies assess the relative efficacy of the WTO/GATT dispute settlement
system in inducing compliance, thereby facilitating trade flows. Robert Hudec’s comprehensive
analysis of GATT dispute resolution shows that the system successfully resolved some 90
percent of legally valid claims.168 Busch and Reinhardt find similarly high success rates of
resolving disputes under the more legalized WTO.169 Importantly, the concessions made in the
wake of WTO decisions appear to matter economically, as shown by Bown.170 Three years after
the date of adoption of a WTO judicial decision in favor of the complainant, and controlling for
other factors, imports of the complainant’s affected goods had increased substantially into the
respondent state. In other words, the party losing the case did not simply replace one form of
protection with another; rather, the successful claim has had tangible effects. In sum, WTO law
and its judicialized system of enforcement provide effective leverage for states to reduce trade
barriers and enhance trade flows. Their ability to do so, however, is conditioned on their
economic size, trade profile, and legal capacity.
165 Andrew K. Rose, Do We Really Know That the WTO Increases Trade?, 94 AM. ECON. REV. 98 (2004).
166 Michael Tomz, Judith Goldstein & Douglas Rivers, Comment, Do We Really Know That the WTO Increases
Trade?, 97 AM. ECON. REV. 2005 (2007).
167 Arvind Subramanian & Shang-Jin Wei, The WTO Promotes Trade, Strongly but Unevenly, 72 J. INTL ECON.
151 (2007). Cf. Jeffrey Kucik & Eric Reinhardt, Does Flexibility Promote Cooperation? An Application to the
Global Trade Regime, 62 INTL ORG. 477 (2008) (finding that states able to take advantage of the WTO’s flexibility
provisions (namely, antidumping laws) tend to agree to more binding tariff commitments and to implement lower
applied tariffs).
SYSTEM (1993).
169 Marc Busch & Eric Reinhardt, Bargaining in the Shadow of the Law: Early Settlement in GATT/WTO Disputes,
24 FORDHAM INTL L. J. 158 (2000).
170 Bown, supra note 16.
International Investment Law
The context of international investment law is both similar to and different from that of
international trade law. They both involve the management of externalities from domestic
regulations affecting foreign firms. However, the investment context, which typically involves
wealthy, industrialized source states and developing host states, is much more asymmetrical and
thus raises distinct distributional issues. This situation is somewhat changing, however, with the
rise of newly industrialized states, potentially affecting the content and operation of investment
law.171 The demand for international investment law is a response to a core feature of domestic
institutional structure: the assumption that local courts will not effectively constrain government
takings of investments owned by foreigners. Economists describe foreign investment as raising a
dynamic inconsistency problem: the host state must make a credible commitment to the foreign
investor that the host will not renege on the deal after the investment has been made.
International dispute resolution helps resolve this problem. The key normative questions debated
are whether international investment law is biased in its formation and application in favor of
exporters of capital, and whether it indeed spurs increased investment that benefits host states.
How investment law is produced. While trade law has effectively been multilateralized,
investment law remains subject to a complex array of bilateral investment treaties (BITs). Earlier
generations of work described the evolution of the regime, but it was Andrew Guzman who
launched a modern research program by asking why we observe a bilateral mode of agreement in
this area of law.172 Guzman explained that developing states are caught in something of a
collective action problem. While they would collectively be better off if they could negotiate a
multilateral treaty, each individual developing state has an incentive to defect from the collective
group so as to capture a greater share of the overall pool of investment. This situation spurs, in
effect, a race to liberalize foreign investment law. Economically poor states conclude bilateral
agreements that reduce their options for regulating investment. These agreements differ from
any agreements that would be negotiated multilaterally.
BITs concluded between rich and poor states grew dramatically in the 1990s. Zachary
Elkins, Simmons, and Guzman examine the spread of BITs to test, and ultimately support,
Guzman’s hypothesis that developing states compete against each other to conclude BITs with
capital exporters.173 They also find interesting evidence of diffusion-based explanations; for
example, cultural similarity and security relationships explain which pairs of states are likely to
conclude BITs. These arrangements thus represent a response to the different character of
investment as opposed to trade, and illustrate some of the conditions under which multilateralism
will lose out to bilateralism—which is important for conditional IL theory.
