Last week, Attorney General Jeff Sessions retracted an Obama-era guidance to state courts that was meant to end debtors’ prisons, where people who are too poor to pay fines are sent. This practice is blatantly unconstitutional, and the guidance had helped jump-start reform around the country. Its withdrawal is the latest sign that the federal government is retreating from protecting civil rights for the most vulnerable among us.

The Justice Department helped shine a light on the harms of fine and fees when it investigated Ferguson, Mo., three years ago after the killing of the teenager Michael Brown by a police officer. As one of the lawyers on that case, I saw firsthand the damage that the city had wrought on its black community.

Ferguson used its criminal justice system as a for-profit enterprise, extracting millions from its poorest citizens. Internal emails revealed the head of finance directing policing strategy to maximize revenue rather than ensure public safety. Officers told us they were pressured to issue as many tickets as possible.

Even the local judge was in on it, imposing penalties of $302 for jaywalking and $531 for allowing weeds to grow in one’s yard. He issued arrest warrants for residents who fell behind on payments — including a 67-year-old woman who had been fined for a trash-removal violation — without inquiring whether they even had the ability to pay the exorbitant amounts. The arrests resulted in new charges, more fees and the suspension of driver’s licenses. These burdens fell disproportionately on African-Americans.