The existing research on violence reduction largely falls into three categories: prevention, policing, and community-led interventions. Because there are many theories on the causes or drivers of violent behavior and many of them are social, economic, and cognitive, policing and recidivism strategies tend to be evaluated more frequently.

Policing Strategies

• Most are proactive, not reactive

• Require focused resources from local law enforcement and many other government agencies and organizations

• Dependent on the type of crime and local context – no one-size-fits-all strategy

• Often require additional training for law enforcement and/or technical and financial assistance from federal agencies, universities, or nonprofit organizations

Focused Deterrence (Group Violence Intervention)

Also known as pulling levers, precision policing, or group violence interventions (GVI), focused deterrence is a policing strategy targeting individuals or groups at the highest risk of engaging in violent crime, typically previous offenders. This follows the theory and evidence that crimes are concentrated among a small number of offenders in a small number of locations and shifts police and community resources to those individuals instead of taking a more general policing approach.

Focused deterrence targets a select number of individuals, sometimes networks of individuals involved in gangs or gang-activity, and engages with them through frequent interactions. These interactions occur between the individuals and a group of interveners that includes law enforcement, community organizations or a violence interrupter, and someone from local government or community organizations that can connect the targeted individuals with social services or job training. Communications are specific to the individuals. The implementation of this strategy is key to its success, however, since over-policing in this context can have detrimental effects.

The effectiveness of the program varies by intervention, with some highly effective in reducing violent crime and others having little to no impact or having a large diffusion effect. Implementation is always context dependent. Each city or town has unique circumstances, so there is no one-size-fits-all playbook for this strategy, although there are significant similarities. Trust between the community and law enforcement also plays a large role in the efficacy of the intervention, as a negative perception of law enforcement may curtail any positive impacts of the enforcement side of focused deterrence.

The components of this strategy have been developed and tested over years and include:

1. Identify specific crime problem

2. Assemble interagency enforcement group (local, state, and federal law enforcement, probation/parole officers, and state and federal prosecutors)

3. Research the target offenders or groups of offenders, including the context and patterns of their behavior

4. Develop tailored enforcement operation directed at the individuals or groups to deter potential reoffenders

5. Develop and provide matching social and community resources

6. Communicate directly and repeatedly with offenders to let them know they are under heightened scrutiny, what the consequences will be if they commit another crime, and how to avoid enforcement action[1]

A systematic review of this approach published in 2019 found that there is a moderate impact on crime.[2] Again, impacts vary based on implementation and each case study must be evaluated to determine the causes for high or low (or no) impact on the type of crime targeted. A program implemented in Philadelphia targeted offenders at crime hot spots with enhanced surveillance and enhanced sanctions if arrested. This program, known as GunStat, backfired and saw higher rates of crime at the hot spots targeted one year later as compared to hot spots not targeted, potentially indicating that the lack of social services and being tougher on offenders had the opposite effect.[3] Examples of this strategy include:

• Operation Ceasefire, Boston[4]

• Omaha Empowerment Network 360

  • “When we first started doing this, law enforcement’s role was 80-90% of what we were doing. We have progressed to a model of 30-30-30; 30% enforcement, 30% intervention, 30% prevention, it’s an ideal mix for a city,” said Schmaderer.[5] 

Hot Spots Policing

Like focused deterrence strategies, hot spots policing targets the small number of locations around a city where a large percentage of crime occurs. These locations are not neighborhoods but rather blocks, intersections, or specific addresses. Law enforcement resources are dedicated to reducing typically a specific type of crime at those locations, but the tactics to accomplish this goal vary by jurisdiction. The hot spots can be determined by local law enforcement agencies, even the districts within a police department, combining data on the locations of the targeted type of crime with patrol experience and knowledge of the locations.

Historically, hot spots policing used traditional enforcement methods to crack down on crime, like more frequent patrols, drug enforcement, and gun searches. Risk-based policing strategies target hot spots often through data analysis and risk terrain modeling (mapping) but take a problem-solving approach. Risk factors at the location are identified and multiple agencies and community organizations partner to resolve environmental designs that may encourage or facilitate crime.

