Program Profile: Philadelphia (Pa.) Focused Deterrence Strategy

This was a focused deterrence violence-reduction strategy involving enforcement and services to targeted individuals to address gun and gang violence. The program is rated Promising. There were statistically significant reductions in community-level criminal shootings in treated areas, compared with matched comparison areas, and in shootings around treated gang territories, compared with areas around matched comparison gang territories, at 2 years’ postimplementation.

A Promising rating implies that implementing the program may result in the intended outcome(s).

A Promising rating implies that implementing the program may result in the intended outcome(s).

Program Goals/Target Population

After Philadelphia, Pa., experienced a sustained increase in violence in 2010, the mayor, the Philadelphia District Attorney’s Office, and the Philadelphia Police Department initiated a citywide effort to review potential violence reduction strategies that the city could implement. By fall 2012, this working group had become familiar with Operation Ceasefire in Boston (Mass.), the original “pulling levers” focused deterrence model, which is typically known as the Group Violence Intervention when directed at gang or group violence (Roman et al., 2020). (Philadelphia now implements the Group Violence Intervention model, which is distinct from this Focused Deterrence strategy. Please see the Implementation section below for information on the current Philadelphia Group Violence Intervention program). The “pulling levers” strategy involves deterring violent behavior by reaching out directly to gang members, saying explicitly that violence will not be tolerated, and by following every legally available route when violence occurs (Braga et al. 2001). The working group began to explore the feasibility of introducing the intervention model to Philadelphia, where it became known as the Philadelphia Focused Deterrence Strategy.

The general approach of the Philadelphia Focused Deterrence Strategy consisted of 1) law enforcement’s directed deterrence message (at “call-in” meetings), and follow-through to targeted individuals (“pulling levers”), 2) offers of social services and support, and 3) use of community moral voices to develop and maintain informal social control. The goal of the strategy was to reduce shootings by combining the threat of enforcement with the provision of services and targeting them to individuals committing violence in the community.

Target Area/Key Personnel

The South Police Division—which includes three police districts and encompasses most of South Philadelphia—was chosen as the geographic focus of the strategy, because of its known street gang involvement in gun violence and the preexisting interagency relationships among law enforcement in that area, including regular gang intelligence sharing between the District Attorney’s Office and Police Department. Further, the overall geographic area is relatively small, compared with other police divisions across Philadelphia, and was perceived to be manageable for problem-solving because the gang territories were clustered close together (Roman et al., 2019). The executive team for the focused deterrence strategy was formed in late 2012 and included leaders from the District Attorney’s Office, the Philadelphia Police Department, the Mayor’s Office, First Judicial District of Pennsylvania’s Adult Probation and Parole Department, Juvenile Probation, the Philadelphia Housing Authority Police Department, social service agencies, researchers, and the local federal prosecutor’s office. At the time of the first call-in meeting in Philadelphia in 2013, there were 16 active gangs that became the initial focal point of the initiative.

Program Components

The first step was the call-in meeting, which was conducted with individuals belonging to street groups identified as the drivers of violence. At these meetings, law enforcement conveyed a clear message that gun violence would no longer be tolerated and, if a shooting by a member of a group occurred after the call-in, law enforcement would use all enforcement options available to target the group involved in the shooting. Gang members also were asked to share these messages with other members of their groups (Roman et al., 2017). Individuals who were invited to the call-in meetings and did not attend had warrants issued for their arrest. Thus, when a shooting occurred and the Police Department and the District Attorney’s Office determined that it involved a member of a targeted South Philadelphia group, the District Attorney’s Office immediately furnished a current list of all members of that group and sent it to all the law enforcement partners. Numerous actions then occurred as part of an enforcement effort, each limited only to the identified members of the targeted gangs. The “levers pulled” included the execution of outstanding warrants; prosecutorial requests for high bail; requests for longer sentences; probation revocation; testimony by members of the South Gang Task Force (10 officers who were dedicated to the focused deterrence strategy) at the preliminary misdemeanor or felony case hearings; increasing the supervision of individuals on probation and parole; housing code enforcement; and increased enforcement of outstanding child support payments (Roman et al., 2020). The executive team that led the strategy also employed several levers beyond traditional law enforcement sanctions, including working directly with public utilities to terminate service for nonpayment or illegal electric and gas connections, and facilitating a review of public housing eligibility.

