Technical ReportPDF Available

Gun Violence in America



This report examines the history of guns in the United States, the prevalence of gun violence in our communities, trends in mass shootings, and the rise of “performance violence” in an age of social media. This report also analyses what works in gun violence prevention and intervention.
Gun Violence in America
James A. Densley & Jillian K. Peterson
Issue Brief 2017-01
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
About The Violence Project
The Violence Project LLC provides consulting, research, evaluation, and
training on criminal justice issues. We also provide white papers such as this that
provide analyses of pressing social or policy issues. Our aim is to reduce crime and
violence in our communities. On behalf of cities, counties, states, federal agencies,
private and non-profit organizations, we develop new programming, design and
conduct evaluations, and analyze the effectiveness of programs and policies. Visit us
About This Violence Project
Gun Violence in America was produced to enhance an October 2017 public
forum at Hamline University titled, “Making Sense of the Violence in Las Vegas.” It
extends work from a March 2013 Deliberative Dialogue on Gun Violence in
America,” hosted by Metropolitan State University.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
About the Authors
James A. Densley is Associate Professor of Criminal Justice at
Metropolitan State University. Since completion of his PhD in sociology at the
University of Oxford, Densley has quickly established himself as one of the world’s
leading experts on street gangs and youth violence, and a prominent voice locally
on issues of peace officer education and training. He is the author of the award-
winning How Gangs Work (Palgrave Macmillan, 2013), and co-author of the
textbook, Minnesota’s Criminal Justice System (Carolina academic Press, 2016). In
addition, he has published more than 30 refereed articles and book chapters in
leading social science outlets, and op-eds for CNN, MinnPost, StarTribune, The Sun,
and The Wall Street Journal. His work has attracted local, national, and international
media attention, most recently for being a co-signatory on a letter to the media
urging them to stop publishing the names and photographs of mass killers.
Jillian K. Peterson is Assistant Professor of Criminology and Criminal
Justice at Hamline University. Jill launched her career as a special investigator in
New York City, investigating the bio-psycho-social life histories of men facing the
death penalty, which were used in their sentencing hearings. Jill has a Master’s
Degree in social ecology and a PhD in psychology and social behavior from the
University of California, Irvine. She has led large-scale research studies on mental
illness and crime, school shooting prevention strategies, and mass violence, which
have received national media attention. She is a sought-after trainer and speaker on
issues related to mental illness and violence, trauma, cyber-violence, the
development of crime and violence, and forensic psychology. Jill is trained in
restorative justice, violence mediation, crisis intervention, de-escalation, and suicide
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
Gun Violence in America
James A. Densley, Ph.D.
Jillian K. Peterson, Ph.D.
© 2017. This paper is covered by the Creative Commons “AttributionNoDerivsNonCommercial” license (see It may be reproduced in its entirety only if The Violence Project LLC is credited, a link
to the Project’s website is provided, and no charge is imposed. The paper may not be reproduced in part or in
altered form, or if a fee is charged, without the Project’s permission. Please let the Project know if you reprint.
Suggested citation:
Densley, J. & Peterson, J. (2017). Gun violence in America. St. Paul, MN: The Violence Project LLC.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
Executive Summary
On October 1, 2017 at 22:05 local time, a gunman opened fire on concertgoers
below his 32nd floor hotel room in Las Vegas, killing at least 58 people and injuring
almost 500. The attack is considered the deadliest mass shooting in recent US
history. It has renewed debate about gun violence and gun control. This issue brief
adds context to potential policy proposals. Key takeaways include:
Owing to the Second Amendment, the United States has a long history of
private gun ownership both for common defense and self-defense
The US has by far the highest rates of gun ownership in the world
Attitudes to gun rights and gun control are strictly partisan
The mere presence of guns underlies tensions between law enforcement and
the community
The US has the highest rate of gun homicides among advanced countries
Even as gun ownership increases, gun violence (in the long term) is declining
Gun violence concentrates not just spatially, but also socially
The vast majority of people with mental illness are not violent
Ex post facto explanations and an excess of false positives make predicting
mass shooters difficult
Performance violence enacted in the pursuit of fame or notoriety is an
important factor in public mass shootings
40 percent of gun sales occur in the “secondary market” where federal law
does not require transaction records or criminal background checks
Reducing criminals’ access to firearms can reduce the level of criminal
violence with firearms.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
Part 1: The Nature and Extent of the Problem
A Brief History of Guns in America
Adopted on December 15, 1791, as part of the first ten amendments
contained in the Bill of Rights, the Second Amendment of the United States
Constitution reads:
A well-regulated militia, being necessary to the security of a free State,
the right of the people to keep and bear arms, shall not be infringed.
Sir William Blackstone, author of the seminal Commentaries on the Laws of
England (1765), described this right as an “auxiliary right,” that is, a mechanism to
protect the natural or inherent rights of self-defense, resistance to oppression, and
the civic duty to act in concert in defense of the state. At this time, “arms” were
military weapons and those used by a “well-regulated militia” when the Second
Amendment was first proposed in 1789 were mostly long arms that could discharge
only once before they had to be reloaded; very different from the arms of today
(Lepore, 2012).
During the Revolutionary War (1775–83), militiamen were largely dependent
on publicly supplied muskets with bayonets. The Second Amendment was ratified
post-war in case the federal government should neglect to sufficiently arm and
discipline the citizen militia. The danger was not a tyrannical federal government
bent on disarming the people, but rather the people disarmed because of federal
inaction (Sweeny & Saul, 2013). In 1792, federal law mandated every eligible man to
purchase a military-style gun and ammunition for his service in the newly established
Uniform Militia. The intent was “National Defense,” but most state militias still
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
lacked the firepower common in regular military service, to the extent that their
arsenal was better suited to “birding, hunting, and pest control” (Sweeny & Saul,
Owing to public opposition to standing armies, the Continental Army formed
by the Second Continental Congress in 1775 was disbanded after the 13 colonies
won independence (per Article 1, Section 8 of the Constitution). As a result, the
War of 1812, the MexicanAmerican War (184648), the Civil War (186165), and
the 1898 Spanish-American War were fought primarily by state militias called into
temporary federal service. By the middle of the Nineteenth Century, the United
States had a standing army but it took mobilization of National Guard units coupled
with a massive conscription effort to create a force large enough to fight World
War I (191418) and World War II (193945) overseas.
Only after WWII did a large (and well-funded) standing army become a
permanent fixture of the American landscape. An active-duty army swelled with
over 2 million conscripts fought The Vietnam War (195575) because the National
Guard was too busy fighting insurrection at home. And a standing army blended
with state militia forces (e.g., National Guard and Army Reserve) fought the Persian
Gulf War (199091) and more recent conflicts in Afghanistan (2001present) and
Iraq (200311).
When the American Civil War ended in 1865, demobilized Union and
Confederate troops were permitted to take home their arms. This establishes a
base for the modern culture of personal weapons. The National Rifle Association
(NRA) was founded in 1871, in part to promote firearms safety education and
marksmanship training for this new generation of gun owners. For most of its
history, the NRA was chiefly a sporting and hunting association (Winkler, 2013).
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
The NRA endorsed both the 1934 National Firearms Actthe first major
federal gun lawand the 1938 Federal Firearms Act, which together created a
licensing system for dealers and imposed tax and registration requirements on
“gangster guns” (e.g., machine guns and sawed-off shotguns) used by prohibition-
era organized criminals. The National Firearms Act also effectively banned the sale
and possession of silencers, something that Congress is currently revisiting. When
President John F. Kennedy was assassinated in 1963 and the gun responsible was
found to have been purchased via a mail-order advertisement in the NRA’s American
Rifleman magazine, the organization’s Executive Vice President even testified in
favor of banning mail-order rifle sales, noting “We do not think that any sane
American, who calls himself an American, can object to placing into this bill the
instrument which killed the president of the United States” (as cited in Winkler,
2013). However, the 1968 Federal Gun Control Act, enacted after the
assassinations of Robert F. Kennedy and Martin Luther King, Jr. that same year,
which banned mail-order sales, prohibited gun dealers from selling to “dangerous”
categories of persons (e.g., juveniles, convicted felons, drug users, former mental
patients), and restricted the importation of military-surplus firearms, divided the
Gun ownership was specifically preserved by the founding fathers in the
interest of the common defense against a tyrannical government. By the 1960s,
however, establishing a constitutional right to carry a gun for the purpose of self-
defense was slowly becoming central to the mission of the Black Panther Party.
Inspired by Malcolm X’s call for self-defense “by whatever means necessary”, Huey
Newton, Bobby Seale, and other young African Americans very publicly tested a
California law that allowed people to carry guns in public providing they were visible
and not pointed at anyone in a threatening way (Winkler, 2013). In doing so, the
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
Black Panther Party took the instrument that once enforced Jim Crow and white
supremacy and turned it into a symbol of black empowerment. Subsequent law-
and-order legislation that disarmed black radicals under the auspices of fighting
crime and controlling civil unrest was last straw for the NRA (Densley, 2016).
Following a coup d'état at the NRA’s annual membership meeting in 1977, the NRA
began advancing the argument that the Second Amendment guarantees an
individual’s right to carry a gun as a means of self-defense, rather than the people’s
right to form armed militias to provide for the common defense.
The idea that owning and carrying a gun is both a fundamental American
freedom and an act of citizenship has only gained wide acceptance in the decades
since. In 1986, the NRA’s interpretation of the Second Amendment achieved new
legal authority with the passage of the Firearms Owners Protection Act, which
repealed parts of the 1968 Gun Control Act by invoking “the rights of citizens
to keep and bear arms under the Second Amendment.” Individual states, in turn,
widely adopted “concealed carry” and “stand your ground” legislation, the latter
pertaining to an extension of the so-called castle doctrine, exonerating from
prosecution citizens who use deadly force when confronted by an assailant, even if
they could have retreated safely.