Anecdotally, the Denver Police Department has implemented hot spots policing in the past and has a current strategy in place. During the first iteration, five hot spots around the city were selected for additional surveillance. This could be HALO camera placement and routine patrols to the site. Like focused deterrence, law enforcement partnered with someone who could provide social services connections to work to provide the community with solutions specific to the location and residents. At one hot spot in Denver, it was discovered that people congregated behind a pharmacy because the location had open Wi-Fi and many residents of the neighborhood did not have access to broadband internet at home. Another example is the effort undertaken in Kansas City, MO.[6]

Place Network Investigations (PNI)

Place Network Investigation strategies, like hot spot policing, understand that crime is geographically concentrated and target the locations with high ongoing rates of gun violence (typically). The locations targeted are expanded to include the network of places involved in incidents that occur at those hot spot locations. These networks include:

• Crime sites – where the crime takes place

• Convergent settings – public locations where offenders frequently meet

• Comfort spaces – private locations used for meeting, staging, and supplying

• Corrupting spots – locations that encourage criminal activity in other locations[7]

These strategies are typically used on a specific type of crime when focused deterrence and hot spots policing are insufficient to quell crime among a group of repeat offenders at repeated locations or are employed in conjunction with the other two strategies. PNI strategies require a whole of government approach to prioritize the various aspects of targeting a location, including law enforcement, parks and recreation, social services, and economic development, to name a few, as well as establishing a PNI board that coordinates at least weekly communication between all participants.

• Las Vegas: a PNI pilot program resulted in a 39% reduction (23 down to 14) in gun-related offenses at the target location over a 12-month period. The location targeted historically had high rates of gang-related gun violence. This was the only location targeted for the strategy and evaluated throughout the process.[8]

• Denver: Arnold Ventures funded a partnership with National Policing Institute to undertake a PNI strategy in Denver and five other cities. Three network locations were selected in three districts in Denver (2-East Colfax, 4-West Denver, 5-Montbello). The implementation evaluation suggests that District 4 adhered closest to the PNI model, while District 2 and 5 implementation was mixed. Monthly average changes in violent crime increased in the city by 27% comparing pre- and post-intervention, while District 2 and 5 saw a 12% and 14% increase, respectively, and District 4 saw a 27% decline.[9]

Disorder Policing

Disorder policing is an evolution of broken-windows theory and assumes that physical disorder of a location may create the conditions for crime to occur. Similar to hot spots policing, disorder policing is most effective when enforcement is paired with community and problem-solving tactics at a hot spot location.[10] A systematic review and meta analysis of this strategy found that 19 out of 30 interventions mostly across the U.S. resulted in property, violent, and disorder/drug crime reductions at the targeted location, including diffusion impacts of reduced crime in the surrounding area.[11]

• Crime Prevention Through Environmental Design (CPTED): As crime is largely concentrated in micro-locations, the built, and not built, environment can may create the conditions for violent behavior to occur. Addressing issues like poor street lighting, landscaping or growth that prohibits visibility, maintenance of built and greenspace locations, and fencing or other types of barriers may deter criminal behavior, both violent and nonviolent.

Increase Clearance Rates

Both in theory and practice, improving clearance rates for violent crimes has a deterrent effect on future crime. In 2022, clearance rates for violent crimes were at the lowest level in the U.S. since 1993.[12] According to FBI data, just over half of murders and nonnegligent homicides were cleared that year, while just 41.4% of aggravated assaults were cleared.

Factors that could inhibit, or help, the investigation of a violent crime include a lack of law enforcement resources, low trust levels between police and community members or witnesses, the relationship between the offender and victim, and the type of weapon used. Additionally, more investigative efforts are typically dedicated to solving homicides, while nonfatal shooting and other gun-related assaults receive less attention in departments with lower staffing or training levels.

Based on time to clearance data from Boston from 2010 to 2014, the longer a nonfatal shooting investigation is open, the less likely it is to be cleared.[13] The Denver Police Department started a team in 2020 to help solve nonfatal shootings, the Firearm Assault Shoot Team (FAST). According to DPD, nonfatal shooting clearance rates almost tripled between 2020 and 2023.[14] Additional tactics to increase clearance rates can be found here.[15]

Community-Oriented Policing

As opposed to community-led violence interventions, community-oriented policing is law enforcement led engagement with the community to build relationships and work collaboratively with residents and organizations. This frequently involves a shift in culture to include the community in problem solving to prevent and solve crime. These tactics have become more important and more common over the last decade.

This strategy is also proactive as it involves law enforcement doing outreach to community members through meetings, events, solving problems through greater officer autonomy, and accountability. While this strategy may not have a direct relationship to crime reduction, it works to build trust and legitimacy which will help in solving crimes and showing community members law enforcement is there to support the community. Without this trust, it becomes more difficult to carry out the other police-led interventions included here.