Social services and the involvement of community-based assets also played roles in the Philadelphia strategy. The purpose was to offer a positive incentive, in addition to the threat of severe consequences, for targeted individuals. Most individuals were recruited for services immediately after the call-in meetings. The Mayor’s Office also coordinated community outreach, which included developing and distributing materials that summarized the strategy and working with community leaders to promote an understanding that the strategy was focused not on arrest and incarceration, but on delivering a message of collective accountability and creating social pressure that could deter violence. A community outreach coordinator, who was a resident of the area targeted by focused deterrence, acted as the primary liaison between law enforcement and the community. The outreach coordinator ran monthly community meetings, where residents could voice their issues and concerns, and led the development of numerous prevention efforts to reach young children, which included a basketball league and neighborhood service projects.

Program Theory

The focused deterrence/pulling levers model is grounded in classic deterrence theory (Beccaria, 1986; Bentham, 1988). The basic premise of the theory is that when the costs of committing a crime outweigh the benefits, the crime should be prevented. Deterrence comprises three main principles: certainty, severity, and celerity of punishment (Nagin, Solow, and Lum, 2015). Specifically, in the Philadelphia Focused Deterrence Strategy, the deliberate, personalized communication and follow-up enforcement activity after shootings was designed to show targeted individuals that committing a shooting would be costly to them and their group (Roman et al., 2020), by demonstrating the high certainty of punishment. In addition, the model was designed not only to increase the certainty of punishment but also, with some levers, to increase the severity of punishment. The third factor of the focused deterrence model, celerity, included in the Philadelphia Focused Deterrence Strategy, was intended to show that combined resources of the partner agencies working together to solve shootings could yield swift outcomes (Roman et al., 2020).

Study

Roman and colleagues (2019) used a quasi-experimental design with propensity score matching to assess the effectiveness of the Philadelphia Focused Deterrence Strategy on community- and gang-level violence during a 2-year post-implementation period. The first call-in notification meeting in the city was held April 17, 2013, which became the period of implementation onset. During the first 2 years of focused deterrence (the evaluation period), there were four call-in meetings and 16 enforcements. Of the four call-in meetings held during this period, there were 45, 29, 28, and 29 gang members in attendance at each event, respectively.

For both the community- and gang-level analyses, the key outcome of interest was criminal shootings. Shootings included fatal and nonfatal criminal shootings (which excluded officer shootings and self-inflicted shootings) and were counted at the victim level (i.e., one person shooting three people equals three shootings). Address-level data for all criminal shootings were received from the Philadelphia Police Department for the period of 2003 through March 2015.

For the community-level analyses, census block groups were the unit of analysis, where aggregations of the block groups represented the target areas and matched block groups represented the counterfactual. The dependent variable was modeled as the monthly rate of shootings per 1,000 residents. Through propensity score matching techniques, criminal shootings in the treatment neighborhoods were compared with those of a matched set of comparison neighborhoods outside of South Philadelphia. A matching-with-replacement routine was used, which allowed a given untreated block group to be included in more than one matched set, because of the unique characteristics of South Philadelphia that made it difficult to find a large pool of appropriate matches. The factors used in the treatment status matching model were the rate of shootings and robberies with a gun for the preintervention year (2012); policing activity, measured as the level of car and pedestrian stops, made by the Philadelphia Police Department in 2012; count of street gangs in 2013; count of active individuals on probation or parole during 2009–10; and the following four demographic variables derived from Census American Community Survey data for 2007–11: 1) concentrated disadvantage (included measures of public assistance, unemployment, poverty, and female-headed households); 2) percentage of the population that identifies as any part Black; 3) percentage of the population that is Hispanic; and 4) total population. Post-matching demonstrated that the treatment group (146 residential block groups) and comparison group (102 block groups, some of which were used more than once in the matched treatment–comparison pairs) were balanced, and no statistically significant differences in the factors included in the model were observed between the two groups.