Finally, in 2008, in District of Columbia v. Heller, the Supreme Court ruled
unconstitutional, Washington D.C.’s Firearms Control Regulations Act of 1975;
specifically, a ban on handguns and prohibition of long guns for self-defense. The
Heller decision expanded the scope of Second Amendment to the possession of
firearms for the purpose of personal self-defense. However, the majority opinion,
written by conservative Justice Antonin Scalia, states:
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
Like most rights, the right secured by the Second Amendment is not
unlimited. It is not a right to keep and carry any weapon whatsoever
in any manner whatsoever and for whatever purpose. Nothing in
our opinion should be taken to cast doubt on longstanding prohibitions
on the possession of firearms by felons and the mentally ill, or laws
forbidding the carrying of firearms in sensitive places such as schools
and government buildings, or laws imposing conditions and
qualifications on the commercial sale of arms.
In other words, Justice Scalia, the champion of originalism, embraced a living
Constitution (Winkler, 2013).
The Politics of Gun Control
A Gallup (2016) poll found that 58 percent of Americans had a very or mostly
favorable opinion of the NRA; whereas 35 percent have a mostly or very
unfavorable view. Attitudes were partisan: in 2015, 68 percent of Democrats
maintained that the NRA has too much influence over gun debates; compared to
13 percent of Republicans (Pew Research Center, 2016). There are certainly two
sides to the gun debate. The NRA generally advocates for Second Amendment
rights and freedoms, including gun ownership for self-defense; American heritage
and culture, thereby normalizing the use of firearms in society; and safety and law,
predicated on the idea of responsible gun ownership. The Brady Campaign, the
leading gun control lobby, promotes public health and safety (i.e., the notion that
gun violence is preventable); crime control (i.e., regulating guns will reduce criminal
activity); and the rights of municipal governments to regulate guns and hold gun
manufacturers accountable for violence perpetrated with their products. It is worth
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
noting that the 2005 Protection of Lawful Commerce in Arms Act (PLCAA),
effectively shields gun manufacturers and sellers from civil claims brought by victims
of gun violence.
A significant majority of the American public opposes an outright ban on
guns, according to polling by Gallup. The “gun control paradox” (Goss, 2006),
however, is that a similar majority do favor some restrictions on firearms, but policy
proposals to this effect appear dead on arrival in Congress. One Gallup (2016) poll
found that 55 percent of Americans favored stricter gun laws, compared to 33
percent who felt laws should remain the same, and 11 percent who wanted laxer
laws. In another survey from Pew Research Center (Oliphant, 2017), some specific
controls were widely supported by people across the political divide, including
restricting the sale of guns to people who are mentally ill, or on “no-fly” or “watch”
lists, and universal background checks. But Republicans and Democrats are much
more divided over other policy proposals, such as whether to allow ordinary
citizens increased rights to carry concealed weapons.
Gun Ownership in America
The United States has by far the highest rate of gun ownership in the world.
There are an estimated 270 million civilian-owned firearms in the United States (up
from 230 million in 2001), which translates to 89 guns for every 100 people (Small
Arms Survey, 2007). Yemen has the second highest rate of gun ownership with 55
guns per 100 people, followed by Switzerlandwhich requires military serviceat
46 guns per 100 people, or approximately half the gun ownership rate of the US.
More guns, however, doesn’t necessarily translate into more gun owners. According
to General Social Survey data, three-quarters of people with guns own two or more
and about 3 percent of households own half of all the guns in America. The
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
prevalence of gun ownership has declined steadily in the past few decades. In 2010,
for example, one in five Americans owned a gun compared to one in three in 1980.
Today, guns are owned by about 30 percent of the American population. Men are
far more likely to own guns than women are. Legal gun ownership is higher among
whites than among blacks, higher in rural areas than in urban areas, and higher
among older people than among younger people.
Gun ownership numbers are based on public opinion surveys, gun
registration records, and expert testimony; hence the reliability of numbers can
vary widely from country to country. The Small Arms Survey (2007) gives high and
low estimates in addition to the averages presented above. According to Bureau of
Alcohol, Tobacco, Firearms and Explosives data, American gun manufacturing
increased 64 percent from 3.7 million in 2007 to 6.1 million in 2011 and gun sales
typically go up in the aftermath of a mass shooting. Background-checks increased
from 11 million in 2007 to 16.8 million in 2012. But background checks are not an
indication of sales because they’re not always required (e.g., for personal sales at
gun shows in some states) and one purchaser can buy more than one firearm.
Among law-abiding citizens, sport and self-defense are primary motives for
gun ownership, although the actual frequency of self-defense incidents is unknown
and available evidence that self-defense deters gun crime or reduces harm to victims
is ambiguous (NRC, 2005). The concept of self-defense particularly resonates with
women, who are often sold guns under the pretense that they are the “great
equalizer” with male strength. However, the risks of a gun in the home typically far
outweigh the benefits (Hemenway, 2011).
By contrast, criminals use guns for protection, to expedite the commission
of an offense (e.g., scare or kill the victim), escape, or a combination thereof
(Wright & Rossi, 1985). Thankfully the symbolism of firearms typically exceeds their
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
frequency of use. A gun is a ranged weapon that can project violence even when
unusedshowing the ‘bulge’ is often enough to gain the respect of rivals, while in
robberies, brandishing a weapon typically suffices because people do not wait for
proof that it works (Hemenway & Azrael, 2000). Most felons who use a gun during
an offense, however, claim no prior intent to fire a gun, suggesting the presence of
a gun alone greatly increases the chances of using it (Wright & Rossi, 1985). In other
words, when guns are around, pushing and shoving quickly escalate into shooting.
Moreover, adolescents substantially overestimate the percentage of their peers
who carry guns thus are more likely to carry for “protection” against other
adolescents supposedly carrying guns (Hemenway et al., 2011).
Policing Gun Violence
There is some truth to the adage, “Guns don’t kill people; people kill people.
The mere presence of guns, however, underlies tensions between law enforcement
and the community. Since the 1960s, social-psychologists have documented a
“weapons effect,” whereby having a weapon on hand increases aggression in people,
particularly people already aroused (Berkowitz, & LePage, 1967; Carlson, Marcus-
Newhall, & Miller, 1990); which is expected when police are on the scene. Research
even shows that drivers with guns in their cars are more likely to drive
aggressivelysomething to consider during a routine traffic stop (Hemenway,
Vriniotis, & Miller, 2006). Police in America are conditioned to expect firearms at
every turn; which of course is true because police are themselves armed. But this
assumed presence of guns makes it far harder for officers to retreat once they have
engaged and creates an implicit or explicit barrier to enactment of Sir Robert Peel’s
foundational principle of “policing by consent”the notion that law enforcement
owes its primary duty to the public, rather than to the state. It explains in part why
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
British citizens, who are generally unarmed, are around 100 times less likely to be
shot by a police officer, who too are unarmed, than Americans.
According to the National Law Enforcement Officers Memorial Fund, the
number of police officers shot and killed in the line of duty went up 56% from 41
in 2015 to 64 in 2016. This translates to about 0.007 percent of all police officers.
Twenty-one officers were killed in ambush-style shootings in 2016, including eight
who died in two assaults in 10 days in July 2016, in Dallas, Texas and Baton Rouge,
Louisiana. Both assaults occurred in the context of protests against police killings
of African-Americans. Ironically, the likelihood of a police officer being shot dead is
far higher than that of a member of the public being killed by the police. While there
is no centralized tracking system (The Washington Post and Guardian newspapers are
leading sources of information), an estimated 1,000 people per year are shot dead
by police, or 0.00003 percent of the general population. However, blacks are being
shot at a rate that is 2.5 times higher than whites, with 0.0005 percent of the black
population shot dead by police in 2016.
For every black male killed by a (white) police officer there are hundreds
more killed by other black males. Violent crime is largely intra-racial for all groups,
but the rate of black-on-black gun homicide has led some commentators to argue,
“Some Black Lives Don’t Matter” (Lowry, 2015). Centers for Disease Control and
Prevention data show blacks routinely constitute 5060 percent of shooting
homicide victims, despite constituting only 13 percent of the general US population.
A young black man is about five times more likely to be killed by a gun than a young
white man. And these numbers, dramatic as they are, understate the problem
because most gun deaths are ruled accidental or the result of suicide, but in 82
percent of cases where a black person is killed by a gun, it is judged a homicide.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
Gun Deaths in America
In 2014, there were 33,594 firearm deaths in the United States, a number
comparable to both motor vehicle traffic deaths and opioid deaths. Politicians often
talk about an opioid “crisis” or “epidemic” in America and by that logic, gun violence
should qualify for equal treatment. More than 90 Americans a day die by gunfire. It
breaks down to 21,386 suicides, 11,008 homicides, and 1,200 accidental deaths or
other. Americans are 10 times more likely to be killed by guns than people in other
high-income OECD countries (Grinshteyn & Hemenway, 2016). The rate of gun
violence in the United States is not the highest in the worldapproximately 30
counties in Central America, Africa, and the Middle East, rank much higher.
However, those countries with high levels of gun violence (e.g., El Salvador, The
Philippines, Iraq) are not like the United States in terms of G.D.P., life expectancy,
and education. For this reason, America’s rate of gun homicides (3.5 per 100,000
people) is an outlier.
More Guns, More Gun Violence?
