Criminal Justice Reform: What Research Shows About Incarceration and Alternatives

The United States has the highest incarceration rate in the world, housing roughly two million people in federal prisons, state prisons, and local jails on any given day. This represents a fourfold increase from 1980, driven by policy choices including mandatory minimum sentencing, truth-in-sentencing laws, three-strikes provisions, and the expansion of criminally sanctioned behaviors during the war on drugs. Research on the consequences of this expansion, for individuals, families, communities, and the broader society, and on the effectiveness of reform approaches, has grown substantially and informs a policy debate that has found unusual bipartisan attention. The deterrent effect of incarceration is the central claim advanced in justification of punitive criminal justice policies. The logic holds that longer sentences and higher certainty of imprisonment will cause potential offenders to recalculate the expected costs and benefits of crime and choose not to commit it. Research on specific deterrence, the effect of incarceration on the future behavior of those who are incarcerated, finds weak and generally negative effects: individuals who are incarcerated are more likely, not less, to commit crimes after release than comparable individuals who receive alternative sanctions. Research on general deterrence, the effect of punishment on the broader population, finds that the certainty of punishment deters crime more than its severity, suggesting that extending sentence lengths produces little additional deterrent effect at enormous financial and human cost. The consequences of incarceration for individuals are well-documented. Prison disrupts employment histories, family relationships, housing stability, and access to public benefits. Research on employment outcomes for formerly incarcerated individuals finds persistent wage penalties, high unemployment, and concentration in informal and low-wage work. These outcomes reflect both employer discrimination, which research documents as pervasive, and the disruption of social networks and work experience that employment depends on. Studies of formerly incarcerated individuals in various states find that criminal record check-box requirements on job applications substantially reduce callback rates, a finding that has motivated ban-the-box policies in many jurisdictions. The consequences of parental incarceration for children are severe and well-researched. Children with incarcerated parents show elevated rates of behavioral problems, educational difficulties, and emotional distress. Research on intergenerational effects finds that parental incarceration increases children's own risk of future criminal justice system involvement, suggesting that punitive approaches to crime produce cycles of involvement across generations rather than breaking them. Racial disparities in incarceration are among the most documented features of the American criminal justice system. Black Americans are incarcerated at rates roughly five times higher than white Americans for similar offenses. Research using audit studies, analyses of administrative data, and qualitative investigation has documented racial disparities at multiple decision points in the criminal justice process, including stops, arrests, charging decisions, bail determinations, plea offers, sentencing, and parole. These disparities are not fully explained by differences in criminal behavior or prior records and reflect the operation of implicit bias and structural factors throughout the system. Reform approaches that have received significant research attention include diversion programs, drug courts, community supervision alternatives to incarceration, and reentry support programs. Drug courts, which divert individuals with substance use disorders from traditional prosecution to treatment-focused supervision, have been among the most extensively evaluated reform approaches. Meta-analyses find that drug courts reduce recidivism compared to traditional prosecution, with the strongest effects for programs that prioritize treatment over punitive sanctions. However, the evidence is stronger for some populations than others, and concerns about net-widening, drawing more people into formal supervision than would otherwise have been involved, complicate the picture. Pretrial detention is a dimension of the criminal justice system that receives growing attention. Research finds that detained defendants are more likely to be convicted, to receive custodial sentences, and to lose employment than comparable defendants who are released pending trial. These effects appear to be causal rather than merely reflecting differences between defendants who are detained and those who are released. Cash bail, which conditions release on the ability to pay, has been criticized as a system that punishes poverty rather than assessing risk, and several states have moved toward risk-based release assessments. Reentry support programs that address the practical challenges of returning to community life after incarceration have demonstrated effectiveness in some rigorous evaluations. Employment programs that provide transitional jobs have shown mixed results, with some studies finding significant reductions in recidivism and others finding smaller effects. Housing assistance for individuals released from incarceration reduces the risk of homelessness and its associated instability. Cognitive-behavioral programs that address criminal thinking patterns have shown moderate effects on recidivism in several meta-analyses. The evidence base for criminal justice reform has grown sufficient to inform policy choices about which approaches are most likely to reduce crime while reducing the human and financial costs of mass incarceration. The research suggests that certainty rather than severity of consequences deters crime, that incarceration produces more harm than deterrence for individuals and communities at current scale, and that community-based alternatives can address public safety at lower cost to individuals and society.