Research at the DAO

The DATA Lab at the Philadelphia District Attorney’s Office (DAO) uses police, court, and other data streams to support a wide range of research on the criminal legal system. We work with external partners across all phases of the research arc to help develop impactful interventions, evaluations, and scholarship. This includes discussions around data sharing, data use agreements, and facilitating research involving Assistant District Attorneys (ADAs) and DAO personnel.

The DAO DATA Lab was created by District Attorney Krasner to help the Philadelphia District Attorney’s Office and the criminal legal system end the era of mass incarceration and mass supervision, and to ensure transparency and accountability while doing so. During a time of rapid change in the criminal legal system, the DATA Lab supports research that aligns with the following principles:

  • Provide external evaluation of DAO decisions, processes, and policies
  • Investigate racism, sexism, classism, and other systemic disparities in the criminal legal system
  • Involve and center communities most impacted by criminal legal system
  • Improve the day-to-day functioning of the DAO (e.g., training, case processing, work product)
  • Offer potential long-term benefits to DAO (e.g., process, maps, reports, code)
  • Complement DAO resources and helping to better understand social problems and the role of DAO
  • Address research questions of immediate interest or specific need and help fill gaps in social science research
  • Work with investigators who are subject-matter experts on topic(s) of inquiry

Following are DAO DATA Lab grant-funded partnerships, publications based on work supported by the DAO, and ongoing studies with research partners. If you are interested in submitting a research proposal or potentially collaborating with the DATA Lab, please complete this form. If you have any comments or questions, please email Director of Research Oren Gur, PhD ().

Grant-Funded Partnerships

A researchable prosecutorial office in the criminal justice reform era: A partnership with the University of Pennsylvania and Temple University supported by Arnold Ventures and the Chan Zuckerberg Initiative

Researchers: Greg Ridgeway, Aurélie Ouss, David Abrams, Aaron Chalfin, Paul Heaton, Charles Loeffler, Francesca Amaral, Miguel Garza-Casado, Viet Nguyen, Lee Ozier, Lindsay Graef, Julia Reinhold (University of Pennsylvania). Peter Jones, Jeffrey T. Ward, E. Rely Vîlcică, Caterina G. Roman, Cathryn Rosen, Cheryl Irons, Doris Weiland (Temple University)
Press Release

The DATA Lab and DAO are working with independent researchers at the University of Pennsylvania and Temple University to investigate the impacts of ADA discretionary decision-making and prosecutor-led criminal legal reform. Funded by the largest research grant in the history of the DAO, this private-public collaboration with local universities aims to study the short- and long-term impacts of prosecutorial decision-making on individuals, families, and communities in Philadelphia.

$4.5M over 3 years to DAO, $2.2M over 3 years to Penn Criminology and Temple Criminal Justice

Research partners from Penn’s Department of Criminology will focus on the quantitative impacts of reforms on a broad scope of prosecutor touchpoints, while research partners from Temple University’s Department of Criminal Justice will utilize mixed methods to study the implementation fidelity of new policies and practices.

This unique partnership will:
  • Improve existing data systems and bolster the DAO’s data analytics and programming capacity
  • Establish a local and national hub for research on prosecutorial decision-making, data-informed policy, and analytical innovations
  • Investigate racial and other disparities in the criminal legal system
  • Consider the relationship between criminal legal system contact and broader outcomes related to social and economic health
  • Engage with DAO personnel and actors across Philadelphia’s criminal legal system
  • Examine the efficiency and effectiveness of policy and programmatic changes made within the DAO
  • Provide accountability and transparency both internally and to the public


Investigating long-term outcomes of Focused Deterrence and Cure Violence in Philadelphia: A partnership with Temple University supported by the Fund for a Safer Future.

Researchers: Caterina Roman, Nicole Johnson (Temple University). Kevin Wolff (CUNY John Jay College)

A follow-up study to better understand unanticipated and longer-term impact of gun violence prevention programs implemented in Philadelphia in the last decade.