Similarly, scholars have debated whether the application of investment arbitration
exhibits structural bias. Susan Franck is conducting an ongoing empirical study of the field using
171 See, e.g., José E. Alvarez, The Return of the State, 20 MINN. J. INTL L. 223, 237–38 (2011) (discussing changes
in model BITs).
172 Andrew Guzman, Why LDCs Sign Treaties That Hurt Them: Explaining the Popularity of Bilateral Investment
Treaties, 38 VA. J. INTL L. 639 (1998).
173 Zachary Elkins, Andrew Guzman & Beth A. Simmons, Competing for Capital: The Diffusion of Bilateral
Investment Treaties, 1960–2000, 60 INTL ORG. 811 (2006).
quantitative analysis.174 While this area is still plagued by a small n and selection problems
(since not all awards are published or reported), she finds that the nationality of the presiding
arbitrator does not make a difference for outcomes, indicating an absence of bias against
developing states.175 One might question, however, whether the arbitrator’s nationality is an
appropriate proxy for bias in the investment law context since ideology and professional
competition may affect the selection of the few developing state arbitrators in question.176
Dezalay and Garth conducted extensive fieldwork and interviewing of arbitrators to show the
intense competition between potential sites of arbitration and between American and European
arbitrators—both of which have helped to shape the development of arbitration law and to
establish its legitimacy.177 This legitimacy is increasingly disputed, however—for example, in
relation to a series of challenges to arbitration awards against Argentina while it was mired in a
financial crisis.178 New studies need to assess how the system adapts to respond creatively to
such situations.
How and under what conditions international investment law matters. The key normative
question regarding the impact of BITs is whether they actually attract increased investment flows
between the contracting states, and if so, with what impact. Empirical work is providing
important new data for this analysis. Jason Yackee finds no positive relationship between the
strength of investor protection in BITs and investment flows.179 He gives a socio-legal
explanation that investors often are ignorant of the law or that, because of reputation concerns,
they use other nonformal means to resolve disputes.180
By contrast, a competing theory is that BITs provide “credible commitments” when
foreign investors have grounds to believe that a state’s domestic legal system is inadequate and
thus cannot be trusted to uphold a contractual bargain.181 To test the hypothesis about credible
174 Susan Franck, Development and Outcomes of Investment Treaty Arbitration, 50 HARV. INTL L.J. 435 (2009);
Susan Franck, Empiricism and International Law: Insights for Investment Treaty Dispute Resolution, 48 VA. J.
INTL L. 767 (2008); Susan Franck, Empirically Evaluating Claims About Investment Treaty Arbitration, 86 N.C. L.
REV. 1 (2007).
175 Susan Franck, Development and Outcomes of Investment Treaty Arbitration supra note 174; see also Daphna
Kapeliuk, The Repeat Appointment Factor: Exploring Decision Patterns of Elite Investment Arbitrators, 96
CORNELL L. REV. 47, 47 (2010) (finding that repeat arbitrators “display no biases and no tendencies to ‘split the
difference’ ”).
176 See also Gus Van Harten, Reply, 2010–2011 Y.B. INTL INVESTMENT L & POL. (forthcoming) (replying to Susan
Franck, Calvin Garbin & Jenna Perkins, Response: Through the Looking Glass: Understanding Social Science
Norms for Analyzing International Investment Law, in same volume).
177 DEZALAY & GARTH, supra note 71.
178 William W. Burke-White, The Argentine Financial Crisis: State Liability Under BITs and the Legitimacy of the
Waibel, Asha Kaushal, Kyo-Hwa Liz Chung & Claire Balchin eds., 2010) (arguing that the recent decisions
involving the U.S.-Argentine BIT threaten the legitimacy of the investor-state arbitration system); William W.
Burke-White & Andreas von Staden, Private Litigation in a Public Law Sphere: The Standard of Review in
Investor-State Arbitrations, 35 YALE J. INTL L. 283, 285 (2010) (“the perceived legitimacy of investor-state
arbitration has come under threat in recent years in the eyes of some states” (footnote omitted)).
179 Jason W. Yackee, Bilateral Investment Treaties, Credible Commitment, and the Rule of (International) Law: Do
BITs Promote Foreign Direct Investment?, 42 L. & SOC. REV. 805 (2008).
