By Everytown for Gun Safety and Johns Hopkins Center for Gun Violence Solutions. ( 

Extreme Risk Protection Order (ERPO) laws create an opportunity to intervene and prevent firearm violence when there are warning signs that an individual poses a risk of harm to self or others. While ERPO laws are relatively new, a growing body of research demonstrates the potential for these laws to prevent firearm violence, particularly firearm suicide, and multiple victim/mass shootings. Interest in ERPO laws has increased in recent years, with 16 states having enacted these laws between 2018 and 2023. Implementation varies widely across and within states. As a result of strong ERPO implementation efforts in some jurisdictions, more information is now available for state and local leaders about how to implement and adapt ERPO laws for their own communities. In addition, the Bipartisan Safer Communities Act of 2022 included $750 million in new federal grant funding for states, some of which is designated to support ERPO implementation. To meet this moment, the Everytown for Gun Safety Support Fund and the Johns Hopkins Center for Gun Violence Solutions have partnered to compile this guide of the best available practices and promising approaches to effective implementation of extreme risk laws. These recommendations are informed by conversations with individuals who are pioneering ERPO implementation, in addition to the best practices shared at a December 2022 convening of ERPO leaders from around the country.   

New York; Baltimore: The Authors: 2023. 52p.  

By The Philadelphia Interagency Research and Public Safety Collaborative (PIRPSC)

Firearm violence in Philadelphia is a public health crisis. In 2021, Philadelphia suffered a record number of fatal criminal shooting victims (501) and non-fatal criminal shooting victims (1,850). Philadelphia has also experienced extraordinary recent increases in arrests for illegal firearm possession and crime guns recovered, while the Commonwealth has recorded record gun sales in 2020. Despite this crisis in gun violence, shooting arrest rates remain low, conviction rates in illegal gun possession cases have been declining since 2015, and conviction rates in shooting cases declined between 2015 and 2019 and increased modestly in 2020 and 2021.

Firearm violence in Philadelphia is a racial justice crisis. Shootings disproportionately impact Black communities: in Philadelphia over 80% of shooting victims and 79% of arrestees have been Black since 2015. Both victims and arrestees overwhelmingly come from disadvantaged neighborhoods that are majority non-white, have high rates of poverty and unemployment, and less likely to have a high school degree or diploma. Endemic violence in these communities means that the vast majority of those arrested for gun violence have themselves been previously traumatized, often as a witness to previous violent acts; over 80% have previously accessed or been screened for behavioral health services through the City. Because the causes of gun violence are complex and varied, so are the solutions. Addressing the gun violence crisis requires a comprehensive strategy with elements of enforcement, intervention, and prevention to achieve both short-term and long-term reductions in gun crimes. Collaboration among city agencies, including law enforcement and non-law enforcement agencies is critical to successfully implement such a comprehensive strategy. Reviews of evidence-based practices, along with data analysis of local data, have helped us to come to key findings related to gun violence in Philadelphia and have informed recommendations to stem that violence. Readers are encouraged to read both the summary, below, as well as the report in its entirety to understand the context of our recommendations as well as the limitations in both our data and data analyses. 

Philadelphia: Philadelphia Interagency Research and Public Safety Collaborative (PIRPSC)    2022. 196p.  

By Jillian Carr

Gunshot detection systems are used by policing agencies across the U.S. to detect incidents of firearms discharge. The most commonly used gunshot detection system is ShotSpotter, currently deployed in more than 100 cities across the U.S.1 Such systems typically use sensors, placed strategically throughout a particular area, to pinpoint the location of gunfire. Agencies that adopt the technology hope that it can help them reduce gun violence and make communities safer. They report that the technology can alert officers to gunshots that otherwise would not be reported, and that it can reduce officer response times by directing them to a more precise location. But the technology can be quite expensive—costing several hundred thousand dollars or more per year to maintain.

We found that in areas of St. Louis County that used ShotSpotter technology, police were alerted to four times as many gunshot incidents during the study period than in comparable areas without the technology. Despite responding to more calls related to gunfire, we found that reported assaults, which include gun-related assaults, fell by roughly 30 percent in areas with ShotSpotter. Moreover, the technology did not produce changes in the number or pattern of arrests. Because we did not find racially disparate effects on the prevalence of crime reporting or arrests from the adoption of the technology, ShotSpotter’s social costs appear minimal.

New York: Policing Project at New York University School of Law, 2021. 18p.

By Charles M. Katz, Michaela Flippin, Jessica Huff and William King

In 2017, the Phoenix (AZ) Police Department was awarded BJA funding for establishing the Phoenix Crime Gun Intelligence Center (CGIC). The CGIC was a collaborative partnership of law enforcement agencies and experts including the Department's Crime Gun Intelligence Unit (CGIU), the Police Crime Laboratory, the Maricopa County Attorney's Office, the ATF's Phoenix Field Division, and Arizona State University’s Center for Violence Prevention and Community Safety. .. Overall, we found the CGIC's processes, as determined by its written policies and procedures, to have been consistently carried out as planned, and their impacts for the most part to be as expected or trending in a positive direction.

Phoenix, AZ: Center for Violence Prevention & Community Safety, Arizona State University. 2021. 68p.