∼$100k to DAO, ∼$100k to Temple/John Jay

In the last decade the City of Philadelphia has implemented two of the most well-known community-level gun violence strategies in the US: the Cure Violence Public Health Model and Focused Deterrence (also known as Group Violence Intervention). This project builds on prior research on these topics to answer the following research questions:

(1) For Focused Deterrence, how does the specific deterrence aspect of arrest and incarceration compare to those arrested/sentenced under business-as usual conditions (individuals in the comparison group arrested during the same period from other parts of the city)?
(2) How do the interventions differentially influence clearance rates over time (defined as shootings cleared by arrest-to-prosecution)?
(3) Did the density / concentration of shootings in census tracts with 2013 shooting hotspots change between 2013 and 2017? Have new hotspots emerged?

Changes also will be assessed against other shooting hotspots from neighborhoods without evidence-based interventions in 2013. This study fills a gap in the literature by exploring the application of “specific deterrence” and the impact of the actual legal punishment on those who are apprehended. We will also advance the evaluation literature by examining the impact on clearance rates and long-term outcomes for individuals and communities.


DAO Publications

100 Shooting Review Committee Report

Report Press Release View DAO Excerpts

A report on increased gun violence, homicide, and access to firearms in the City of Philadelphia co-authored by the DAO, Philadelphia Police Department, Department of Public Health, and Defender Association.

Firearm violence in Philadelphia is a public health and racial justice crisis. In this report agencies provide analyses and recommendations on how to address the increase in homicides, shootings, and access to firearms in Philadelphia. Collectively, we present 16 key findings and 27 recommendations. Key findings focus on what we know about shootings, including information on arrest and case processing. Recommendations identify opportunities to improve enforcement, intervention, and prevention. In addition, the DAO, led by the District Attorney’s Transparency Analytics (DATA) Lab, offer in-depth analyses on 1) improving shooting clearance rates, 2) improving gun case outcomes, 3) deterrence of illegal firearm possession, and 4) improving victim and witness appearance rates. We then offer recommendations on those same themes, and on preventing gun violence in the community more holistically. This report offers a framework, findings, and recommendations, but does not constitute a comprehensive plan; we hope it can help inform a broad citywide strategy to address gun violence through law enforcement and much more.


Ending mass supervision: Evaluating reforms in the Philadelphia District Attorney’s Office

Report Press Release

An assessment documenting reductions in community supervision lengths under two DAO policies. Racial disparities in sentencing decreased and the reforms were implemented without increases in re-charge rates.

Abstract: Probation and parole – commonly called community supervision – can be less restrictive alternatives to incarceration, but overly lengthy supervision terms are harmful to the defendant and to public safety. Community supervision rates in Pennsylvania and Philadelphia are particularly high: at the beginning of District Attorney Krasner’s term, 1 in 23 adults in Philadelphia was on community supervision. This evaluation documents two policies to end mass supervision that were implemented in the Philadelphia District Attorney’s Office. Under the policies, median supervision lengths decreased by 12 months (a 25% reduction) for felony negotiated guilty pleas and 3 months (a 33% reduction) for misdemeanor negotiated pleas. Prior to the policy changes, white defendants received supervision sentences that were almost 11 months shorter than Black defendants’, on average. The policy reduced the disparity to 5.2 months, a more-than-50% reduction. The policies were implemented without an increase in recidivism: there was no measurable change in re-charge rates between people sentenced under the policies and those sentenced beforehand. The DAO has made progress, but collaboration by all system actors and lawmakers across the Commonwealth is necessary to end mass supervision in Pennsylvania.


Prosecutor-led bail reform: Year one

Report Press Release

A DAO evaluation of bail reform implemented by the DAO in 2018 showing that the policy reduced the use of cash bail without impacting recidivism or court appearance rates. The wide-ranging policy applied to over three in five charges, allowing approximately 1,750 additional Philadelphians to be released without cash bail in 2018, and was implemented at no cost. (See Ouss and Stevenson in Published Studies for more).

