In fractious Washington, there are very few policy reforms that command bipartisan support. One of them is the result of an emerging consensus that America’s criminal justice system is badly broken.

Statistics tell part of the story. The United States has 5 percent of world’s population but houses 25 percent of its prisoners. Its federal prison population has more than quadrupled since 1980, to 2.3 million souls. Prisons and criminal justice agencies combined cost taxpayers $260 billion a year.