Guns and homicides are statistically associated. Areas with a higher
prevalence of guns have a higher prevalence of gun homicides. The question is
whether the relationship is causal or not. We simply don’t know because of a lack
of robust data (Foran, 2016). The Centers for Disease Control and Prevention is
essentially prohibited from studying the public health effects of guns, for example,
even since NRA lobbyists convinced Congress to cut into its funding (retribution
for a series of studies in the mid-1990s perceived by the NRA as advocating for gun
According to the United Nations Office on Drugs and Crime (2010), the
firearms homicide rate, and homicide rate overall, is higher in the US than other
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
advanced countries (e.g., Australia, Canada, and those in Europe). But country-to-
country comparisons are difficult and often provide contradictory evidence. For
instance, Latin American countries with high levels of firearm homicide show low
levels of gun ownership. Honduras has a gun ownership rate of 6.2 per 100 people
and a gun homicide rate of 68.43 per 100,000 people. Colombia has a gun rate of
5.9 per 100 people and firearm homicide rate of 27.09 per 100,000.
Gun violence is not evenly distributed across America, with Southern regions
having a higher risk of both gun suicide and gun homicide (Parsons & Weigend,
2016). Using a validated proxy for firearm ownership, Miller et al. (2002) analyzed
the relationship between firearm availability and homicide across 50 states over a
ten-year period (198897). After controlling for poverty and urbanization, for every
age group, people in states with many guns have elevated rates of homicide,
particularly firearm homicide. The FBI’s Uniform Crime Report shows that
California had the highest number of gun murders in 20121,790, which is 68
percent of all murders that year and equivalent to 3.25 per 100,000 people in the
state. If you examine the per capita gun murder rate, however, District of Columbia
comes out top, with 12 gun murders per 100,000 people; followed by Louisiana
(10.16 per 100,000) and Mississippi (7.46 per 100,000).
Gun violence concentrates not just spatially but also socially. Gun violence
victims and offenders tend to be criminally active and generally know one another.
One study of a high-crime Boston community, for instance, found that 85 percent
of all fatal and nonfatal gunshot injuries occurred in a single social network of people
with criminal records that comprised less than 5 percent of the community’s total
population (Papachristos, Braga, & Hureau, 2012). Another study found that 70
percent of all nonfatal shootings in the entire city of Chicago occurred in a co-
offending network composed of less than 6 percent of the city’s population
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
(Papachristos, Wildeman, & Roberto, 2015). In Chicago, just being in network with
another gunshot victim increased an individual’s probability of victimization by 900
percent (Papachristos et al., 2015). Many in network people are gang members.
National figures from large cities indicate that while gang members comprise less
than one percent of the general population, over 20 percent of homicides in large
cities are gang related (Pyrooz, 2012). This is explained by the cyclical, reciprocal,
and retaliatory nature of gang violence (Decker, 1996). Hence why gang
membership “strongly and significantly increases the likelihood of carrying a gun”
(Thornberry et al., 2003, p. 131).
Gangs aside, how do we explain American exceptionalism among advanced
nations? Eric Monkkonen (2006) blames the legacy of mobility (which breaks social
ties), Federalism (a weak form of government), slavery (which rationalized a culture
of violence among white Southerners, where the murder rate is disproportionately
high), and tolerance (particularly with regard racial murders and killings by jealous
spouses). Given the crime rate correlates, inversely, with public faith in government
and trust in elected officials, Gary LaFree (1998) blames the decline of social
institutions in America. Essentially, if people feel society is unfair they are less
inclined to play by the rules (see also, Roth, 2009). Mark Kleiman (2009) blames the
severity of punishments in America (e.g., state execution, three strikes laws), which
contrary to popular belief do little to deter crime. Cesare Beccaria (1963) was in
fact the first to argue punishments, to be effective, must be swift and certain but
not necessarily severe, noting: “The countries and times most notorious for
severity of punishment have always been those in which the bloodiest and most
inhumane of deeds were committed” (p. 42).
To account for higher rates of gun violence in southern states, Richard
Nisbett and Dov Cohen (1996) identify a “culture of honor” in which southern
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
residents place an extraordinary value on personal reputation, family, and property
and frequently see violence as a way to solve personal problems. To account for
high rates of gun violence among the urban poor, scholars describe “subcultures of
violence” (i.e., gangs) in which the norms, values, and attitudes of its members
legitimize the use of violence to resolve conflicts (Wolfgang & Ferracuti, 1967), and
“honor subcultures” in which young men without legitimate means to earn respect
become hypersensitive to insult and rush to defend their reputation in dominance
contests (Gilligan, 1997). The disproportionate involvement of men as both victims
and perpetrators of gun violence may also reflect notions of “hegemonic
masculinity” (Messerschmidt, 1993).
The above are all interesting theories but it is difficult to draw causal
inferences. There’s also a chicken-and-egg question when it comes to gun violence
in America. On the one hand, rising crime leads to a perception of increased threat
and, therefore, an increase in the prevalence of gun ownership. On the other hand,
making firearms more available is followed by an increase in gun crime. Likewise,
the states with the strongest gun laws typically see the lowest gun death rates. But
it’s also easier to pass gun control laws in areas with low gun ownership, and harder
to pass them in areas with more gun owners.
Is Gun Violence Increasing?
In the short term, yes. The national gun homicide rate is rising at its fastest
pace since the early 1970s. However, gun homicide trends in a few big cities are
responsible for this rise. Chicago, the nation’s third-biggest city, for example,
accounts for about 20 percent of the year-on-year increase nationwide.
In the long term, however, the answer is no (see Pinker, 2011). Centers for
Disease Control and Prevention data show that gun homicides are down from
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
12,791 in 2006 to 11,008 in 2014. Gun homicides are down even as the nation’s
population grows. The gun homicide rate in 2014 was the lowest since CDC
records began in 1981. However, there are still about 30 gun homicides per day in
the United States and the gun homicide rate remains about eight times higher than
the rate in neighboring Canada, 18 times higher than in the United Kingdom, and
20-30 times higher than in Scandinavian Europe (Grinshteyn & Hemenway, 2016, p.
CDC data are derived from the National Vital Statistics System, which
collects death certificates that every state must file. The CDC offer a more accurate
measure of gun murders than the FBI’s Uniform Crime Report, which relies on
voluntary reporting of law enforcement agencies. By comparison, FBI data show
10,177 gun murders in 2006 and 9,616 in 2015about 26 per day. Given there
were 13,455 murders total in 2015, firearms were implicated in 71 percent of them.
CDC data includes 400 or so “justifiable homicides” including the use of
deadly force by a law enforcement officer, which are not murders. Either way, the
number of gun murders is down from all-time highs in the early 1990s. The number
of violent gun crimes (e.g., aggravated assaults or robberies committed with guns)
is also down. But the number of reported gun injuries is rising. There were 55,544
non-fatal injuries in 2011 resulting from assaults involving gunsup from 44,466 in
2009, according to CDC data. It appears improvements in modern medicine
emergency response, trauma surgery, antibiotics, and wound careresult in people
surviving today from injuries that 20 years ago would have killed them.
Nevertheless, stab wounds are typically less likely to kill the victim than gunshot
wounds, in part because of reduced hydrostatic shock to internal organs (Adelson,
1974). Hence why the case-fatality rate for suicide attempts with guns is higher than
other methods, including drug overdoses, cutting, and piercing (Miller et al., 2004).
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
More Guns, More Gun Accidents and Suicides?
Across states, both firearm prevalence and unsafe storage practices (i.e.,
storing firearms loaded and unlocked) are associated with higher rates of
unintentional firearm deaths (Miller et al., 2005). The majority of people killed in
firearm accidents are under age 24, and the shooter is typically a friend or family
member, often an older brother (Hemenway et al., 2010). According to a database
of accidental child-involved shootings maintained by Everytown, a gun violence
prevention group, at least 50 people per year get shot by a child under the age of
four. In many of these cases, a toddler finds a gun and accidentally shoots him- or
herself with it. However, there is one object parents should fear a hundred times
more than the gun in the house but don’t and that is a swimming pool. If a child
spends a day at a house that has both a gun and a swimming pool, the likelihood
the child dies is a hundred times greater from the swimming pool than it is from
the gun (Levitt & Dubner, 2005).
Beyond accidents, more than 60 percent of gun deaths are suicides. Given
that most suicides are impulsive, access to firearms becomes an important factor
in suicide prevention. Availability of firearms certainly determines whether suicide
attempts prove fatal (Miller, 2012). Gun availability is also a risk factor for youth
suicide in the United States, but the evidence gun availability increases adult suicide
rates is less compelling. Most of the disaggregate findings of particular studies (e.g.,
handguns are more of a risk factor than long guns, guns stored unlocked pose a
greater risk than guns stored locked) are suggestive but not yet well established
(Miller & Hemenway, 1999, 2001). Adolescents who commit suicide with a gun
typically use the family gun (Johnson et al., 2010). Perhaps reflecting over-
confidence, gun training is counter-intuitively associated with an increased likelihood
of storing firearms guns loaded and unlocked (Hemenway et al., 1995).
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
More Guns, Less Crime?
In the words of National Rifle Association CEO and Executive Vice President
Wayne LaPierre: “The best way to stop a bad guy with a gun is a good guy with a
gun” (as cited in Lichblau & Rich, 2012). The NRA’s position is gun availability deters
potential criminals. Critics argue more concealed guns equal more disputes
resolved with guns, which results in more violent crime. Who is correct?
