US Attorney General Eric Holder says America's prison policy is failing and has announced a reduction in the use of mandatory sentencing for some drug offences.
Mr Holder said certain low-level drug offenders with no ties to organised crime will no longer face mandatory minimum sentences.
''We need to ensure that incarceration is used to punish, deter and rehabilitate - not merely to convict, warehouse and forget," Mr Holder said in a speech to the American Bar Association in San Francisco on Monday.
He advocated sending people convicted of low-level offences to drug treatment and community service programmes instead of prison.
The BBC reports the United States has one of the world's biggest prison populations. Some 47% of prison inmates have been incarcerated for drug offences, according to the Federal Bureau of Prisons.