Abstract: The use of cash bail and pretrial detention disproportionately impacts people living in poverty and people of color, influencing the trajectory of legal cases, and is a driver of mass incarceration. Fifty days into DA Krasner’s administration, the Philadelphia DAO implemented a new policy targeting 25 charges where an analysis of historical data showed the courts had been setting bail very low—requiring payment of less than $1,000. For these specific charges, a presumption was created to not request cash bail. As a result, the release on recognizance rate for eligible charges increased from 83% pre-policy to 90% post-policy for misdemeanors, and from 24% pre-policy to 32% post-policy for felonies. We observed a continued upward trend in the likelihood that someone would fail to appear in court at least once, but no increase in pre-trial re-arrest rates for either misdemeanors or felonies targeted by the bail policy. Overall the policy and evaluation demonstrate that more people can safely be released during the pretrial period, offering broad social benefits to individuals and communities while reducing unnecessary burdens on the criminal legal system.


Overturning Convictions–and an Era: Conviction Integrity Unit Report January 2018 - June 2021

Report Press Release

A report detailing the work of the Conviction Integrity Unit from January 2018 through June 2021. The report encompasses exonerations, commutations, sentencing adjustments, active investigations, cases declined or closed, and cases awaiting review. It highlights the 20 individuals exonerated in this time period, all but one of the which occurred because of official misconduct committed by prosecutors and/or police, such as withholding exculpatory evidence, coercing false confessions, or committing perjury.

Abstract: Our sworn oath as prosecutors is to seek justice unconditionally, with no limit as to time. When we discover past injustices, we must not only right those wrongs, but implement policies to ensure that they do not occur again in the future. This report describes how an independent Conviction Integrity Unit, with a broad mandate, has worked to change the culture and practices of the District Attorney’s Office. Our oath requires that we never stop trying to fix injustices, even if they turn out to be the product of our administration’s missteps. During court proceedings involving defendants the CIU has determined to be innocent of the crimes for which they were wrongly convicted, the District Attorney’s Office as an institution has apologized to the exonerees. We should. Lost years and decades of a life cannot be returned. But we remain enormously proud of what we have done to date.


Published Studies

Exploring Prosecutorial Discretion in the Plea Bargaining Process: A partnership with the Urban Institute supported by the John D. and Catherine T. MacArthur Foundation’s Safety & Justice Challenge

Researchers: Andreea Matei, Kelly Freeman, Lily Robin, and Leigh Courtney
Full Report Webinar Data Story Press Release

A mixed-methods exploration of how policies, discretion, and long-time criminal justice conventions impact fairness in plea outcomes in Philadelphia.

Abstract: There has been a lack of research concerning plea bargaining despite the fact that 97 percent of federal convictions and 94 percent of state convictions are the result of guilty pleas. With support from the MacArthur Foundation’s Safety and Justice Challenge (SJC), Urban Institute partnered with the Philadelphia District Attorney’s Office to conduct mixed-methods research to better understand the plea-bargaining process. This study aimed to investigate the many factors that can influence the decision making of Assistant District Attorneys (ADAs), which in turn influences case outcomes. Researchers surveyed ADAs and conducted interviews of defense providers, prosecutors, and individuals who previously accepted pleas in Philadelphia. A review of policies, administrative data, and supplemental case file data also informed this work.

The Urban Institute’s findings suggest that the Pennsylvania Sentencing Guidelines as well as the “trial penalty” (longer sentences for those found guilty at trial versus those who accept offers) may act as mechanisms that exacerbate racial disparities and mass incarceration, respectively. They also note that there is more work to do both locally and nationwide in order to obtain better data on plea bargaining, and to better understand its role in the criminal legal system.


The efficacy of prosecutor-led, adult diversion for misdemeanor offenses

Researchers: Viet Nyugen (University of Pennsylvania Criminology)
Paper Brief Summary Press Release

An evaluation of the Accelerated Misdemeanor Program (AMP) to quantify the effect of diversion on recidivism outcomes, future fees, future sanction time, and expungement rates.

Abstract: The DATA Lab collaborated with Viet Nguyen of Penn Criminology to evaluate the Accelerated Misdemeanor Program (AMP), a diversion program initiated in 2010. The program offers opportunity for expungement to non-violent misdemeanor offenders with no prior convictions in the previous 10 years after completion of a community service sentence and payment of associated court fees. AMP’s objective is to move away from creating criminal records for low-level offenses, which can prevent access to pro-social institutions like education, employment, and familial activities. This study analyzes AMP’s impact on long-term recidivism outcomes and the future amount of court-imposed fees and sanctions, as well as exploring the programs effect on dismissals and expungements.