Four generic types of “concealed carry” laws currently exist: (a) concealed
carry prohibited; (b) “may issue” (police have some discretion over who receives a
permit); (c) “shall issue” (police must provide a permit to anyone who is not
expressly prohibited by statue, as in Minnesota); and (d) unrestricted. According to
economist John Lott (2010), “Allowing citizens to carry concealed handguns
reduces violent crimes, and the reductions coincide very closely with the number
of concealed-handgun permits issued” (p. 20). Lott contends, “When state
concealed-handgun laws went into effect in a county, murders fell by about 8
percent, rapes fell by 5 percent, and aggravated assaults fell by 7 percent” (p. 59).
Colleague David Mustard (2001) also found, “allowing law abiding citizens to carry
concealed weapons does not endanger the lives of [police] officers and may help
reduce their risk of being killed” (p. 635).
Gun rights advocates often champion Lott and Mustard’s (1997) work but
their findings are strongly disputed. The National Research Council (2005), for
example, criticized the short time series, small number of jurisdictions, and
sensitivity of the data, arguing it was “impossible to draw strong conclusions from
the existing literature on the causal impact of these laws” (p. 121). For instance,
crime is down dramatically even in states that have not passed concealed-carry
laws. To prove causation would require researchers to discern what would have
happened if not for the law, which is almost impossible to model. One of the 17-
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
member committee (the late James Q. Wilson of “broken windows” fame),
however, wrote a dissenting opinion arguing the panel treated the Lott-Mustard
studies too harshly (NRC, 2005, Appendix A).
Ian Ayres and John Donohue (2003) are perhaps Lott and Mustard’s greatest
detractors. Based on an additional five years of county data, seven years of state
data, and tests in 14 more jurisdictions, they concluded that while shall-issue laws
did not increase violence, “the statistical evidence that these laws have reduced
crime is limited, sporadic, and extraordinarily fragile” (p. 1201). In a later study,
Ayres and Donohue (2009) argue, “the one consistent finding … is that right to
carry laws increase aggravated assault” (p. 229). A literature review on firearm
availability and homicide likewise concluded, “changes have neither been highly
beneficial nor highly detrimental” (Hepburn & Hemenway, 2008). There are two
explanations why: (a) Only a tiny percentage of the population seeks to obtain a
concealed weapon permit; and (b) those who do tend to be old, affluent, rural,
white males, who are at relatively low risk for either crime perpetration or
About a third of American public schools already have armed security.
Armed teachers are a logical extension of the growing “homeroom security”
movement: metal detectors, random searches, drug-sniffing dogs, radio frequency
monitors, surveillance cameras, private security, “school resource officers”
(Kupchik, 2010). There is no clear evidence that such measures make public schools
safer. Some studies have found a decrease in violence in schools with in-house
police officers, while others have found no relationship at all. Based on fieldwork
conducted in New York City public schools, Kupchik (2010) finds “the presence of
police in schools is unlikely to prevent another school schooling and the potential
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
for oppression of studentsespecially poor and racial/ethnic minority youthis a
more realistic and common threat than Columbine” (p. 82).
Law enforcement can’t do much to prevent a school shooting, although they
can, in a few instances, reduce its severity. But many people in life-or-death
situations freeze or shut down entirely. It takes months if not years to learn to
circumvent the confrontational tension and fear police officers experience in a
gunfight, say firearms instructors (see Ripley, 2013). In other words, teachers are
ill-prepared to take down body-armor wearing bad guys. The chances that an armed
officer or educator will shoot a child by accident are high. The chances of arriving
officers’ mistakenly shooting a teacher because he or she is seen with a weapon in
the aftermath of a shooting incident are higher.
Public safety departments have developed a number of techniques for
communicating and responding to critical incidents on school and college campuses
including mass notifications systems, firearm bands, and developing working
relationships with local law enforcement (Schafer, et al., 2010). One controversial
strategy is to go beyond training and preparing public safety personnel, and actually
train students to respond to an active shooter. This can be accomplished through
live action trainings, some which include using students as actors, even using
pretend gun shots and fake blood (Fox & Savage, 2009). One recent randomized
study examined student responses to a live shooter training video, finding that
students who watched the video felt more prepared, but also more afraid that a
shooting would take place (Peterson, et al., 2015). When weighing the costs and
benefits of these approaches, it is important to consider that the odds of a student
being killed at school are about 1 in 3 million, lower than the odds of being struck
by lightning. Schools are safer now than they have been in 20 years (Ripley, 2013).
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
How Do Criminals Get Guns?
Purchases from Federal Firearms Licensees account for only about 60
percent of gun sales. The 1994 Brady Handgun Violence Prevention Act mandates
background investigations (via the National Instant Criminal Background Check
System maintained by the FBI) and prohibits retail sales of guns to juveniles,
convicted felons, fugitives, illegal aliens, drug users, former mental patients, and
dishonorably discharged veterans. Under the common-law concept of “negligent
entrustment,” moreover, a gun cannot be sold to a person if the seller knows, or
reasonably should know, that the buyer poses an unusually high risk of misusing it.
But a privately-owned gun can be transferred legally in ways that bypass
Federal Firearms Licensees. The issue, therefore, is the 40 percent of gun
transactions that occur in the “secondary market” (Cook & Ludwig, 2000), where
federal law does not require transaction records or criminal background checks of
prospective gun buyers (NRC, 2005). The secondary market includes gun brokers
who a) sell guns directly; b) find customers for gun dealers who sell off the books;
and c) match sellers with gun buyers in gun shows (which include both licensed and
unlicensed gun dealers).
On the streets, everybody knows somebody from whom they can beg,
borrow or steal a gun. But the good news is it costs more and takes longer to get
guns in the underground market compared to the legitimate market, which suggests
gun regulations do make a difference (Cook, Ludwig, Venkatesh & Braga, 2007).
Still, thousands of guns stolen from manufacturers, importers, distributors, licensed
dealers, and private citizens each year make their way into the hands of prohibited
persons (Cook & Ludwig, 2000). Prohibited persons also acquire firearms from
licensees without theft via straw purchases (i.e., when the actual buyer uses another
person to complete the purchase and fill out the paperwork), “lying and buying”
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
(i.e., showing false identification and lying about their status), or buying from a
dealer knowingly involved and willing to disguise the illegal transaction by falsifying
the record of sale or reporting the gun as stolen (Braga et al., 2002). Corrupt
Federal Firearms Licensees account for less than 10 percent of gun trafficking
investigations conducted by the ATF but more than half of all guns diverted to
prohibited users (NRC, 2005).
Mental Illness and Gun Violence
The current focus on policies limiting gun sales to individuals with a
psychiatric history results from a clear link in the public’s mind between serious
mental illnesses and dangerousness (Thoits & Link, 2014; Link, Phelan, Bresnahan,
Stueve, & Pescosolido, 1999). The belief that mental illness causes unpredictable
violence is pervasive (Markowitz, 2010), and this perception has been particularly
perpetuated by the media coverage of mass shootings. However, the vast majority
of people with mental illness are not violent. In fact, large studies have found that
people with mental illness are actually less likely to be violent that similar individuals
without mental illness (Monahan, et al. 2001), and people with serious mental illness
are more likely to be victims of violence than perpetrators (Hughes et al., 2012).
Creating laws focused on individual with mental illness may perpetuate the stigma
surrounding mental illness (Beck, 2016) and impact whether or not someone seeks
needed treatment. Moreover, individuals with mental illness are often undiagnosed,
meaning there is no record of their illness that could be reviewed prior to
purchasing a gun.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
Gun Laws in Minnesota
In Minnesota, a permit to purchase is required to transfer/purchase “military-
style assault weapons” and handguns through Federal Firearms License dealers
(Minnesota Statutes § 624.7131). A permit to carry also acts as a permit to purchase
for Minnesota residents. Traditional rifles and shotguns (primarily used in hunting)
may be purchased without a permit, but Minnesota is a “shall issue” state, meaning
a permit to carry a pistol is required to carry handguns. Minnesota Statutes §
624.714 observe “a person, other than a peace officer…who carries, holds, or
possesses a pistol in a motor vehicle, snowmobile, or boat, or on or about the
person's clothes or the person, or otherwise in possession or control in a public
place without first having obtained a permit to carry the pistol is guilty of a gross
misdemeanor.” Concealment is permitted but not required, and only handguns may
be carried concealed. To obtain a permit to carry, people must first complete
authorized firearms training.
Source: Bumgarner, Hilal, & Densley (2016).
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
Part II: Making Sense of Senseless Mass Shootings
Is Mass Shooting Increasing?
Grant Duwe (2007), director of research and evaluation at the Minnesota
Department of Corrections, used FBI Supplementary Homicide Reports and The
New York Times to identify 116 mass public shootings in the United States during
the Twentieth Century; over half of which took place after 1980 (Duwe, 2007). It
is important to note these are raw figures; the US had far fewer people 50 or 100
years ago. Guns killed an average of 4.92 victims per mass murder, marginally more
than knives, blunt objects, and bare hands at 4.52 people per incident, but
significantly less than explosives at 20.32 people (Duwe, 2007). Assault weapons
were used in only 4 percent of mass shootings, but they do result in more wounded
victims (Duwe, 2007).
Mass shootings are rarebut focusingevents (Fleming et al., 2016;
Harding, Fox, & Mehta, 2002). How rare depends upon how mass shooting is
defined. The FBI’s tracks active shooter incidents,” of which there were 160
between 2000 and 2013, but not all of them resulted in mass casualties (Blair &
Schweit, 2014). Some analysts count mass shootings in which multiple people are
shot but survive. Others exclude events involving family members. These subtle
differences result in conflicting accounts of the nature and extent of mass shooting.
According to UCR data, however, there have been about 20 mass shootings every
year since the 1970s (Fox & DeLateur, 2014). At this rate, people killed in mass
shootings make up less than half of one percent of the people shot to death in the
United States each year. Further, the trend is flat. “There has been no increase in
mass shootings and certainly no epidemic” (Fox & DeLateur, 2014, p. 130).