180 Id.
181 Cf. Tom Ginsburg, International Substitutes for Domestic Institutions: Bilateral Investment Treaties and
Governance, 25 INTL REV. L. & ECON. 107 (2005) (finding little improvement in institutional quality after
entering into a BIT, suggesting that international commitment devices can substitute for, rather than complement,
commitments, a number of quantitative studies have assessed whether BITS and investment
flows are related; the results are mixed.182 Each of these studies uses different control variables,
such as wealth, institutional quality, and concentration of natural resources, and the econometric
specifications also vary. While competition in the academy often depends on scholars staking out
and defending a position, it would be productive for the various scholars in the BIT debates to
work together to sort out and reconcile their results.
Tim Büthe and Helen Milner take a unique tack in assessing the role of international law
on investment flows. They apply credible commitments theory and find that membership in
multilateral and preferential trade agreements results in increased investment into the state
parties.183 They contend that such membership provides information that helps to assure
investors of domestic political stability. Applying a similar argument in a comprehensive survey
of existing empirical work on BITs, these authors find that BITs help signal commitment to a
whole range of liberal policies and thus improve all investment flows into the host states
regardless of the source, and not simply the flows between the BIT parties.184
In sum, the BIT literature addresses the midlevel theoretical concept of credible
commitments, and demonstrates the sensitivity of empirical work to different specifications. The
discrepancies in existing studies may be explained by their use of different measures of
investment flows, as well as different estimation techniques. Studies focusing on only bilateral
investment flows between BIT parties find that BITs have little impact, whereas studies focusing
on overall investment flows into BIT parties find that they have positive effects. The authors of
the latter studies provide evidence that becoming a party to a BIT creates general signals for
foreign investors regarding a state’s commitments to investor protection. While the large-N
evidence may be leading in the direction of consensus, the signaling story calls out for qualitative
work on foreign investment decisions to better understand the conditions under which decision
makers respond to legal change.
domestic institutions); Jennifer Tobin & Susan Rose-Ackerman, Do BITs Benefit Developing Countries?, in THE
FUTURE OF INVESTMENT ARBITRATION (Roger P. Alford & Catherine Rogers eds., 2009) (finding that BITs serve
as complements).
182 Id. Cf. Rashmi Banga, Impact of Government Policies and Investment Agreements on FDI Inflows (Indian
Council for Research on International Economic, Working Paper No. 116, 2003) (positive effect); M. Busse, J.
Koeniger & P. Nunnenkamp, FDI Promotion through Bilateral Investment Treaties: More Than a BIT? (Kiel
Institute for the World Economy, Working Paper No. 1403, 2008) (positive effect); Tim Büthe & Helen V. Milner,
The Politics of Foreign Direct Investment into Developing Countries: Increasing FDI Through International Trade
Agreements?, 52 AM. J. POL. SCI. 741 (2008) (positive effect); K. P. Gallagher & M. B. I. Birch, Do Investment
Agreements Attract Investment? Evidence from Latin America, 7 J. WORLD INV. & TRADE 961 (2006) (no increase
in U.S. investment); Mary Hallward-Driemeier, Do Bilateral Investment Treaties Attract Foreign Direct
Investment? (World Bank Policy Research, Working Paper No. 3121, 2003) (no effect); Eric Neumayer & Laura
Spess, Do Bilateral Investment Treaties Increase Foreign Direct Investment to Developing Countries?, 33 WORLD
DEV. 1567 (2005) (positive effect); Jeswald W. Salacuse & Nicholas P. Sullivan, Do BITS Really Work?: An
Evaluation of Bilateral Investment Treaties and Their Grand Bargain, 46 HARV. INTL L.J. 67 (2005) (positive
effect); Tobin & Rose-Ackerman, supra note 181; Yackee, supra note 179 (no effect of strong BIT). Each of these
studies uses a slightly different approach.
