WASHINGTON — U.S. Attorney General Eric Holder said Wednesday that some prisoners incarcerated for crack cocaine offenses should benefit from a new law that lowers crack sentences.

Holder was testifying before the U.S. Sentencing Commission, which oversees the guidelines that help federal judges sentence offenders.

The commission is considering making a change that would reduce the sentence of some inmates previously incarcerated on crack offenses by an average of three years. The change could bring earlier release for as many as one out of every 18 federal prisoners, or approximately 12,000 inmates.

In the eastern district of Virginia, about 1,000 prisoners would be affected — the most of any area in the country.

Holder told the commission that he supported the earlier release dates. Last year, Congress passed and President Barack Obama signed the Fair Sentencing Act, which reduces penalties for crack cocaine offenses in order to bring the sentences more in line with those for powder cocaine. But the act only addressed new cases, not old ones.

Holder said he supported applying the new, lower sentence guidelines to old cases. But Holder said prisoners who used weapons in committing their crimes or who have significant criminal histories should be prohibited from getting the benefit of reduced sentences.

In general, he said, officials acknowledge that the sentences of crack offenders were inappropriate when compared with powder cocaine offenders.

“As years of experience and study have shown, there is simply no just or logical reason why their punishments should be dramatically more severe than those of other cocaine offenders,” Holder said during his testimony.

The commission is expected to rule on the potential change within the next few months. Four members of the six-member commission would have to vote to support the idea. If that happens, Congress could still reject or modify the guidelines until the end of October.