Correctional “Free Lunch”? Cost Neglect Increases Punishment in Prosecutors

Researchers: Eyal Aharoni (Georgia State University), Heather M. Kleider-Offutt (Georgia State University) and Sarah F. Brosnan (Georgia State University)

National survey of prosecutors to better understand how insulation from sentencing costs influences sentencing recommendations.

Abstract: Prosecutors can influence judges’ sentencing decisions by the sentencing recommendations they make—but prosecutors are insulated from the costs of those sentences, which critics have described as a correctional “free lunch.” In a nationally distributed survey experiment, we show that when a sample of (n=178) professional prosecutors were insulated from sentencing cost information, their prison sentence recommendations were nearly one-third lengthier than sentences rendered following exposure to direct cost information. Exposure to a fiscally equivalent benefit of incarceration did not impact sentencing recommendations, as predicted. This pattern suggests that prosecutors implicitly value incorporating sentencing costs but selectively neglect them unless they are made explicit. These findings highlight a likely but previously unrecognized contributor to mass incarceration and identify a potential way to remediate it.


Crisis Assistance, Response & Engagement for Survivors of Homicide: C.A.R.E.S. Highlights and process evaluation 2020-2021

Researchers: Kate Kelly (Temple University), Caterina G. Roman (Temple University), Rely E. Vîlcică (Temple University), Jordan M. Hyatt (Drexel University), Danielle T. Stanford (Temple University)
Highlights Report Highlights Report Slideshow Process Report

Highlights and process evaluation of the new Crisis Assistance, Response & Engagement for Survivors (CARES) program in the Philadelphia District Attorney’s Office.

Abstract: Crisis Assistance, Response & Engagement for Survivors (CARES) provides crisis response and service connections for those who have lost loved ones to homicide. CARES, which began providing services in 2019, is housed in the Philadelphia District Attorney’s Office (DAO) and funded by the Pennsylvania Commission on Crime and Delinquency (PCCD). What makes CARES uniquely effective is that all of their staff have lived experience – they know what it’s like to lose someone to homicide. The first document — available in PDF and as a slideshow — provides highlights of CARES, while the second document offers a more detailed process evaluation that will help improve the program and can serve as a roadmap for other jurisdictions to adopt the CARES model. This PCCD-funded process evaluation was conducted between 2019 and 2021 by researchers in the Temple University Department of Criminal Justice with assistance from faculty at Drexel University. A journal article co-written by CARES staff and Temple researchers is currently under production and will be posted when available.


Resentencing of juvenile lifers: The Philadelphia experience

Researchers: Tarika Daftary-Kapur (Montclair State University), Tina Zottoli (Montclair State University)
Working Paper on Resentencing Press Release on Resentencing Video on Reentry Working Paper on Reentry

First report on resentencing illuminated the cost savings and low recidivism rates associated with juvenile lifers from Philadelphia who were resentenced following a recent U.S. Supreme Court decision and released. The second report focuses on life prior to, during, and after incarceration for former juvenile lifers, including issues pertaining to employment, housing, and social relationships.

In the 2020 report we examined the Philadelphia District Attorney Office’s approach to juvenile lifer resentencing, which began in 2017 under the administration of District Attorney Williams and has continued under the administration of District Attorney Krasner. For 174 cases resentenced as of December 31st, 2019, we describe similarities and differences between the Williams and Krasner administrations in decision making and sentence length reductions, and report on the recidivism rate and estimated cost savings for Pennsylvania as a result of release. Philadelphia’s experience also shows that when this review process leads to release, successful reintegration is not just possible, but is the most likely outcome (as evidenced by negligible recidivism rates, 1.14% reconviction rate). These releases also come with substantial cost savings, an estimated $9.5M in correctional costs for Pennsylvania over the first decade, just for the 174 juvenile lifers released. Considering that the overwhelming majority of individuals who commit crime—even serious crime—“age out” of criminal behavior, the societal, financial, and public safety benefits of continued incarceration of those serving lengthy sentences is called into question by the Philadelphia experience.