183 Büthe & Milner, supra note 182.
184 Tim Büthe & Helen V. Milner, Bilateral Investment Treaties and Foreign Direct Investment: A Political
International Environmental Law
International environmental law is a growing field of study that faces its own special
challenges, especially in relation to transboundary environmental externalities and regulating the
global commons. These challenges often involve considerable scientific and technical
complexity regarding the diagnosis of a problem, its causes, and the implications of regulatory
alternatives. International environmental law also has differential distributive implications for
states and private stakeholders, rendering the politics of lawmaking especially salient. For
example, while many states lose from climate change, others arguably win, and in any case the
cost of mitigating climate change varies in light of national economies’ relative dependence on
fossil fuels. Starting with the Trail Smelter Case,185 which conceived of transboundary
environmental pollution in a bilateral framework akin to domestic nuisance law, environmental
concerns have entered many areas of international law, including trade law, the law of the sea,
and even the law of war. These particular attributes of international environmental law call, once
more, for greater attention to contextual, midrange theorizing. Among the most interesting issues
for empirical study is the role of nonstate actors and of soft law in the production of international
environmental law and in its impact.
How international environmental law is produced. Work that treats environmental law as
a distinct field has expanded significantly in the last two decades. Scholars have compiled and
compared numerous qualitative case studies by using the method of process tracing to determine
how international environmental law is created in particular areas.186 Collectively, these studies
show that environmental regimes frequently start as disappointments but that they can create, in
John Braithwaite and Peter Drahos’s words, a “contractual environment” into which mass
concern can be channeled later, as in the wake of a major news event.187 Through these regimes,
soft and hard law are often developed in stages, with national capacity built to address the
particular environmental concerns at stake at any particular point.
Nongovernmental actors frequently play major roles in the politics of international
environmental lawmaking, including by heightening global concern about the environment and
185 Trail Smelter Case (U.S. v. Can.), 3 R.I.A.A. 1905 (1941). For an excellent overview of international
environmental law, see BODANSKY, supra note 38.
(Robert Keohane, Peter Haas & Marc Levy eds., 1993) (case studies of seven international environmental
Osherenko eds., 1993) (building from five case studies on the formation of environmental regimes for the Arctic to
test hypotheses regarding regime formation); THE IMPLEMENTATION AND EFFECTIVENESS OF INTERNATIONAL
ENVIRONMENTAL COMMITMENTS (David Victor, Kal Raustiala & Eugene B. Skolnikoff eds., 1998) (fourteen
WITH EVIDENCE (2002) (reviewing the effectiveness of fourteen regimes as a function of the character of the
problem and the problem-solving capacity to address it; combining qualitative and quantitative analysis; and tracing
the incremental stages of the regimes’ formation, implementation, and impact); RONALD B. MITCHELL,
187 BRAITHWAITE & DRAHOS, supra note 147, at 618–20; see also Ronald B. Mitchell, International Environmental
Agreements: A Survey of Their Features, Formation, and Effects, 28 ANN. REV. ENVT & RES. 429 (2003).
by framing the issues to be addressed.188 Private actors, whether they are NGO activists,
businesses, or knowledge-based epistemic communities such as scientists and members of
particular professions, work both with states and independently of them to shape perceptions of
international environmental problems and solutions. Socio-legal scholars Penelope Canaan and
Nancy Reichman, for example, use extensive participant-observation and interviews to assess the
role of epistemic communities, such as scientists, in the development and implementation of the
1987 Montreal Protocol on Substances That Deplete the Ozone Layer.189 This work has laid
some basis for studying the crucial case of climate change, a paradigmatic global problem for
which the problems of regime formation are especially acute. In this latter case, however, there
have been sustained attempts to delegitimize scientists in light of the influence that they can
potentially exercise.
NGOs have also been central in creating private and hybrid consumer-oriented regimes to
overcome the limitations of state-built alternatives—spurring new research on how these regimes
were constructed.190 Ben Cashore and Errol Meidinger, for example, show how transnational
civil society networks have created new transnational forest-stewardship norms and institutions
to enforce them.191 They assess the role of these networks in defining and implementing soft law
standards, including through labeling regimes that convey whether lumber has been harvested in
an environmentally sustainable manner. These civil society programs frequently stimulate
competition by business-based programs, generating, in turn, dynamic processes of competitive
standard setting.192
There is some movement toward building databases for more quantitative analysis in this
area, as evidenced by the creation of the International Regimes Database, which facilitates the
comparison of specific aspects of international environmental regimes.193 For example, Denise
Degarmo has tested a series of variables to predict the probability that a state will become party
to a multilateral environmental agreement; she finds that more open, free governments are more
SIKKINK, supra note 104.
