WASHINGTON (CNN) -- The U.S. Department of Justice has filed court documents signaling an end to its efforts to block the release of a number of federal prisoners who it concedes are "legally innocent" following an appeals court ruling last year.

The Justice Department has not publicly identified the inmates who could be eligible for release or shortened sentences. The American Civil Liberties Union in North Carolina, where the government filed its "reconsidered" position, urged Justice lawyers to promptly identify inmates who could be affected by the appeals court ruling.

In the North Carolina case, defendants had challenged their sentences for gun possession, arguing that the federal courts wrongly considered them felons because a state law set maximum sentences based on the extent of a defendant's criminal record. Defendants with prior criminal records, when convicted of crimes that ordinarily would result in sentences of less than a year in prison, could get terms of more than a year.

The 4th Circuit Court of Appeals ruled that to be sentenced as a felon for gun possession, a defendant had to have been convicted of a crime for which the sentence could have been more than one year regardless of criminal history.

The ACLU said it believes as many as 3,000 defendants were prosecuted under North Carolina's law over the past 15-20 years, but many of them may have already served their time and been released. USA Today, which had first investigated the issue, said it had identified as many as 60 prisoners who could be affected by the appeals court ruling.

Justice took the action "to accelerate relief for defendants in these cases, who by virtue of a subsequent court decision, are no longer guilty of a federal crime," spokeswoman Adora Andy said in a brief written statement.

Lawyers familiar with the cases said most if not all of these now "innocent" prisoners were prosecuted in North Carolina; it was not clear whether there are inmates in other states who would be affected.