In the 2022 report, we present findings from a survey of 112 individuals from Philadelphia, Pennsylvania who were sentenced to life without the possibility of parole for crimes committed in their youth (I.e., “juvenile lifers,”) and were subsequently released. Findings include that, for example, respondents with more early risk factors experienced more challenges across all categories of reentry, with the largest associations for securing employment and reconnecting with family. This is the first time such a large concentration of individuals sentenced to life for violent offenses (in this case, homicide) have been released, providing us with the unique opportunity to (1) examine whether their reentry experiences are consistent with existing data on prisoner reentry, and (2) update and inform evidence-based policies on how we can best prepare for, and support, returning citizens who have served long sentences.


Bail, jail, and pretrial misconduct: The influence of prosecutors

Researchers: Aurélie Ouss, (University of Pennsylvania), Megan T. Stevenson (University of Virginia School of Law)
Working Paper Press Release

An evaluation showing that 2018 bail reform led by the DAO successfully increased the number of people released without having to pay cash bail while not increasing pretrial misconduct or decreasing court appearance rates.

Abstract: Dozens of jurisdictions across the country are engaging in bail reform, but there are concerns that reducing monetary incentives will increase pretrial misconduct. We provide new evidence on this question by evaluating a prosecutor-led bail reform in Philadelphia. In February 2018, Philadelphia’s district attorney announced that his office would no longer request monetary bail for defendants charged with certain eligible offenses. This was an advisory change; bail magistrates retained final say. Using a difference-in-differences approach we find that this policy led to a 22% increase in the likelihood a defendant will be released with no monetary or supervisory conditions, but had no impact on pretrial detention. This provides a unique opportunity to evaluate the primary justification for cash bail: that it provides incentive for released defendants to appear in court. We find no evidence that cash bail or pretrial supervision has a deterrent effect on failure-to-appear or pretrial crime. We argue that one explanation is that asymmetric reputational penalties cause magistrates to set bail higher than necessary. In addition, our study provides evidence on the role of discretion within criminal justice reform. We find that discretion led to racial disparities in implementation, and diluted the impacts of the reform.


Missed opportunities: Arrest and court touchpoints for individuals who fatally overdosed in Philadelphia in 2016

Researchers: Ruth T. Shefner (Columbia University), Jason S. Sloan (University of Pennsylvania), Kayla R. Sandler (University of Pennsylvania), Evan D. Anderson (University of Pennsylvania)
Peer-Reviewed Paper

This study describes how often people who fatally overdosed in Philadelphia in 2016 interacted with the criminal legal system throughout their life, including how their criminal history may have made them ineligible for diversion programs. These contact points are framed as missed opportunities to help people.

Abstract: Many studies document high risk of fatal overdose after incarceration. Few explore earlier touchpoints in criminal justice processes, like arrests and court hearings. Understanding these touchpoints is important for several reasons. Arrest and adjudicatory processes are harmful even when not resulting in incarceration. Arrests and criminal hearings also may reflect changes in overdose-related risk factors like transitions in employment and housing stability. Moreover, knowledge about these touchpoints contextualizes debate about the implementation of court-based programs like Drug Treatment Courts. This study described the incidence and accumulation of touchpoints for people who fatally overdosed in Philadelphia in 2016, and depicted how touchpoint incidence and characteristics interface with court-program eligibility.

In 2016, 907 people fatally overdosed in Philadelphia. Of these, 605 had at least one or more of 3,926 arrests and 3,822 hearings over their lifetime. There were 488 arrests and 533 hearings in the two years before death, with public disorder charges especially common closer to death. Less than 20% of these hearings resulted in custodial sentences. Of individuals with touchpoints, only nine participated in Drug Treatment Court, consistent with findings that most individuals were ineligible. Latent class analysis suggested five distinguishable patterns in age, timing, and characteristics of touchpoints.

The type and frequency of touchpoints preceding fatal overdose reflect a period of complex vulnerability. Few individuals qualified for court-based programming, underscoring the limitations of supporting this population in specialized court settings. Reducing incidence and improving the health impact of criminal justice touchpoints remain important public health priorities.