Gun Violence Intervention and Prevention[16]

As gun violence has risen in the U.S., all levels of government and nonprofit, community-led organizations have been working to try and reduce the harm caused by firearms. Gun violence interventions can be police-, legislative-, community-, and healthcare-led strategies, with law enforcement leading interventions while community and healthcare focused organizations leading on prevention, and policymakers focusing on both.

Interventions can take the form of various policing tactics, such as cracking down on the illegal firearm trade, firearm theft, enforcement of laws, focusing evidence-based interventions on gun-violence offenders (focused deterrence, hot spots policing, etc.), and increasing clearance rates. Myriad policies have been enacted to try and curb gun violence in recent years. One analysis of states’ Brady scores, which rank the strength of gun laws in a state, evaluated the number of firearm injuries by using hospital admission data by their Brady score. The authors found that the stricter the gun laws (or the higher the Brady score), the fewer firearm-related injuries.[17] Some of the policies include:

• Gun dealer regulations

• Assault weapon and large capacity magazine bans

• Child access restrictions and safe storage

• Extreme Risk Protection Orders (Red flag laws)

• Mandatory background checks and waiting periods before purchase

• Restrictions on guns in public places

The U.S. Department of Justice collaborated with the Council for Criminal Justice (CCJ) to help inform the White House’s initiative on gun violence prevention. They formulated Ten Strategies to Reduce Gun Violence – Council for Criminal Justice (CCJ)

• In 2023 DOJ recommended steps to reduce gun violence as researched by CCJ

1. DOJ page and grant opportunities, including free training and technical assistance[18]

2. Report[19]

Steps:

1. Set a clear goal to stop violence

2. Identify key people and places driving violence

3. Create citywide plan for engaging key people and places

4. Engage key people with empathy and accountability

5. Address key locations using place-based policing and investment

6. Place responsibility for violence reduction efforts at the top

7. Emphasize healing with trauma-informed approaches

8. Invest in anti-violence workforce development

9. Set aside funding for new stakeholders and strategies

10. Commit to continuous improvement based on data, evidence, and peer-to-peer learning

Community-Led Interventions

Public Health Approach to Violence Prevention

Note: In some discussions of evidence-based violence reduction strategies, the public health, community-led, and youth-violence prevention approaches are treated as separate approaches. Because many public health interventions are community-led and community-led organizations use the public health approach to target youth violence, the three are combined here.

The goal of the public health approach to violence prevention is solving the underlying drivers of violence. Violence is treated as a societal problem as it shares characteristics with epidemics. According to the Center for Disease Control and Prevention, the model used to approach this public health problem consists of analysis and intervention at four levels: individuals, relationships, community, and societal.[20] Each level identifies the risk factors that may lead to violent behavior or victimization with strategies to address each factor to prevent violence, as seen in the visual below.[21] These levels are then evaluated using the following methodology:

1. Define and monitor the problem

2. Identify risk and protective factors

3. Develop and test prevention strategies

4. Ensure widespread adoption[22]

This approach is multidisciplinary and extends beyond the public health sector to include community and governmental organizations with or without law enforcement. As a preventative strategy, the scope and results are longer term and may not have short term impacts on violence levels. It is also more difficult to track and measure outcomes over a longer period, especially as the interventions that fall under the public health umbrella vary widely from youth sports programs to cognitive behavioral therapy and many are universally offered (as opposed to targeted to high-risk populations).

A systematic review of a wide array of public health intervention evaluations concluded that the programs with the highest success rates were youth sports programs, particularly traditional martial arts, and anti-bullying programs.[23] The same analysis found that psychosocial interventions had smaller impacts on violent crime.

Because there are many drivers of crime, the interventions under a public health approach are extensive. These approaches are often complemented by policing interventions, like the focused deterrence intervention, but many are exclusively community led. Below are a dozen examples of community-based approaches, but it does not represent all iterations of the strategy:

• Violence interrupters and street mediation

• Athletics and arts programs

• Cognitive behavioral therapy and behavioral/mental health programs for individuals and families

• Youth work programs and workforce development and training

• Anti-bullying programs

• Gun violence prevention programs

• Substance abuse treatment

• Educational and truancy-reduction programs

• Hospital interventions for victims of violent crime

• Co-responder programs with or without law enforcement

Some examples of community-led public health violence prevention interventions are listed below:

• CURE Violence: Evidence is mixed and inconclusive as to whether it directly resulted in a reduction in violent crime during the period and locations measured.[24]

• Communities That Care: A prevention-based system with positive, albeit moderate results that targets youth to prevent substance abuse, violence, and other high-risk behaviors.[25]

• Youth Violence Prevention Centers: An initiative by the CDC and partnering with CU Boulder’s Center for Youth Violence Prevention, YVPCs pair community organizations with academics to reduce youth violence. The center in the Montbello neighborhood in Denver used the Communities That Care model and saw a 37% reduction in delinquency among 10–11-year-olds over five years.[26]

Footnotes

1. McManus, Hannah D et al. Street Violence Crime Reduction Strategies: A Review of the Evidence. Center for Police Research and Policy, February 2020, page 8.

