Prosecutors have one big reason to protect harsh sentencing: Today, around 95 percent of federal and state criminal cases end in a plea bargain. Such agreements, in which the defendant pleads guilty in exchange for a fixed sentence, avoid the time and expense of a jury trial, making it faster and cheaper for prosecutors to close cases. And the more draconian the punishments that a prosecutor has at her disposal—high mandatory minimums, say, or the ability to charge a youthful offender as an adult—the more leverage she has to persuade someone to take a plea bargain instead of risking a trial.

In the last year or so, criminal-justice reform has topped the legislative agenda in several states, from conservative Florida and Louisiana to liberal California, and advocates for reform exist across the political spectrum, from the conservative Right on Crime, the Koch brothers, and former House speaker Newt Gingrich to the ACLU and Black Lives Matter. In response, prosecutors’ associations have pushed legislators hard to reject such reforms. And, in most cases, they have succeeded.