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
Duwe (2007) defined a mass public shooting as an incident in which four or
more victims were killed publicly with guns within 24 hoursin the workplace,
schools, restaurants and other public placesexcluding shootings in connection
with crimes such as robbery, drugs, or gangs.
In collaboration with Mother Jones and The Washington Post, Duwe has
developed a database of 131 events in which four or more people were killed by a
lone shooter (or two shooters in three cases) since 1966when a sniper murdered
his wife and mother, then killed 14 others from atop a 27-story tower at the
University of Texas. These data show an average of eight people died during each
mass shooting event, often including the shooters. Perpetrators generally commit
suicide after their attacks, either themselves or by provoking law enforcement to
shoot them (known as “suicide by cop”). All but three of the mass shooters were
male. The youngest was 11 years of age, the oldest was 66. The average age was
mid-30s. 2012 was the second worst year for public shootings, seven, behind 1991
when eight incidents took place.
The frequency of mass public shootings has not increased in recent years,
but they have become deadlier. The 2017 Las Vegas attack, with 58 confirmed dead,
was the worst in recent US history and possibility the first to use a fully-automatic
weapon. The next three shootings with the highest number of casualties all
happened within the past 10 yearsthe 2016 Orlando nightclub shooting (49 dead),
Virginia Tech in 2007 (32 dead), and Sandy Hook in 2012 (27 dead). Compared to
public mass shooters in other countries, those in the United States are more likely
to arm themselves with multiple weapons and attack at school and workplace
settings, while offenders from other countries are more likely to strike at military
sites (Lankford, 2015).
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
Owing to the severity and placement of some public mass shootings, people
often ask why such events are not classified as acts of terrorism. The State
Department defines terrorism as “premeditated, politically motivated violence
perpetrated against non-combatant targets by subnational groups or clandestine
agents.” By this definition, some shootings meet the criteria, such as the racially-
motivated massacre in 2015 of nine black worshippers in South Carolina by a self-
avowed white supremacist. When mass shootings are labeled terrorism, the public
and political response is typically very different (DeFoster, 2017).
In Progress: The Mass Violence Project
The Violence Project is currently working on building a database of mass shooters,
extending the work done by Grant Duwe, Mother Jones, and The Washington Post,
by coding shooters on 50 different psycho-social variables. We aim to use statistical
modeling to look for patterns in the data that can better inform research and policy.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
Deadliest American Mass Shootings Ranked by Body Count
0 10 20 30 40 50 60 70
Las Vegas, NV. Oct. 1, 2017
Orlando, FL. Jun. 12, 2016
Virginia Tech, VA. Apr. 16, 2007
Newtown, CT. Dec. 14, 2012
Killeen, TX. Oct. 16, 1991
San Ysidro, CA. Jul. 18, 1984
Austin, TX. Aug. 1, 1966
San Bernardino, CA. Dec. 2, 2015
Edmond, OK. Aug. 20, 1986
Fort Hood, TX. Nov. 5, 2009
Binghamton, NY. Apr. 3, 2009
Littleton, CO. Apr. 20, 1999
Seattle, WA. Feb. 18, 1983
Wilkes-Barre, PA. Sep. 25, 1982
Camden, NJ. Sep. 5, 1949
Washington DC. Sep. 16, 2013
Aurora, CO. Jul. 12, 2012
Atlanta, GA. Jul. 29, 1999
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
Why Do Mass Shooters Shoot?
Among the biological factors implicated in mass shootings are significant brain
pathology, XYY chromosome, blood levels of neurotransmitters, and types and
levels of hormones. Psychological factors include psychoses, dissociative disorders,
suicidality, personality disorders, and psychopathy. Among more sociologically
inclined theories are those relating to strain, aggression, adverse childhood
experiences (e.g., abuse, having a mentally ill parent, domestic violence against a
parent, a household member in prison, divorced parents, or a household member
with a drug or alcohol problem), neutralization, labeling, and self or social control
(for a review, see Riedel & Welsh, 2015).
Fox and Levin (2012) propose a “motivational typology” of mass shooters
that includes the incentives of power, revenge, loyalty, profit, and terror. Fox and
DeLateur (2014, p. 126) observe, mass murder rarely involves a sudden explosion
of rage. To the contrary, mass killers typically plan their assaults for days, weeks,
or months.” For example, the fact that the 1999 Columbine High School massacre
landed on Adolf Hitler’s birthday was no coincidence. This has led some to study
the “routine activities” of mass shooters (Hilal, Densley, Li, & Ma, 2014) or examine
“warning behaviors” and “leakage” (i.e., communication of intent to a third party)
in the context of threat assessment (Meloy & O’Toole, 2011; O’Toole, 2000). The
vast majority of mass shooters signal their intentions in advance, though usually not
directly to their intended targets.
Studies have found mass shootings may be socially contagious (Towers et al.,
2015) or that copycat effects exist (Follman, 2015; Lankford & Tomek, 2017). So-
called “fame-seeking” public mass shooters appear more common in recent
decades and tend to be significantly younger and more likely to kill and wound more
victims than other offenders (Lankford, 2016).
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
Social media may also play an important role in exacerbating mass violence
(Peterson & Densley, 2017a). “Performance violence” is violence enacted for the
purpose of engaging an audience. Perpetrators of mass violence are often
celebrated in public, which feeds offenders’ delusions of grandeur” (Lankford,
2016) and potentially encourages additional violent performances to gain notoriety.
For this reason, researchers (including the first author; see Ziv, 2017) have called
on mainstream media to stop publishing the names and photographs of mass killers
(for a discussion see, Lankford, & Madfis, 2017). Still, social media cannot be so
easily controlled. Mass shootings always go viral and bring the perpetrator a status
in death that they did not have in life; hence why the 2016 Pulse Nightclub shooter
checked his Facebook account during his massacre (Peterson & Densley, 2017b).
But ex post facto explanations and an excess of false positives are two major
problems with explanations of mass shooters. Case in point: since psychologist
Albert Bandura (1977) first argued media in general, and television in particular,
provide a power source of models for aggressive conduct, a large number of studies
have shown how popular culture teaches aggressive and violent behavior (Murray,
2008). But violent media merely acts as a “facilitator” for people already prone to
violence. As Peter Langman (2009), in his study of school shooters, explains: “These
are not ordinary kids who played too many video games. … These are simply not
ordinary kids”.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
The Performance of Violence
An electronically-mediated world gives new meaning to William Shakespeare’s
observation that, “All the world’s a stage, and all the men and women merely
players.Criminologist Ray Surette (2015) observes that violent performers in
the age of social media are both willing and unwilling. The willing are those who
“produce” violent content for consumption. They are fully aware of their lead or
supporting role in violent performances, typically as perpetrators. They
sometimes record or film violence themselves and at least tacitly support the
distribution of violent content.
The unwilling, by contrast, play a lead or supporting role without informed
consent. They are typically the victims of violence, “recorded in a production
similar to a nature documentary,” Surette explains. The unwilling are people
filmed in secret or in captivity. People who are repeatedly victimized every time
their initial victimization is replayed or repurposed.
Finally, there is the audience. Performers are oriented both to each other
and to an audience “out there.” Why do we watch these violent performances?
For the very same reason why we cannot look away from a car crash. A perfectly
normal combination of sadomasochismthe desire to think about or imagine
hurting or being hurtand an interest in what is hidden and secret, known as
exhibitionism and voyeurism. Some enjoy the performance of violence. They find
it thrilling, like a horror movie. Most are saddened by it, particularly if they
identify with the victims as if they were themselves or their loved ones. Forced to
watch unedited, unpredictable, and sometimes disturbing violent performances
again and again, others experience the trauma that causes post-traumatic stress
disorder vicariously.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
Part III: Looking for Solutions
What Can Be Done About Gun Violence?
In the wake of the December 2012 Newtown shooting, which left 20 children
and six teachers dead, President Barack Obama unveiled the most sweeping gun
control proposals in a generation, including: a ban on new purchases of “military-
style” assault weapons; a ban on the sale of high-capacity (more than 10 rounds)
ammunition clips; a ban on possession and sale of armor-piercing bullets;
background checks on all gun sales (including private purchases and transactions at
gun showsclosing the “gun show loophole”); harsher penalties for gun-traffickers,
especially unlicensed dealers who buy arms for criminals; and a new chief of the
federal Bureau of Alcohol, Tobacco, Firearms and Explosives. Many of these
“solutions” are still on the table. The question is, will they work?
Regulating Gun Dealers
In 2000, ATF conducted focused compliance inspections on dealers who had
been uncooperative in response to trace requests and on Federal Firearms
Licensees who had ten or more gun crimes traced to them the prior year. These
selective inspections disclosed violations in about 75 percent of the 1,012 dealers
inspected (Riedel & Welsh, 2015). This is promising.
Reducing the Lethality of Guns
Evaluation evidence is lacking (NRC, 2005) but intuitively, designating certain
firearms as “dangerous”, restricting access to certain types of weapons or
ammunition by law, making weapons less dangerous by requiring trigger locks or
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
prohibiting modifications such as “bump fire stocks” that replaces a rifle’s standard
stock (the part held against the shoulder), thus enabling the weapon to slide back
and forth and fire at nearly the rate of a fully automatic firearm, should limit the
number of causalities in a single event.
