RALEIGH A federal judge has overturned the conviction of a North Carolina man sent to prison after he was wrongly charged as a felon for possessing firearms, the first of what could be thousands of inmates with similar convictions set aside.

Federal law makes it a crime for anyone with a felony record to have a gun. But because of an erroneous interpretation of North Carolina sentencing laws in place since 1994, federal prosecutors charged people with firearms possession even when their past offenses weren’t serious enough to qualify them as felons under federal law.

Senior U.S. District Judge James Fox on Thursday overturned the 2009 firearms conviction Terrell McCullum of Elizabethtown, declaring him innocent.

McCullum, 26, had already been released from prison in July after serving his full sentence, but he was still on probation.

Federal gun cases from North Carolina came under scrutiny after a U.S. Appeals Court ruled last year that prosecutors had been misapplying the law when it came to defining who is a felon. Even while conceding the affected inmates were “legally innocent” of the crimes for which they were convicted, federal prosecutors still argued in court for keeping McCullum and those like him behind bars.

That changed last Monday, when the government dropped its opposition to releasing those improperly convicted of firearms possession when it was not illegal for them to have guns.

“After careful consideration, the Department of Justice has decided to take a litigating position designed to accelerate relief for defendants in these cases who, by virtue of a subsequent court decision, are no longer guilty of a federal crime,” said Justice Department spokeswoman Adora Andy. “We are working with the court, the probation office and the federal public defenders to ensure that these matters are addressed as effectively and quickly as possible.”

Andy said prosecutors haven’t yet determined how many people in prison could eventually be released. Reviews by federal public defenders in North Carolina and the USA Today newspaper identified more than 60 inmates whose circumstances are similar to McCullum, several of whom already have appeals pending.

A preliminary review conducted by the American Civil Liberties Union of North Carolina found more than 3,000 federal prisoners who are potentially innocent or entitled to reduced sentences.

“This is an encouraging first step, but much more has to be done to obtain justice for those who were wrongly incarcerated,” said Chris Brook, Legal Director of the ACLU of North Carolina Legal Foundation. “We continue to urge the Justice Department to take a proactive stance toward identifying and assisting all those who may be unjustly languishing in prison.”