Identifying high‐risk firearm owners to prevent mass violence

• DOI: http://doi.org/10.1111/1745-9133.12477
• Author: Garen J. Wintemute,Hannah S. Laqueur
• Published date: 01 February 2020
• Date: 01 February 2020

DOI: 10.1111/1745-9133.12477

SPECIAL ISSUE ARTICLE

COUNTERING MASS VIOLENCE IN THE UNITED STATES

Identifying high-risk firearm owners to prevent mass

violence

Hannah S. Laqueur Garen J. Wintemute

University of California—Davis

Correspondence

HannahS. Laqueur, Department of Emergency

Medicine,University of California—Davis,

2315Stockton Blvd., Sacramento, CA 95817.

Email:hslaqueur@ucdavis.edu

Theaut hors’ workon this ar ticle wassupported

bygrants from the National Institute of Justice,

Officeof Justice Programs, U.S. Department of

Justice(2014-R2-CX-0012 and 2018-75-CX-

0026),California Wellness Foundation (2014-

255),Heising-Simons Foundation (2017-

0447),New Venture Fund (NVF) Fund for Safer

Future(A19-2744), and UC Davis Violence

PreventionResearch Program and UCFC, the

Universityof California Firearm Violence

ResearchCenter. The opinions, findings, and

conclusionsor recommendations expressed in

this publication/program/exhibitionare those of

the authors and do not necessarily reflect those

oft he funders.

Research Summary: In this article, we detail recent efforts

in California to identify and target high-risk firearm owners

to help prevent firearm violence, including mass shootings.

We begin by describing gun violence restraining orders,

also known as extreme risk protection orders, which pro-

vide a judicial mechanism for firearm recovery and a time-

limited prohibition on firearm purchases. Next, we dis-

cuss California’s Armed and Prohibited Persons (APPS)

database and enforcement system. APPS is used to identify

newly prohibited persons among legal firearm owners and

to help law enforcement recoverthose firear ms. Finally, we

highlight early research in which machine learning for rare

event detection is employedto forecast individual risk using

California’s decades worth of firearm transaction records

and other readily available administrative data.

Policy Implications: The approaches described range in

scale, scope, and strategy, but all three allow for targeted

intervention at times of heightened risk. In so doing, they

offer the potential to provide outsized benefits to efforts to

prevent mass violence.

KEYWORDS

California firearm policy, extreme risk protection orders, public mass

shootings, risk prediction

Criminology & Public Policy. 2020;19:109–127. wileyonlinelibrary.com/journal/capp © 2019 American Society of Criminology 109

110 LAQUEUR AND WINTEMUTE

As soon as I saw those cops, the biggest fear I had ever felt in my life overcame me. I

had the striking and devastating fear that someone had somehow discovered what I was

planning to do, and reported me for it. If that wasthe case, the police would have searched

my room, found all of my guns and weapons, along with my writings about what I plan to

do with them. I would have been thrown in jail, denied of the chance to exact revenge on

my enemies.

—Elliot Rodger, “My Twisted World,” 2014 p. 134

On May 23, 2014, 22-year-old Elliot Rodger killed 6 people and injured 14 others in Isla Vista,

California, near the campus of the University of California—Santa Barbara. Less than a month before

the attack, the Santa Barbara Sheriff’s Department had gone to Rodger’s residence in response to

reports of concern from his parents. But the department later reported that the suspect did not show

any signs of being, or make any statements indicating that he was, a danger to himself or others

(Brown, 2014, para.1). Had they searched Rodger’s room, or searched California’scentralized database

of firearm transaction records, they would have discoveredthat he had recently legally purchased three

semiautomatic handguns from a Southern California gun shop. He also had more than 400 rounds of

ammunition stored under the bed.

Ex post, the Isla Vista massacre, like many incidents of mass violence, seems preventable. As is

often the case, the perpetrator demonstrated a period of deterioration marked by increasingly ominous

manifestations of dangerousness preceding the event. In the yearsand months leading up the attack, he

legally purchased several firearms and large quantities of ammunition. He visited shooting ranges on

multiple occasions. But many individuals who are at high and imminent risk for violence to themselves

or others do not meet any existing criteria for prohibiting access to firearms. Furthermore, identifying

such individuals can be challenging, and many individuals who exhibit risky behavior never go on to

commit major acts of violence.

In this article, we describe recent efforts in California to identify and target high-risk gun owners

to help prevent mass shootings and other forms of firearm violence. We begin with a discussion of

California’s gun violence restraining order (GVRO) policy, which was established by lawmakers in

response to the Elliot Rodger case. With GVROs (most commonly known as extreme risk protection

orders), courts are allowed to have firearms removed fromt hose theyjudge to be at high and imminent

risk of violence and to prohibit such persons from purchasing firearms for the duration of the order.

GVROs have been used in efforts to prevent mass shootings in California, apparently with positive

results (G. Wintemute et al., 2019).

Next, we highlight the development of California’s Armed and Prohibited Persons System (APPS).

APPS is used by law enforcement to identify persons who acquired firearms legally but subsequently

experienced a disqualifying event such as a convictionfor a felony or violent misdemeanor, a domestic

violence restraining order, or an emergency psychiatric hospitalization for dangerousness to them-

selves or others. California Department of Justice (CA DOJ) law enforcement teams are then charged

to retrieve these unlawfully possessed weapons. Although prohibitions on firearm purchases by high-

risk persons and background checks to enforce purchase prohibitions have broad public and scientific

support (Barry, McGinty, Vernick, & Webster, 2013; Wright, Wintemute, & Rivara, 1999), almost

no attention has been given to enforcing existing restrictions on ownership among those who become

prohibited persons after a legal firearm purchase. This gap is important to fill not only because pro-

hibiting events are general indicators of risk, but also because transitions to prohibited-person status

occur as the result of events associated with increased risk for violence in the near future (Blumstein

& Nakamura, 2009).