When I first met Malaki Mathieson last winter, he was desperately trying to find work. Mathieson, then 27, had been going to business school before he went to prison. When he got out, he went on job interviews. When the question about criminal history inevitably came up, he tried to stress to potential employers that he’d changed. But they still wanted to know about his conviction, and why he’d been in prison. It usually turned out badly.

“I told her about my conviction, and she wanted me to go deeper into what happened,” he told me, describing one interview in particular. “When I explained that I shot somebody in the back of the head, she didn’t want anything to do with me anymore.”

So-called ban-the-box policies—which prevent employers from asking about a candidate’s criminal history until later on in the hiring process—aim to help people like Mathieson more easily enter the labor market. President Obama “banned the box” on federal-government employment applications last year, and as of December 2015, 24 states and the District of Columbia have required employers to ban the box in some form.

But banning the box may actually be hurting some of the exact groups of people it was designed to help, according to a few new studies. In a recent paper from the National Bureau of Economic Research, Jennifer L. Doleac of the University of Virginia's Frank Batten School of Leadership and Public Policy and Benjamin Hansen of the University of Oregon looked at how the implementation of ban-the-box policies affected the probability of employment for young, low-skilled, black and Hispanic men. They found that ban-the-box policies decreased the probability of being employed by 5.1 percent for young, low-skilled black men, and 2.9 percent for young, low-skilled Hispanic men.