2. Braga AA, Weisburd D, Turchan B. Focused deterrence strategies effects on crime: A systematic review. Campbell Systematic Reviews. e1051. https://doi.org/10.1002/cl2.1051.

3. Sorg, E. (2015). An ex post facto evaluation of the Philadelphia GunStat model. ProQuest Dissertations Publishing.

4. https://scholar.harvard.edu/files/cwinship/files/pulling_levers_skeptic_-_second_edition_update.pdf

5. https://www.cityofomaha.org/latest-news/1008-omaha-s-crime-reduction-strategy-becomes-national-model

6. Caplan, J. M., Kennedy, L. W., Drawve, G., & Baughman, J. (2021). Data-informed and place-based violent crime prevention: the Kansas City, Missouri risk-based policing initiative. Police Quarterly. https://doi.org/10.1177/10986111211003205

7. Herold, TD, Engel, R, Corsaro N, Clouse SL. Place Network Investigations in Las Vegas, Nevada: Program Review and Process Evaluation. UC Center for Police Research and Policy. March 2020.

8. Ibid.

9. Engel, RS and Pietenpol, A. Denver Place Network Investigations (PNI) Initiative Evaluation. National Policing Institute. Presentation to DPD on November 30, 2023.

10. Braga AA, Welsh BC, Schnell C. Disorder policing to reduce crime: A systematic review. Campbell Syst Rev. 2019 Sep 8;15(3):e1050. doi: 10.1002/cl2.1050. PMID: 37131517; PMCID: PMC8356497.

11. Ibid.

12. https://www.pewresearch.org/short-reads/2024/04/24/what-the-data-says-about-crime-in-the -us/#:~:text=Nationwide%20clearance%20rates%20for%20both,1993%2C%20the%20FBI%20data%20shows.&text=Police%20cleared%2052.3%25%20of%20reported,down%20from%2064.1%25%20in%202013.

13. Braga, A. Improving Police Clearance Rates of Shootings: A Review of the Evidence. https://media4.manhattan-institute.org/sites/default/files/improving-police-clearance-rates-shootings-review-evidence-AB.pdf

14. https://www.themarshallproject.org/2023/10/30/nonfatal-shootings-police-clearance-rates-denver

15. https://nationalcaseclosed.org/toolkit/docs/14876_NCCP_Translational_Brief_State_of_Evidence_5-17-23.pdf

16. https://www.rand.org/research/gun-policy.html

17. Jehan F, Pandit V, O'Keeffe T, Azim A, Jain A, A Tai S, Tang A, Khan M, Kulvatunyou N, Gries L, Joseph B. The burden of firearm violence in the United States: stricter laws result in safer states. J Inj Violence Res. 2018 Jan;10(1):11-16. doi: 10.5249/jivr.v10i1.951. Epub 2017 Nov 11. PMID: 29127770; PMCID: PMC5801608.

18. https://www.ojp.gov/violent-crime-reduction-roadmap/introduction

19. https://counciloncj.org/wp-content/uploads/2024/06/VCWG-Final-Report.pdf

20. https://www.cdc.gov/violence-prevention/about/index.html

21. https://www.who.int/groups/violence-prevention-alliance/approach

22. Centers for Disease Control and Prevention, "The Public Health Approach to Violence Prevention," Atlanta, Ga.: Author, 2013.

23. Fazel S, Burghart M, Wolf A, Whiting D, Yu R. Effectiveness of Violence Prevention Interventions: Umbrella Review of Research in the General Population. Trauma Violence Abuse. 2024 Apr;25(2):1709-1718. doi: 10.1177/15248380231195880. Epub 2023 Aug 31. PMID: 37650521; PMCID: PMC10913357.

24. Butts, J. A., Roman, C. G., Bostwick, L., & Porter, J. R. (2015). Cure violence: a public health model to reduce gun violence. Annual review of public health, 36(1), 39-53.

25. Mears, D. P. (2024). The Oxford handbook of evidence-based crime and justice policy. Oxford University Press.

26. https://www.cdc.gov/youth-violence/php/yvpcs/accomplishments.html