By Jaclyn Schildkraut

The May 24, 2022, mass shooting at Robb Elementary School in Uvalde, TX, where 19 fourth grade students and two of their teachers were killed and 17 others were injured, reignited a national discourse about preparing school communities for similar tragedies. Proposals ranging from armed teachers to clear backpacks were circulated, despite the lack of empirical evidence to support their efficacy in situations like Uvalde. This leaves an important question for stakeholders charged with keeping school communities safe: what is the best way to reduce the harm caused by these events that is evidence-based?.

Despite the widespread use of lockdown drills in US schools, the conversation about their efficacy remains contentious and often is not guided by empirical evidence. This brief provides an overview of the scholarly evidence surrounding lockdown drills, as well as considerations of best practices, an important foundation for policymakers tasked with keeping students and staff safe and for the public to better understand their utility in schools.

Albany, NY: Rockefeller Institute of Government, 2022. 20p.

By Chris Eades, Roger Grimshaw, Arianna Silvestri. and Enver Solomon

The Centre for Crime and Justice Studies (CCJS) first published this briefing paper in August 2006. It received widespread media coverage and a great deal of interest from the police, voluntary sector organisations and members of the public. This review aims to draw together some of the existing information and research on these issues and makes tentative assessments of the programmes in place to combat knife usage. The paper begins by providing information from the available sources on the extent of the problem as it pertains to different levels of seriousness: the carrying of knives; the use of knives in crime; and the use of knives in homicides. It then investigates possible reasons for knife carrying before establishing which sections of the population are most likely to suffer knife-related offences. Next, assessments are made of the current strategies being considered or used to reduce levels of knife carrying and knife use. These include the national knife amnesty, police stop and search, increased prison sentences, education and awareness-raising, and prevention strategies.

London: Centre for Crime and Justice Studies, King’s College London, 2007. 36p.

By William Godnick

This monograph is a modified version of a background paper prepared for a conference that took place in Ottawa, Canada in May 2001, bringing together representatives of the Member States of the Organization of American States (OAS), non-governmental organizations (NGOs) and civil society to discuss issues related to the July 2001 United Nations (UN) Conference on the Illicit Trade in Small Arms and Light Weapons in All Its Aspects (hereafter referred to as the UN Conference). This version takes into account the Programme of Action (PoA) adopted by the UN Member States as well as other emerging or consolidated initiatives in the western hemisphere.

British American Security Information Council, International Alert and Saferworld, 2002. 26p.

By U.S. Bureau of Justice Assistance

Throughout the United States, violence involving firearms remains at an alarmingly high rate. The Federal Bureau of Investigation’s 1996 Uniform Crime Reports indicates that firearms were used in 29 percent of all murders, robberies, and aggravated assaults in the United States in that year. According to the Centers for Disease Control and Prevention, firearms-related violence is a leading cause of injury-related death, second only to automobile-related fatalities. To stop the illegal flow of firearms to persons with criminal intent, law enforcement must develop strategies to address problems with gun dealers, stolen weapons, and illegal purchasers and suppliers. Furthermore, law enforcement cannot ignore the role that both nonlicensed and dishonest licensed firearms dealers play in the illegal movement of weapons. To address the illegal firearms trafficking issue, the Bureau of Justice Assistance created the Firearms Trafficking Program in fiscal year 1993. Three different initiatives were funded under this program: the Firearms Licensee Compliance Program, the Firearms Investigative Task Force Program, and the Innovative Firearms Program. Demonstration sites under each of these three initiatives were visited to identify goals, lessons learned, and promising practices and approaches of each project.

Washington, DC: U.S. Bureau of Justice Assistance, 2000. 96p.

By Philip Alpers and Amélie Rossetti

Four consecutive formal reports have now found that no Australian State or Territory has at any stage fully complied with the 1996 or 2002 firearm resolutions which collectively formed the National Firearms Agreement. In important areas, State and Territory legislation has been blocked or revised to dilute the effect of the NFA. This report, commissioned and funded by Gun Control Australia, finds that on balance, both non-compliance from day one and two decades of political pressure have steadily reduced restrictions and undermined the NFA’s original intent.

Sydney: Gun Control Australia, 1997. 102p.

By Michael Rocque, Grant Duwe, Michael Siegel, James Alan Fox, Max Goder-Reiser, and Emma E. Fridel

In the past decade, mass shootings, particularly those that take place in public areas, have increasingly become part of the national conversation in the United States. Mass public shootings instill widespread fear, in part because of their seeming randomness and unpredictability. Yet when these incidents occur, which has been with somewhat greater frequency and lethality as of late, public calls for policy responses are immediate. In this policy brief, we review efforts to evaluate the effect of gun control measures on mass public shootings, including a discussion of our recently published study on the relationship between state gun laws and the incidence and severity of these shootings. The findings of this work point to gun permits and bans on large capacity magazines as having promise in reducing (a) mass public shooting rates and (b) mass public shooting victimization, respectively. Interestingly, however, most gun laws that we examined, including assault weapon bans, do not appear to be causally related to the rate of mass public shootings.

Albany, NY: Rockefeller Institute of Government, 2021. 20p.