A study of 118 exonerated inmates led by Evan Mandery and Amy Shlosberg, two criminal-justice researchers, found that one-third still had criminal records, sometimes more than a decade after their release. They found that former convicts with clean records were less likely to return to prison than those whose records had not been expunged.

Some states, including New York and Illinois, have a straightforward process for erasing or sealing criminal records after a wrongful conviction. But legal researchers say that most state laws are out of date with the recent waves of exonerations, and require onetime convicts already declared not guilty to once again prove their innocence.

“Even in the best case, it is difficult to move beyond a prison sentence,” Mr. Mandery and Ms. Shlosberg wrote in their study, which is now under review at The Journal of Criminal Law and Criminology. “The wrongful conviction serves as a permanent, undeserved stigma.”

Of course, blotting out a criminal record does not solve everything. Researchers have found that high percentages of the wrongfully convicted slide into poverty or substance abuse as they struggle to rebuild a life outside prison. How do you explain a 10-year gap on a résumé? How do you answer a yes-or-no question from a prospective employer asking whether you have ever been convicted of a felony?

“Employers, if they see a homicide conviction, dismissed or not, they’re not going to get past that,” said Saundra Westervelt, an associate professor of sociology at the University of North Carolina at Greensboro, who has written extensively about exonerated death-row inmates. “The conviction is still there. You’re stuck.”

In Alabama, Gary Wayne Drinkard said he was pulled over for a routine traffic stop after being released from prison. His 1995 murder conviction had been overturned, and a second jury trial found him not guilty. But, he said, the charges popped up when the officer ran a background check. Mr. Drinkard said he was held in the squad car for 30 minutes while the police checked out his story.