189 Sept. 16, 1987, S. Treaty Doc. No. 100-10 (1987), 1522 UNTS 3; see PENELOPE CANAN & NANCY REICHMAN,
David W. Cash & Nancy M. Dickson eds., 2006); Peter Haas, Banning Chlorofluorocarbons: Epistemic Community
Efforts to Protect Stratospheric Ozone, 46 INTL ORG. 187 (1992).
190 See, e.g., WAPNER, supra note 188.
191 See, e.g., Abbott & Snidal, supra note 59; Errol Meidinger, The Administrative Law of Global Private-Public
Regulation: The Case of Forestry, 17 EUR. J. INTL L. 47(2006); Cashore et al., supra note 59.
192 Civil society groups, moreover, also divide on environmental issues, as North- and South-based NGOs often
disagree on the appropriate approaches for addressing environmental problems at the international level, particularly
regarding the legitimacy of unilateral trade measures imposed by large states—a point that is often elided by
normatively oriented legal scholars. See Judith Mayer, Environmental Organizing in Indonesia: The Search for a
GOVERNANCE 169 (1996); Gregory Shaffer, The World Trade Organization Under Challenge: Democracy and the
Law and Politics of the WTO’s Treatment of Trade and Environment Matters, 25 HARV. ENVTL. L. REV. 1, 68–74
(2001) (building from interviews and systematic review of minutes of WTO committee meetings).
likely to become parties, 194 which resonates with the work we cited earlier in other domains,
highlighting the potential broader implications of context-specific studies.
How and under what conditions international environmental law matters. The work on
the impact of international environmental law faces the challenges raised by Downs and
colleagues regarding international law generally—that is, whether international law requires
states to do more than they already plan. The impact of international environmental law can be
assessed in terms of formal changes in national law, changes in actors’ behavior, and changes in
environmental quality.195 Environmental advocates are clearly most concerned about the ultimate
impact of international environmental law and about mechanisms that can be adapted to enhance
that impact. Empirical studies have addressed both compliance with, and the effectiveness of,
international environmental agreements.196
The impact of international environmental law is typically context specific. What needs
to be taken into account are the characteristics of the activity, the characteristics of the accord,
the international environment, and domestic factors, as shown by Edith Brown Weiss and Harold
Jacobson in their study regarding the compliance of eight states and the European Union with
five international environmental agreements.197 A key issue is how to enhance the impact of
international law over time. Following Chayes and Chayes’ work,198 many environmental law
scholars have advocated a “managerial approach” in which agreements maximize inclusiveness
but minimize initial commitments and deemphasize enforcement; the rationale is that through
ongoing state interaction, states’ positions will gradually transform, leading to deeper
cooperation. Soft law mechanisms are often advocated in such circumstances. From a series of
fourteen case studies involving eight issue areas, David Victor, Kal Raustiala, and Eugene
Skolnikoff conclude that, although compliance with legally binding agreements is high, states
often agree only to modest commitments, with which they can easily comply. In contrast, the
researchers find that nonbinding agreements can be more ambitious in the change envisaged and
can have a greater influence on changing state behavior.199 This latter conclusion has been
supported by some scholars, who have combined qualitative and quantitative methods to
document how a number of effective regimes have followed incremental, stage-based pathways
to greater cooperation.200 But that conclusion has also been disputed—for example, by Downs,
Kyle Danish, and Barsoom, based on their review of state responses to agreements fitting the
“transformational model” relative to others.201 Further empirical work is needed that assesses the
conditions under which an incremental, transformative approach is more likely to be effective.
194 DEGARMO, supra note 56.
186, at 5–7.
(Edith Brown Weiss & Harold K. Jacobson eds., 1998); MILES ET AL., supra note 186; ORAN YOUNG,
Effect of International Environmental Institutions: How We Might Learn More, 49 INTL ORG. 351 (1995).
197 ENGAGING COUNTRIES, supra note 196.
198 CHAYES & CHAYES, supra note 7.
200 See, in particular, MILES ET AL., supra note 186.
201 George W. Downs, Kyle W. Danish & Peter N. Barsoom, The Transformational Model of International Regime
Design: Triumph of Hope Or Experience?, 38 COLUM. J. TRANSNATL L. 465 (2000).
