The U.S. Sentencing Commission voted unanimously Friday to allow 46,290 federal prisoners sentenced under harsh guidelines for drug offenses to seek a reduction in their sentences. The vote made retroactive an earlier change in the guidelines.

Inmates will have to go before a judge and ask that their sentences be reduced. If the judge grants the maximum reduction, about two years will be shaved off the average inmate’s sentence. Prisoners shouldn’t start packing their bags yet though; they won’t be able to begin petitioning judges for the reductions until November 2015.

The commission’s vote was a good start toward reforming drug sentences, but more must be done, according to the chair of the commission. “The step the commission is taking today is an important one, but only Congress can bring about the more comprehensive reforms needed to reduce disparities, fully address prison costs and populations, and make the federal criminal justice system work better,” District Judge Patti Saris, chair of the Sentencing Commission, said in a prepared statement.

Much of the unfairness in drug sentencing is because of the focus on the quantity of drugs involved in the deal, rather than the role an individual defendant played in the transaction. Thus, low-level couriers get sentences similar to those of drug-ring leaders.

Some prosecutors disagree with the move. They’re concerned that courtrooms, particularly in areas with high incidences of drug trafficking such as South Texas, will be inundated with petitioners hoping for sentence reductions. “We’re just disappointed,” Dennis Boyd, executive director of the National Association of Assistant U.S. Attorneys, told The Washington Post on Friday. “We were hoping for something different.”

Prosecutors are also concerned that the ruling might allow those with violent criminal histories to be released. For that reason, the sentencing commission suggested allowing a year before petitioners can seek release, thus giving investigators time to remove those with a history of violence from lists of who can seek reductions.

Attorney General Eric Holder called the move “a milestone” and said the Bureau of Prisons would immediately begin notifying inmates who are eligible to apply for a sentence reduction.

The American Civil Liberties Union applauded the vote. “Making these new guidelines retroactive will offer relief to thousands of people who received overly harsh sentences under the old sentencing guidelines,” said ACLU senior counsel Jesselyn McCurdy, who earlier testified in favor of the reductions. “The Sentencing Commission absolutely did the right thing today by putting the power to decide retroactivity in judges’ hands.”

-Steve Straehley

To Learn More:

U.S. Sentencing Commission News Release (pdf)

Thousands of Felons Could Have Drug Sentences Lessened (by Jerry Markon and Rachel Weiner, Washington Post)

Retroactive Sentencing Reductions Will Bring Relief to Thousands (by Adam Klasfeld, Courthouse News Service)

Federal Agency Approves Early Release Of Some 46,000 Drug Prisoners (by Nicole Flatow, Think Progress)

Justice Dept. Searching for Crack Prisoners to Release (by Steve Straehley, AllGov)

Prison Sentences for Black Men Are 20% Longer Than Those for White Men for Same Crimes (by Noel Brinkerhoff, AllGov)