Altering Gun Uses or Storage
New to the market are so-called “smart guns” that use biometrics and
technology (e.g., RFID chips, fingerprint recognition, magnetic rings) to prevent use
by unauthorized persons. Smart guns are intended to prevent accidental discharge
and/or use and misuse of firearms by children. Further, the technology should in
theory render lost and stolen guns impotent, thus curbing the secondary market,
and create a “personal statement” (as Q from the James Bond movie Skyfall
describes it) that will assist law enforcement investigations. However, smart guns
have been criticized on the grounds that biometrics take time to process and are
often inaccurate, which could result in failure at times when the gun is needed most.
As a new technology, there is little evaluation data available.
Limiting Gun Sales by State
To reduce straw purchases, some states have passed laws limiting the
number of guns that an individual may purchase during a specific time period (e.g.,
one every 30 days). No controlled studies have shown harm reduced due to this
interventionindeed it may simply compel straw purchasers to travel to another
nearby state or jurisdiction with less restrictive laws. If it is to work, therefore, it
must be enacted at federal level.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
Screening Gun Buyers
Very few applicants are currently refused. Jens Ludwig and Philip Cook (2000)
found no effects comparing 32 pre-Brady Act states with 19 (plus Washington DC)
Brady Act-compliant states. The only effect was a reduction in gun suicides for
people aged 55 or over.
Gun Buy-Back Programs
The assumptions underlying gun buy-backs are badly flawed. First, guns
typically recovered are the ones least likely to be used in criminal activities, including
many old or inoperative guns. Second, because replacement guns are so easily
obtained any decline in the number of guns on the street is likely to be smaller than
the number of guns turned in. Available evidence suggests gun buy-backs have no
effect on gun-related violence at all (NRC, 2005).
Banning Assault Rifles
It is illegal for private citizens to possess fully automatic firearms
manufactured after May 19, 1986 and ownership of earlier models requires a federal
license. However, the 1994 assault weapons ban grandfathered in assault weapons
and large-capacity magazines capable of holding more than ten rounds and was
ridden with loopholes that allowed manufacturers to rename their weapons and
make minor modifications on copycat models that could be sold legally. Perhaps for
this reason (and the short time period available for analysis) the empirical evaluation
revealed no clear impact on gun violence (NRC, 2005). Perhaps more importantly,
URC data show about 70 percent of all gun murders are committed with a handgun.
While banning high-capacity magazines would affect the number of bullets loaded
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
into a semi-automatic handgun, this (like an assault weapons ban) would have no
direct effect on the availability of murderers’ weapon of choicethe handgun.
What Works in Gun Violence Prevention and Intervention?
Kleiman (2011, pp. 186-7) observes, reducing the number of firearms in
private hands by 90 percent would no doubt reduce the homicide rate. But reducing
the number by 10 percent would only have a small effect on crime as opposed to
accident or suicide prevention. The experience with states passing “shall issue” laws
provides no evidence of substantial criminal violence by holders of those permits.
Thus, two of the major goals on gun control advocatesreducing the prevalence
of firearm ownership and preventing the passage of “shall issue” lawsare largely
irrelevant to the project of reducing victimization risk (Kleiman, 2011).
Kleiman (2011) clarifies, however, reducing criminals’ access to firearms can
reduce the level of criminal violence with firearms. As such, universal background
checks (e.g., private sellers must verify eligibility through a licensed gun dealer) and
limiting the number of firearms anyone other than a licensed dealer can purchase
over the course of a month would be a step in reducing access to guns by those
likely to use them criminally. Tracing guns used in crimes back to their most recent
legal sale can equally help identify problem gun dealers. Requiring guns to be fired
before sale and entering the ballistic signatures on the bullet and the cartridge
entered into a database along with the serial number of the weapon would extend
the capacity to trace guns used in the commission of a crime in which the bullet or
the cartridge is left at the crime scene but the gun itself is not recovered. The gun’s
last legal purchaser could then be asked to account for what happened to it.
Intensive, intelligence-led, police patrols directed against illicit gun carrying in
high-violence neighborhoods are the next step in dealing with the secondary
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
market. When homicide victims are found outdoors we can infer homicide
offenders are carrying guns in public. But if criminals know their chances of getting
caught red-handed are high, they will be forced to change their gun-carrying
behaviors. Such is the logic behind Group Violence Intervention (GVI), a well-
documented violence reduction strategy that began life as “Operation Ceasefire”
in Boston in the 1990s and now is codified by the National Network for Safe
Communities (2013).
There is “strong empirical evidence” for GVI’s effectiveness (Braga &
Weisburd, 2012, p. 25). GVI begins with a problem analysis, such as a systematic
review of all violent incidents and an audit or mapping of all violent groups in any
given jurisdiction. Once the key players are identified, coordinated law enforcement
action against the most violent group follows in an effort to demonstrate to other
groups that violence will not be tolerated. Next, community moral voices and social
service providers partner with law enforcement to engage directly with violent
group members (and through them, their associates) in a “call-in,” or face-to-face
meeting, at a venue of civic importance (Kennedy, 2011).
The call-in is perhaps the most famous GVI tactic, to the extent it is
commonly misrepresented as the entire strategy. At each call-in, group members
receive three direct, mutually reinforcing, messages. First, police and prosecutors
communicate that future violence in furtherance of the group will be met with swift,
severe, and certain consequences; in part because the entire group will be held
accountable for violence perpetrated by any one member. In other words, if one
group member violates the terms of the ceasefire, law enforcement will pull every
civil and criminal lever available (e.g., outstanding warrants, probation and parole
violations, open cases) to dismantle the entire group (Braga & Weisburd, 2012).
Second, community representatives articulate why violence is morally
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
reprehensible and henceforth unacceptable. In doing so, they clarify and reinforce
the community’s standards, aspirations, frustrations, and expectations, but also
reintegrate group members back into the community on the condition of
nonviolence. The strong presence of police and community working together,
heightens the perceived risk of apprehension and sanction (Braga & Weisburd,
2012, p. 349). Third, social service providers inform group members that genuine
help is available for those who want it, thus facilitating an honorable exit from street
life via counseling, employment, education, and training (National Network for Safe
Communities 2013).
Further, buy-and-bust operations or incentives for arrestees to provide
information about buyers and sellers in the illegal gun market may prove more
effective than similar efforts directed at the illegal drug market. That is because
guns, unlike drugs, are durable goods, which means market transactions are lower
and the risks of exchange are higher (Densley, 2013).
At the same time, we need to change attitudes toward gun carrying.
Criminals often procure guns from friends and family members. Just as we now
accept that friends don’t let friends drive drunk, we need a national public-health
campaign that instills the message that friends who supply or store guns for others
are equally culpable for the crimes committed with those guns (for more on guns
and public health, see Hemenway, 2004). While research on the deterrent effects
of sentencing enhancements for firearms is mixed (NRC, 2005), states could offer
substantial rewards for information leading to the arrest of people carrying or
possessing a gun illegally and institute a gun-emphasis policy in investigations and
prosecutions of violent crimes.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
Adelson, L. (1974). The pathology of homicide: A vade mecum for pathologist, prosecutor
and defense counsel. Springfield, IL: Charles C Thomas.
Ayres I. & Donahue, J. (2003). Shooting down the “more guns less crime”
hypothesis. Stanford Law Review, 55, 1193–1312.
Ayres I. & Donahue, J. (2009). More guns, less crime fails again: the latest evidence
from 1977-2006. Econ Journal Watch, 6, 218238.
Bandura, A. (1977). Social learning theory. New York: General Learning Press.
Beccaria, C. ([1764] 1963). On crimes and punishments. Indianapolis, IL: Bobbs-
Beck, J. (2016, Jun. 7). Untangling gun violence from mental illness. The Atlantic.
Retrieved from
Berkowitz, L. & LePage, A. (1967). Weapons as aggression-eliciting stimuli. Journal
of Personality and Social Psychology, 7, 202207.
Blackstone, W. (1765). Commentaries on the laws of England. Oxford: Clarendon
Blair, J. P. & Schweit, K. W. (2014). A Study of active shooter incidents, 20002013.
Washington DC: U.S. Department of Justice, Federal Bureau of Investigation.
Braga, A., Cook, P., Kennedy, D., & Moore, M. (2002). The illegal supply of firearms.
In M. Tonry (Ed.) Crime and Justice: A Review of Research, Vo. 29 (pp. 319-352).
Chicago, IL: University of Chicago Press.
Braga, A. & Weisburd, D. (2012). The effects of focused deterrence strategies on
crime: A systematic review and meta-analysis of the empirical evidence.
Journal of Research in Crime and Delinquency, 49, 323358.
Bumgarner, J., Hilal, S., & Densley, J. (2016). Minnesota’s criminal justice system.
Durham, NC: Carolina Academic Press.
Carlson, M., Marcus-Newhall, A., & Miller, N. (1990). Effects of situational
aggression cues: A quantitative review. Journal of Personality and Social
Psychology, 58, 622633.
Cook, P. & Ludwig, J. (2000). Gun violence: The real costs. New York: Oxford
University Press.
Cook, P., Ludwig, J., Venkatesh, S. & Braga, A. (2007). Underground gun markets.
The Economic Journal, 117, F558F588.
Decker, S. H. (1996). Collective and normative features of gang violence. Justice
Quarterly, 13, 243264.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
DeFoster, R. (2017). Terrorizing the masses: Identity, mass shootings, and the media
construction of terror. New York: Peter Lang.
Densley, J. (2013, Mar. 8). So, what will actually work to reduce gun violence?
MinnPost. Retrieved from
Densley, J. (2016, Jan. 5). Protest movements, guns and double standards in
America. Star Tribune. Retrieved from
Duwe, G. (2007). Mass murder in the United States: A history. Jefferson, NC:
McFarland & Company.
Fleming, A., Rutledge, P., Dixon, G., & Peralton, S. (2016). When the smoke clears:
focusing events, issue definition, strategic framing and the politics of gun
control. Social Science Quarterly, 97, 11441156.