Finally, environmental law scholars have attended to mechanisms that harness the
incentives of the private sector and lead to environmental improvements. Ronald Mitchell’s
leading study of oil pollution at sea stands out in this respect.202 He finds that obligations placed
on states to prosecute violators were relatively unsuccessful in stemming oil discharges but that a
particular provision regarding the installation of specified equipment on oil tankers had the
greatest impact. It did so because it expanded the target for enforcement to include not just states,
but also insurance-classification societies and shipbuilders. Insurers insure only ships that are
classified as satisfying certain standards, such as the segregation of ballast tanks, which is critical
for reducing oil pollution at sea.203 The use of a broad-based compliance system, moreover,
increased transparency and reduced implementation costs, deterring violations. Similarly, Aseem
Prakash and Mathew Potoski show the importance of harnessing the private sector in their study
of the relation between trade and a voluntary international business standard regarding
environmental management systems (ISO 14001).204 They find that trade linkages encourage
businesses’s adoption of the standard within a state if the standard is adopted in the state’s major
export markets. In short, empirical studies in international environmental law stress the
importance of disaggregating the state in analyzing how international law becomes effective— in
this case through harnessing the private sector.
Empirical work is not atheoretical. Rather, in line with the emergent analytics we have
stressed, empirical work is central to building what we have termed conditional IL theory—that
is, midlevel theory that is sensitive to the varying contexts in which international law operates
and that addresses the conditions under which international law is produced and has effects.
From the perspective of conditional IL theory, we have stressed the different types of
situations that international law involves, such as collective action problems, externalities,
cooperation and coordination challenges with distributive implications, and expressive norms
regarding right conduct within a broader community (see Table 1). What has been called the
fragmentation of international law reflects these different challenges and the political and social
contexts in which states and nonstate actors operate. As a result of these diverse factors, some
areas of international law are characterized by a web of bilateral treaties (as in investment and
tax law), and others characterized by a multilateral approach or a mix of multilateral and bilateral
approaches (as in human rights and international trade law). In some areas soft law is seen as
desirable and effective in facilitating patterns of cooperation (as in environmental law); in others,
hard law and third-party dispute settlement are seen as central for inducing compliance (as in
trade law). Similarly, international law’s impact varies in light of the different underlying
conditions and institutions characterizing these different subject areas; for example, compare the
202 Ronald Mitchell, Regime Design Matters: Intentional Oil Pollution and Treaty Compliance, 48 INTL ORG.
425 (1994).
203 See discussion in BRAITHWAITE & DRAHOS, supra note 147, at 618.
204 Aseem Prakash & Matthew Potoski, Racing to the Bottom? Trade, Environmental Governance, and ISO 14001,
50 AM. J. POL. SCI. 350 (2006) (drawing on a panel study of 108 states over seven years). For interesting empirical
work on industry self-regulation, see Michael Lenox, The Prospects for Industry Self-Regulation of Environmental
high politics of humanitarian law, which can involve state survival and elite power struggles,
with trade law, which does not). In light of this diversity, grand theory is not helpful. Without
attention to context, theorizing will be of little pragmatic use.
We have reviewed the major empirical findings in the recent literature across five
important areas of international law. These areas, of course, are hardly exhaustive, but they do
represent a range of important problems where international law has developed and can be
useful. Table 1 summarizes our review of each of the five areas covered in Part III. We identify
the area’s core problem structure, note the chief questions that have motivated empirical study to
date, and list some conditional findings regarding the parameters that determine whether
international law is produced and when international law is effective.
Table 1: Summary of Problem Types, Empirical Questions and Findings
Rights Humanitarian
and Criminal
Trade Investment Environment
Expressive of
norms High Politics;
Action (PD)
Action (PD
and BOS)
Action (Global
Distrib Conflict
Major topic
of research
on how IL is
Reasons for
and operation
of tribunals;
Presence of
Role of
of states to
Presence of
bias in
Reasons for
bilateral vs.
