Bipartisan efforts to change the criminal justice system have gained momentum around the country in recent years. Nearly all 50 states, many counties, and the federal government have sought to reduce imprisonment and mitigate its harms. A remarkable wave of legislation has shortened custodial sentences and widened eligibility for sentences served in the community. States and localities have also invested in rehabilitation and reentry services.Yet the impact of these efforts has been relatively modest. While the nation's imprisoned population has declined since peaking in 2009, incarceration levels remain extraordinarily high. Nearly 1.2 million people are serving sentences in state and federal prisons, and 10.3 million are admitted to loc...