For the gang-level analyses, gangs in the target areas were matched through propensity score models with similar groups outside of the target areas and compared on shooting activity in the geographic area around each gang territory. The Police Department provided data on gangs, territory size and location, members, and other characteristics of the gangs and specific members. Detailed group-level data existed in a systematic form through the department’s Central Intelligence Unit. Law enforcement and other local agencies verified details about each group, including members, associates, size, activity, and geographic location down to the block level. A separate process was implemented by the Central Intelligence Unit to identify the shootings that were gang related, from 2009 through March 2015. Propensity score matching techniques were used to identify comparison gangs. Mahalanobis metric matching, one-to-one with replacement, was used to estimate multivariate distances between each treated gang and all active gangs outside of the South Division as a function of the following 12 factors related to the nature of gangs and gang-related behavior: 1) the number of shootings and gun robberies that occurred within a quarter-mile buffer from the center of each gang’s turf during 2012; 2) the number of people who were validated as gang members during the police audit meetings that occurred from 2014 through January 2015; 3) the number of people who were validated as being associated with the gang but not considered members, per the gang audit meetings; 4) the average age of gang members in 2013; 5) designated street gang (derived from a three-category classification of groups used by the Police Department for gangs: street gangs, drug-trafficking organizations, or corner drug sales); 6) the number of public housing developments that fell within or touched a gang territory; 7) the number of enduring drug markets located in or adjacent to the gang’s territory; 8) concentration of gangs in a quarter-mile buffer area; 9) concentration of gangs in an eighth-mile buffer area (two measures were created to capture the density of gangs and their proximity to each other, as a measure of competition and potential conflict); 10) aggregate count of the home location of individuals on probation or parole during 2009–10, within a half-mile buffer around the center of each gang’s set space, because these individuals were directly targeted by the strategy through the call-in notification meetings; 11) average of concentrated disadvantage scores for any block group that overlapped or fell within a gang’s set space; and 12) residential stability (homeowners residing in their homes for at least 5 years, and percentage of owner-occupied households) surrounding the gang’s set space. The matching procedure matched 14 treatment gangs with 14 comparison gangs. After matching, there were no statistically significant differences between treatment and comparison gangs on any of the variables.

Difference-in-difference estimation was used to model the community-level impact of the strategy. Change over two periods of time was examined—before the focused deterrence treatment and after the treatment—in relation to changes between the treatment and comparison areas. The models included controls for month and year to account for fluctuations in shootings over the time series.

For the gang-level analyses, three different sets of analyses were conducted. The CrimeSolutions review of this study focused on the first set that compared all shootings in focused deterrence gang territories with all shootings (not only gang-related shootings) in the territories of matched comparison gangs. Two buffer zones were created around the center of each gang’s home turf: a smaller quarter-mile buffer zone that encompassed approximately 0.2 mile, and a larger half-mile buffer zone that included about 0.8 mile. Any shootings that occurred within them were summed. Difference-in-difference estimation was also used to test the difference in pre–post change of buffer-area shootings for the treated gangs, compared with matched comparison gangs, as of April 2013. Average gain score comparisons and growth curve models were used for the analyses. The quarterly growth curve model was set up with an indicator designating whether a street gang was in the treatment group or in the comparison group and whether the period was before implementation or postimplementation. Seasonal variations in quarterly shootings were accounted for in the analyses, and frequency weights were used to account for the matching with replacements. Additionally, a second set of analyses consisted of pre–post only negative binomial regression random effects models matching the timing of two intervention components (the call-in meetings and enforcement actions) as applied to each targeted gang to examine changes in shootings in buffer areas around gang territories. In the last set of models, negative binomial regression random effects models matching the timing of the intervention as applied to each gang were also run to examine shootings attributed to each specific targeted gang (including gang members committing the offense, gang member as victim, gang member as witness/bystander, and gang shootings with all types combined). No subgroup analyses were conducted.

The Philadelphia Focused Deterrence Strategy was active until the beginning of 2017. In August 2020 the city launched a pandemic-modified version of the Group Violence Intervention strategy as part of its goal of reducing shootings by 30 percent by the end of 2023. Group Violence Intervention is separate and distinct from the formerly implemented Focused Deterrence Strategy. For more information on Group Violence Intervention in Philadelphia including specific components, the geographic focus, and partner agencies, please see the 2021 progress update.