Presence of
Reasons for
processes of
Soft vs. hard
law; Role of
non-state actors
Major topic
of research
on how IL
Impact of
ratification on
Effects on
deterrence and
on post-
Effect of law
on trade
Effect on
Impact of
ratification on
IL finding Domestic
matter for
and impact;
nature, regime
type, timing &
tribunal design
all affect
Time horizon
capacity is
for exercise
of leverage
in disputes;
leads to
evidence on
direct effects,
but BITs and
communities &
NGOs matter
in framing;
Private sector
matters in
Civil society
is key shaper,
conveyor &
translator of
for evaluation
matters for
impact of trials
and amnesties,
alone & in
power is
important in
rules and
FTAs work as
signals to
Soft law
matters on own
& as part of
Conditional IL theory focuses on the different mechanisms through which international
law is produced and has its effects in different domains. As we have noted, the mechanism of
reciprocity is central to international trade law, but not to human rights law, in which expressive
and norm-conveying mechanisms play a primary role. In contrast, the mechanism of competition
is central to the development of international investment law. For environmental standard setting,
the mechanism of modeling often plays a more significant role.205 This point regarding the study
of mechanisms has great practical value since the tools to make international law effective often
will be specific to particular domains and contexts, whether involving international human rights
or trade or environmental law, or different states in different areas of the world.
Notwithstanding the importance of problem type in determining what mechanisms might
be effective, future empirical work may find it valuable to borrow research questions and
approaches from areas of law with different problem types. Table I highlights the predominant
questions pursued in different issue areas to date. For example, as we have noted, extensive
ethnographic work has been conducted concerning international criminal tribunals, but not WTO
panels. By contrast, the WTO literature, though not the investment literature, has thoroughly
analyzed the conditional decision by a state to bring claims. Writing on investment law has
focused, instead, on the macro question of whether BITS increase investment flows—even
though the decision to initiate an investment arbitration is interesting as well. Our suggestion is
that understanding the conditions under which international law is produced and is effective in
one area can generate research questions about other areas, helping, in turn, to identify the
factors that generate similar or different outcomes.
Another strategy for conditional IL theory is to disaggregate groups of states in order to
focus on the characteristics of, and factors within, states that help to explain the influence of
international law—as reflected in the work of Beth Simmons, Oona Hathaway, Kathryn Sikkink,
and others.206 International law does not matter for all states all the time, but that does not mean
that it does not matter. The burgeoning empirical literature that we have discussed helps to
explain how the effectiveness of international law is linked to the characteristics of states and
their institutions and social contexts. It would be especially useful to see more work along these
lines in international trade and investment and environmental law. Case studies of marginal states
in which compliance with, or use of, international law is not overdetermined could potentially
help to tease out possible causal relationships.
205 We also address the use of mechanisms in Ginsburg & Shaffer, supra note 69. There we also cover regulatory
standard setting, where the mechanism of modeling is again important. See also BRAITHWAITE & DRAHOS, supra
note 147, at 532–49; Halliday & Osinsky, supra note 23.
206 See, e.g., SIMMONS, supra note 1, pt. III.A, III.B; Hathaway, supra note 95; Kim & Sikkink, supra note 141.
Conditional IL theorists sometimes focus on states, but even when they do, they also tend
to disaggregate the state and study the role of networks, firms, and civil society as actors that
affect state compliance. Many empirical studies—in all of the areas we analyze—show that
nonstate actors and subdivisions within the state play key roles, both in producing international
legal norms and in communicating and implementing them within states, including by reframing
them in light of local social contexts. Theories of international law that are purely state-centric
may be parsimonious, but this empirical work highlights their limits, especially where legal
norms are appropriated and hybridized by local actors for their own local ends.207 This work also
points to the importance of studying the production of soft law and how such lawmaking
interacts with more conventional forms of international lawmaking.
The production and impact of international law, to borrow from the social theorist Robert
Merton, “cannot be usefully posited in advance of observation. It is a question of fact, and not a
matter of opinion.”208 This point is of great pragmatic, normative importance. For conditional IL
theorists building from empirical work, international lawyers should avoid prescriptions that are
based solely on theoretical positions rather than ones also grounded in empirical investigations.
As recently as two decades ago, empirical work on international law was rare. Scholarly
discourse tended to be segmented, with proponents of international law conducting internal
debates about law and legal cases, and IR scholars paying little attention to law, focusing instead
on t