"No one truly knows a nation until one has been inside its jails,” Nelson Mandela once said—and who should know better?—except perhaps Dostoevsky, who said the same thing a century earlier. By that standard, the justice system of the United States, with more people behind bars than any other country in the world, doesn’t even measure up to the society under which Mandela lived, which in 1993 locked up its citizens at a rate of 368 per 100,000, compared to 655 in the U.S. as of 2016. The U.S. even imprisons black men at a higher rate than South Africa did under apartheid.

But the number of Americans in jails and prisons—around 2.2 million—is now at a 20-year low and still falling, as crime declines and the FIRST STEP Act, signed by President Trump in December, has cracked open the door to parole for victims of the mandatory minimum sentencing laws passed in the 1990s. But the law only benefits people convicted of federal crimes; 90 percent of American prisoners are held in state prisons and local jails. Parallel efforts are under way in many states, including New York, where a report by a commission headed by former chief judge Jonathan Lippman has recommended reforms, including as a “top priority” ending cash bail. “Almost a third of the people admitted to jail are released within four days, suggesting that many should not have been jailed at all,” Lippman wrote.