Subgroup Analysis

Roman and colleagues (2019) examined the timing of the Philadelphia Focused Deterrence strategy (call-in meetings only, enforcement actions only, and call-in meetings and enforcements) on shootings in buffers around targeted gang territories. There were statistically significant reductions in shootings in half-mile buffers around gang territories matched to the timing of call-in meetings, and statistically significant reductions in shootings in half-mile buffers around gang territories matched to the timing of enforcements, but there were no statistically significant differences in shootings when matched to the timing of both call-in meetings and enforcements together. Roman and colleagues (2019) also examined the timing of the Philadelphia Focused Deterrence strategy on shootings only for gangs targeted by the strategy and found no statistically significant reductions in shootings attributed to the specific gangs subjected to the intervention.

These sources were used in the development of the program profile:

These sources were used in the development of the program profile:

Beccaria, Cesare. 1986. On Crimes and Punishment. Indianapolis, Ind.: Hackett.

Bentham, Jeremy. 1988. The Principles of Morals and Legislation. Amherst, N.Y.: Prometheus Books.

Hyatt, Jordan M., James A. Densley, and Caterina G. Roman. 2021. “Social Media and the Variable Impact of Violence Reduction Interventions: Reexamining Focused Deterrence in Philadelphia.” Social Sciences 10:147.

Nagin, Daniel S., and Greg Pogarsky. 2001. “Integrating Celerity, Impulsivity, and Extralegal Sanction Threats Into a Model of General Deterrence: Theory and Evidence.” Criminology 394:865–92.

Nagin, Daniel S., Robert M. Solow, and Cynthia Lum. 2015. “Deterrence, Criminal Opportunities, and Police.” Criminology 53(1):74—100.

Roman, Caterina G. 2021. “An Evaluator's Reflections and Lessons Learned About Gang Intervention Strategies: An Agenda for Research.” Journal of Aggression, Conflict and Peace Research, Special Issue: Reimagining Gang Research Without the Police, 13(2/3):148–67.

Roman, Caterina G., Megan Forney, Jordan M. Hyatt, Hannah J. Klein, and Nathan W. Link. 2020. “Law Enforcement Activities of Philadelphia’s Group Violence Intervention: An Examination of Arrest, Case Processing, and Probation Levers.” Police Quarterly 23(2):232–61.

Roman, Caterina G., Jordan M. Hyatt, Megan McConaghy, and Nathan L. Link. 2017. “Philadelphia Focused Deterrence Findings from the Impact Evaluation.” Philadelphia, Pa.: Temple University.

Braga, Anthony A., David M. Kennedy, Elin J. Waring, and Anne Morrison Piehl. 2001. “Problem-Oriented Policing, Deterrence, and Youth Violence: An Evaluation of Boston’s Operation Ceasefire.” Journal of Research in Crime and Delinquency 38(3):195–225.

Following are CrimeSolutions-rated programs that are related to this practice:

Focused Deterrence Strategies

This practice (also referred to as “pulling-levers policing”) includes problem-oriented policing strategies that follow the core principles of deterrence theory. The strategies target specific criminal behavior committed by a small number of individuals who chronically commit offenses, such as youth gang members or those who repeatedly commit violent offenses, who are vulnerable to sanctions and punishment. The practice is rated Promising for reducing crime.

Evidence Ratings for Outcomes

Crime & Delinquency - Multiple crime/offense types

Problem-Oriented Policing

These analytic methods are used by police to develop crime prevention and reduction strategies. The practice is rated Promising and led to a significant decline in crime and disorder.

Evidence Ratings for Outcomes

Crime & Delinquency - Multiple crime/offense types

Reducing Gun Violence

Reducing gun violence is a persistent public policy concern for communities, policymakers and leaders. To reduce gun violence, several strategies have been deployed including public health approaches (e.g., training and safe gun storage); gun buy-back programs; gun laws; and law enforcement strategies. The practice is rated Promising for reducing violent gun offenses.

Evidence Ratings for Outcomes

Crime & Delinquency - Violent offenses

Why might a practice's outcome ratings differ from the ratings of specific programs encompassed by that practice?