Folman, M. (2015, Oct. 6). How the media inspires mass shooters. Mother Jones.
Retrieved from
Foran, C. (2016, Jan. 21). The missing data on gun violence. The Atlantic. Retrieved
Fox, J. & Levin, J. (2012). Extreme killing: Understanding serial and mass murder, 2nd ed.
Thousand Oaks, CA: Sage.
Fox, J. A. & DeLateur, M. (2014). Mass shootings in America: Moving beyond
Newtown. Homicide Studies, 18, 125145.
Fox, J.A. & Savage, A. (2009). Mass murder goes to college: An examination of
changes on college campus following Virginia Tech. American Behavioral
Scientist, 52, 1465-1485.
Gallup. (2016). Guns: Gallup historical trends. Retrieved from
Goss, K. (2006). Disarmed: The missing movement for gun control in America. Princeton,
NJ: Princeton University Press.
Grinshteyn, E. & Hemenway, d. (2016). Violent death rates: The US compared with
other high-income OECD Countries, 2010. The American Journal of Medicine,
129, 266273.
Gilligan, J. (1997). Violence: Reflections on a national epidemic. New York: Vintage
Harding, D., Fox, C., & Mehta, J. (2002). Studying rare events through qualitative
case studies: lessons from a study of rampage school shootings. Sociological
Methods Research, 31, 174217.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
Hemenway, D. (2004). Private guns, public health. Ann Arbor, MI: University of
Michigan Press.
Hemenway, D. (2011). Risks and benefits of a gun in the home. American Journal of
Lifestyle Medicine, 5, 502511.
Hemenway, D. & Azrael, D. (2000). The relative frequency of offensive and
defensive gun use: Results of a national survey. Violence and Victims, 15, 257
Hemenway, D, Barber, C. & Miller, M. (2010). Unintentional firearm deaths: a
comparison of other-inflicted and self-inflicted shootings. Accident Analysis &
Prevention, 42, 11848.
Hemenway, D. Solnick, S. & Azrael, D. (1995). Firearm training and storage. JAMA,
273, 4650.
Hemenway, D., Vriniotis, M., & Miller, M. (2006). Is an armed society a polite
society? Guns and road rage. Accident Analysis and Prevention, 38, 687695.
Hepburn, L. & Hemenway, D. (2004). Firearm availability and homicide: A review
of the literature. Aggression and Violent Behavior, 9, 41740.
Hilal, S., Densley, J., Li, S. & Ma, Y. (2014). The routine of mass murder in China.
Homicide Studies, 18, 83104.
Hughes, K., Bellis, M.A., Jones, L., Wood, S., Bates, G., et al. (2012). Prevalence and
risk of violence against adults with disabilities: A systematic review and meta-
analysis of observation studies. The Lancet, 379, 16211629.
Johnson, R, Barber, C., Azrael, D., Clark, D., Hemenway, D. (2010). Who are the
owners of firearms used in adolescent suicides? Suicide and Life Threatening
Behavior, 40, 609611.
Kennedy, D. (2011). Don’t shoot: One man, a street fellowship, and the end of violence
in inner-city America. New York: Bloomsbury.
Kessler, G. (2013, Jan. 11). Bill Clinton’s over-the-top ‘fact’ on mass shootings. The
Washington Post. Retrieved from:
Kelling, G. & Wilson, J. (1982). Broken windows: The police and neighborhood
safety. The Atlantic. Retrieved from:
Langman, P. (2009). Why kids kill: Inside the minds of school shooters. New York:
Palgrave Macmillan.
Lankford, A. (2016). Fame-seeking rampage shooters: initial findings and empirical
predictions. Aggression and Violent Behavior, 27(1), 122-129.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
Lankford, A. (2016). Are America's public mass shooters unique? A comparative
analysis of offenders in the united states and other countries. International
Journal of Comparative and Applied Criminal Justice, 40(2), 171-183.
Lankford, A., & E. Madfis. (2017). Don’t name them, don’t show them, but report
everything else: a pragmatic proposal for denying mass shooters the attention
they seek and deterring future offenders. American Behavioral Scientist, doi:
Lankford, A. & Tomek, S. (2017). Mass killings in the United States from 2006 to
2013: social contagion or random clusters? Suicide and LifeThreating Behavior.
Lapore, J. (2012, Apr. 23). Battleground America: one nation under the gun. The
New Yorker. Retrieved from
Levitt, S. & Dubner, S. (2005). Freakonomics: A rogue economist explores the hidden
side of everything. New York: William Morrow.
Lott, J. (2010). More guns, less crime: Understanding crime and gun control laws.
Chicago, IL: University of Chicago Press.
Lott J. & Mustard, D. (1997). Crime, deterrence, and right-to-carry concealed
handguns. Journal of Legal Studies, 26,168.
Lowry, R. (2015, May 27). #SomeBlackLivesDontMatter. Politico Magazine.
Retrieved from
Kleiman, M. (2009). When brute force fails: How to have less crime and less punishment.
Princeton, NJ: Princeton University Press.
Kupchik, A. (2010). Homeroom security: School discipline in an age of fear. New York:
NYU press.
LaFree, G. (1998). Losing legitimacy: Street crime and the decline of institutions in
America. Boulder, CO: Westview Perseus.
Lichblau, E. & Rich, R. (2012, Dec. 21). N.R.A. envisions ‘a good guy with a gun’ in
every school. New York Times. Retrieved from
Link, B. G., Phelan, J. C., Bresnahan, M., Stueve, A., & Pescosolido, B. A. (1999).
Public conceptions of mental illness: Labels, causes, dangerousness, and social
distance. American Journal of Public Health, 89, 1328-1333.
Ludwig, J. & Cook, P. (2000). Homicide and suicide rates associated with
implementation of the Brandy handgun violence prevention act. Journal of the
American Medical Association, 284, 585601.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
Markowitz, F. (2010). Mental illness, crime, and violence: Risk, context, and social
control. Aggression and Violent Behavior, 16, 36-44.
Meloy, J. R. & O’Toole, M. E. (2011). The concept of leakage in threat assessment.
Behavioral Sciences and the Law, 29, 513-527.
Messerschimdt, J. (1993). Masculinities and crime: critique and reconceptualization of
theory. Totowa, NJ: Rowman & Littlefield.
Miller, M. (2012). Preventing suicide by preventing lethal injury: the need to act on
what we already know. American Journal of Public Health, 102, 13.
Miller, M. & Hemenway, D (2001). Gun prevalence and the risk of suicide: A review.
Harvard Health Policy Review, 2, 2937.
Miller, M. & Hemenway, D. (1999). The relationship between firearms and suicide:
A review of the literature. Aggression and Violent Behavior: A Review Journal, 4,
Miller, M., Azrael, D. & Hemenway, D. (2002). Household firearm ownership levels
and homicide rates across U.S. regions and states, 1988-1997. American
Journal of Public Health, 92, 19881993.
Miller, M., Azrael, D., Hemenway, D. (2004). The epidemiology of case fatality rates
for suicide in the Northeast. Annals of Emergency Medicine, 72330.
Miller, M., Azrael, D., Hemenway, D. & Vriniotis, M. (2005) Firearm storage
practices and rates of unintentional firearm deaths in the United States.
Accident Analysis and Prevention, 37, 6667.
Monahan, J., Steadman, H. J., Silver, S., Appelbaum, P. S., Robbins, P. C., Mulvey, E.
P., Roth, L. H., Grisso, T., & Banks, S. (2001). Rethinking risk assessment: The
MacArthur study of mental illness and violence. New York: Oxford University
Monkkonen, E. (2006). Homicide: explaining Americas exceptionalism. American
Historical Review, 111, 7694.
Murray, J. (2008). Media violence: The effects are both real and strong. American
Behavioral Scientist, 51, 12121230.
Mustard, D. (2001). The impact of gun laws on police deaths. Journal of Law and
Economics, 44, 635658.
National Network for Safe Communities (2013). Group Violence Intervention: An
Implementation Guide. Washington, DC: U.S. Department of Justice, Office of
Community Oriented Policing Services.
National Research Council (NRC). (2005). Firearms and violence: A critical review.
Washington D.C.: The National Academies Press.
Nisbett, R., & Cohen, D. (1996). Culture of honor. Boulder, CO: Westview Press.
Oliphant, B. (2017). Bipartisan support for some gun proposals, stark partisan
divisions on many others. Pew Research Center. Retrieved from
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
O’Toole M. E. (2000). The school shooter: A threat assessment perspective. Quantico,
VA: Critical Incident Response Group, FBI Academy, National Center for the
Analysis of Violent Crime.
Papachristos, A.V., Braga, A. & Hureau, D. (2012). Social networks and the risk of
gunshot injury. Journal of Urban Health, 89, 9921003.
Papachristos, A.V., Wildeman, C., & Roberto, E. (2015). Tragic, but not random:
The social contagion of nonfatal gunshot injuries. Social Science & Medicine,
125, 139150.
Peterson, J.K., & Densley, J. (2017a). Cyber violence: What do we know and where
do we go from here? Aggression and Violent Behavior, 34, 193200.
Peterson, J.P., & Densley, J. (2017b). How social media sends extremism into
overdrive. CNN. Retrieved from
Peterson, J.K., Sackrison, E., & Polland, A. (2015). Preparing for possible shootings
on campus: The impact on students. Journal of Threat Assessment and
Management, 2, 127-138.
Pinker, S. (2011). The better angels of our nature: Why violence has declined. New York:
Pyrooz, D. (2012). Structural covariates of gang homicide in large US cities. Journal
of Research in Crime and Delinquency, online first.