Ongoing Studies

Testing the Impact of a Drug Testing Backlog on Sentencing and Case Outcomes

Researchers: Miguel Garza Casado (University of Pennsylvania), Oren Gur (DATA Lab), and Sebastian Hoyos-Torres (DATA Lab)

The goal of this study is to measure the effects of a drug-testing backlog on case and defendant outcomes. It takes advantage of a natural experiment created by a policy change adopted to address the drug-testing backlog in August 2019 by the Philadelphia Police Department (PPD) Office of Forensic Science (OFS) and the Philadelphia District Attorney’s Office (DAO).

This project focuses on the implications of a drug-testing backlog for defendant and case outcomes, considering whether the backlog led to higher case declination rates. In Philadelphia, a backlog of between 5,000 and 10,000 cases requiring drug testing developed over the years, with approximately 1,000 to 2,000 new submissions each month. In August 2019, the Philadelphia Police Department (PPD) Office of Forensic Science (OFS) and the District Attorney’s Office (DAO) implemented a policy change to address this drug testing backlog. The implementation of this policy creates a natural experiment that can be used to compare, and better understand, the outcomes of defendants whose samples were not tested during the backlog relative to those whose samples were successfully tested.


Understanding the impact of body worn cameras on prosecutorial outcomes

Researchers: Amanda Agan (Rutgers University), Danielle Li (MIT Sloan School of Management), Liz Groff (Temple University)
Relevant Reading

This study examines how the availability of body worn camera (BWC) footage impacts criminal cases as they move through the legal system. It will look at how the presence of BWC footage affects the types of charges brought, conviction rates, and sentencing outcomes, as well as how these effects may vary based on attributes like arrestee race and prior convictions.

Abstract: New technological advances are rapidly impacting the type of evidence available in criminal cases. This includes advances in DNA technology, fingerprint detection, and the existence and usage of body-worn camera (BWC) footage, amongst others. This study is broadly interested in understanding whether the use and interpretation of such technologically-aided evidence impacts prosecutorial decisions, conviction, and sentencing outcomes, and how these impacts differ across groups.


Minor charges with major impacts: Understanding the use of select misdemeanors among persons with serious mental illnesses

Researchers: Jen Wood (Temple University), Michael Compton (Columbia University), Leah Pope (Vera Institute of Justice), Amy Watson (University of Wisconsin-Milwaukee)

The goal of this study is to gain an in-depth understanding of the use and processing of misdemeanor charges that are historically common among individuals with serious mental illnesses.

Abstract: Approximately one million arrests per year in the United States involve persons with serious mental illnesses (SMI), and such individuals are over-represented across all facets of the criminal justice system. Research to date has shown that it is misdemeanor charges that are often used to address behaviors associated with manifestations of illness (e.g., a person with disorganized thinking and disorganized behavior stemming from schizophrenia could be charged with disorderly conduct or another public nuisance misdemeanor), or stem from the circumstances in which persons with SMI find themselves (e.g., a person with limited financial resources and homelessness could be charged with criminal trespass, loitering, panhandling, or other misdemeanor charges). However, remarkably little research has been done to describe and explain the exact nature of the applied misdemeanor charges. This includes the underlying logic(s) for applying such charges in the face of limited alternatives, as well as how such charges move through different stages of criminal justice decision-making, beginning with officers on the street. By deepening our knowledge of the nature, use and processing of select misdemeanor charges, the findings of this study should inform current research and policy efforts in Philadelphia and elsewhere centered on alternative approaches to the handling of mental health-related incidents. This study has a 4-site comparative focus – Atlanta, Philadelphia, New York, and Chicago.


Study on the effects of automatic sealing of cases on recidivism and economic outcomes

Researchers: Amanda Agan (Rutgers University), Andrew Garin (University of Illinois Urbana-Champaign), Dmitri Koustas (University of Chicago), Alexandre Mas (Princeton University), Crystal Yang (Harvard Law School)

This project aims to evaluate the short- and long-term benefits to individuals who have had their criminal record automatically sealed under Pennsylvania’s Clean Slate Law.

This study will include an evaluation of Pennsylvania’s Clean Slate law, pioneering legislation mandating the automatic sealing of eligible criminal records, rather than relying on a petition-based system as Pennsylvania used to do (and most jurisdictions still do). The evaluation would seek to understand how the sealing automatically undertaken through the Clean Slate law impacts economic and criminal justice outcomes for affected defendants.