Attorney General Eric Holder endorsed a proposal that would result in shorter prison sentences for many nonviolent drug traffickers, saying the change would rein in runaway federal prison costs and create a fairer criminal justice system.

Holder’s backing on Thursday for a U.S. Sentencing Commission proposal to lower the guideline penalties is part of a broader Justice Department effort to lessen punishment for nonviolent drug dealers. He has been pressing to ease long mandatory sentences and has called for greater discretion for judges in sentencing.