Riedel, M. & Welsh, W. (2015). Criminal violence: Patterns, causes, and prevention (4th
ed.). New York: Oxford University Press.
Ripley, A. (2013, Jan. 16). Your brain in a shootout: Guns, fear and flawed Instincts.
Time. Retrieved from:
Roth, R. (2009). American homicide. Cambridge, MA: Harvard University Press.
Schafer, J., Heiple, E., Giblin, M., & Burruss, G. (2010). Critical incident preparedness
and response on post-secondary campuses. Journal of Criminal Justice, 38, 311-
Small Arms Survey (2007). Guns and the City. Cambridge: Cambridge University
Surette, R. (2015). Performance crime and justice. Current Issues in Criminal Justice,
27, 195216.
Sweeny, K. & Saul, C. (2013). All guns are not created equal. Chronicle of Higher
Education, February 1, B4-B5.
Thoits, P.A., & Link, B.G. (2015). Stigma resistance and well-being among people in
treatment for psychosis. Society and Mental Health, online first.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
Thornberry, T., Krohn, M., Lizotte, A., Smith, C. & Tobin, K. (2003). Gangs and
delinquency in developmental perspective. Cambridge: Cambridge University
Winkler, A. (2013). Gunfight: The battle over the right to bear arms in America. New
York: W. W. Norton.
Wolfgang M. & Ferracuti, F. (1967). The subculture of violence. London: Tavistock.
Wright, J. & Rossi, P. (1985). The armed criminal in America: A survey of incarcerated
felons. Washington D.C.: National Institute of Justice.
Ziv, S. (2017, Oct. 3). Mass killers like the Vegas shooter should not be named in
news coverage, experts say. Newsweek. Retrieved from
Data Sources
Bureau of Alcohol, Tobacco, Firearms and Explosives, Annual Firearms
Manufacturers and Export Report
Everytown for Gun Safety, #NotAnAccident Index
Federal Bureau of Investigation, Uniform Crime Reports
General Social Survey
Mother Jones, US Mass Shootings, 1982-2017
National Center for Injury Prevention and Control, Injury Mortality Reports
National Center for Injury Prevention and Control, Fatal Injury Reports
National Law Enforcement Officers Memorial Fund
United Nations Office on Drugs and Crime, UNODC Homicide Statistics
USA Today, Nation Behind the Bloodshed: Every U.S. Mass Killing Since 2006
The Washington Post, The Math of Mass Shootings
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
Want to Learn More?
Americans for Responsible Solutions
Brady Campaign to Prevent Gun Violence
Coalition to Stop Gun Violence
Everytown for Gun Safety
Harvard Injury Control Research Center
National Network for Safe Communities
Joyce Foundation
Law Center to Prevent Gun Violence
National Rifle Association
Protect Minnesota
University of Chicago Crime Lab
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!The Violence Project I
Stay Connected to The Violence Project
Twitter: @theviolencepro
Future Violence Projects
One-day crisis and conflict management (CCM) training
Comprehensive mass shooter database
The Violence Project LLC
St. Paul, Minnesota
... The United States has not one gun violence problem, but several (Densley & Peterson, 2017;PERF, 2019). Everyday gun violence claims or changes hundreds of lives each week, disproportionately young Black and Latino men. ...
Technical Report
In November 2019, The Violence Project will publicly release the largest, most comprehensive database of mass shooters in the United States, developed by professors Jillian Peterson and James Densley and a team of students at Hamline University in St. Paul, Minnesota. The entire database is downloadable for free at, but it is vital that it is only used for the purpose of better understanding or preventing mass shootings. This report accompanies the public launch, providing some background on the project and a summary of topline findings. The Violence Project Database of Mass Shootings in the United States, 1966–2019, was supported by Award No. 2018-75-CX-0023, awarded by the National Institute of Justice, Office of Justice Programs, U.S. Department of Justice. The opinions, findings, and conclusions or recommendations expressed in this publication are those of the authors and do not necessarily reflect those of the Department of Justice.
... There had been indications for linkages between the incidence of gun crimes, especially homicides, and the large system of firearm manufacturing and licensed dealer distribution that existed in the United States (Diaz 1999;Koper 2007;Wiebe et al. 2009). Some federal firearms licensees (FFLs) had been connected to gun trafficking investigations and to guns diverted to prohibited users (Koper 2007;Densley and Peterson 2017). ...
The linkage between firearms and violent crime has been documented in several criminological research efforts, with different conclusions. This study explores the relationship between gun availability and gun-related violent crimes, using the city of Detroit, Michigan, as a case study. Based on the primary role of federal firearm licensees (FFLs) as a spigot for the flow of firearms into communities, spatial accessibility to FFL locations is used as a measure of gun availability. Global regression models are used to investigate the association between gun-related crime rates and spatial accessibility to FFL locations. Geographically weighted regression (GWR) is also employed to assess such spatially varying accessibility across the study area. In the global models, gun availability and selected population variables explained up to 46 percent of the variation in crime rates. The GWR model explained 59 percent of the variation in crime rates. The analysis shows a global significant positive effect of gun availability on gun-related crime rates, with strong spatial variability across the study area. The results suggest a significant linkage between gun-crime rates and spatial accessibility to FFL in the study area. Based on the findings, the location and activities of FFL dealers might be a contributing factor to the rates of gun-related crimes.
It is estimated that up to 25% of all children growing up worldwide experience child maltreatment, making it a global emergency with substantial individual and public health consequences. This chapter addresses one of the most societally pervasive consequences of child maltreatment which is known as the “cycle of victimization”. This concept depicts the increased risk of maltreated individuals to victimize others later in life, both within and outside the family environment. To understand the architecture of this victimization cycle, the chapter further sheds light on neurocognitive mechanisms aiding different forms of victimization and the buffering role of social support that could help break the cycle of victimization. Advancing our understanding of these complex and interrelated mechanisms will ultimately facilitate the design and implementation of more targeted early treatments and (preventive) interventions and support a move towards a safer society.
Full-text available
Prior research has shown that many mass shooters have explicitly admitted they want fame and have directly reached out to media organizations to get it. These fame-seeking offenders are particularly dangerous because they kill and wound significantly more victims than other active shooters, they often compete for attention by attempting to maximize victim fatalities, and they can inspire contagion and copycat effects. However, if the media changes how they cover mass shooters, they may be able to deny many offenders the attention they seek and deter some future perpetrators from attacking. We propose that media organizations should no longer publish the names or photos of mass shooters (except during ongoing searches for escaped suspects), but report everything else about these crimes in as much detail as desired. In this article, we (1) review the consequences of media coverage of mass shooters, (2) outline our proposal, (3) show that its implementation is realistic and has precedent, (4) discuss anticipated challenges, and (5) recommend future steps for consensus building and implementation.
Full-text available
Preface 1: Introduction 2: How to Test the Effects of Gun Control 3: Gun Ownership, Gun Laws, and the Data on Crime 4: Concealed-Handgun Laws and Crime Rates: The Empirical Evidence 5: The Victims and the Benefits from Protection 6: What Determines Arrest Rates and the Passage of Concealed-Handgun Laws? 7: The Political and Academic Debate 8: Some Final Thoughts Appendixes Notes Bibliography Index
Due to enhanced audience participation and involvement in content creation and distribution, crime and justice has changed. This change came about with the emergence of new digital social media and is reflected in the growth of crime and justice performances. Performances today are ephemeral renditions created and distributed in millions of social media interactions. The irony is that performances previously were created for wide heterogeneous audiences, but access was limited by time, place and medium. In contrast, new media performances are usually directed at smaller homogeneous audiences, but access is potentially unlimited due to their digital nature. In this new social media reality, the altered nature of a performance has important implications for crime and justice. Whereas crime traditionally was comprised of low visibility events in which the actors strove to hide their identities, in the new media world surreptitious crime competes with a growing number of high-visibility crimes. This article explores how the associated evolution of performance has affected crime, law enforcement and the judicial system. The impact of performance crime and justice will continue to stress criminal justice systems and change the way crime and justice is experienced in the 21st century.
In line with previous research on suicide and social contagion, there has been widespread speculation that mass killings-which often involve suicidal offenders-are socially contagious for up to 14 days. This study tested these claims by making comparisons (i) between observed chronological clusters of mass killings in the United States from 2006 to 2013 and clusters in 500 simulations containing 116,000 randomly generated dates, and then (ii) between observed mass killings receiving varying levels of public attention. No evidence of short-term contagion was found, although longer term copycat effects may exist. Further scholarly and policy implications are discussed.
This paper reviews the existing literature on the relationship between social media and violence, including prevalence rates, typologies, and the overlap between cyber and in-person violence. This review explores the individual-level correlates and risk factors associated with cyber violence, the group processes involved in cyber violence, and the macro-level context of online aggression. The paper concludes with a framework for reconciling conflicting levels of explanation and presents an agenda for future research that adopts a selection, facilitation, or enhancement framework for thinking about the causal or contingent role of social media in violent offending. Remaining empirical questions and new directions for future research are discussed.
Objective This article explores the strategic nature of framing following a focusing event. We argue that focusing events serve as catalysts for bill introductions along three particular causal stories prevalent in gun control policy: restrictive, punitive, and lenient. Methods We employ a negative binomial regression model to investigate the effect firearm focusing events have on restrictive, lenient, and punitive bills introduced in both the House and the Senate. Results Focusing events lead to an increase in restrictive, punitive, and lenient bills introduced in the House. In the Senate, however, focusing events lead to an increase in the number of punitive and lenient bills, while having no significant impact on the number of restrictive bills. Conclusion This represents an increase in attention to gun control policy regardless of the causal story.