US President Joe Biden is issuing an executive order pardoning all Americans who have been federally convicted of “simple possession of marijuana”.
The move will only affect a relatively small number of marijuana convictions since most occur at the state level.
Mr Biden’s announcement stops short of a full decriminalisation of cannabis, which he promised as a presidential candidate.
Recent polls show that a majority of Americans believe weed should be legal.
“Sending people to prison for possessing marijuana has upended too many lives and incarcerated people for conduct that many states no longer prohibit,” Mr Biden said in a statement on Thursday.
“Criminal records for marijuana possession have also imposed needless barriers to employment, housing and educational opportunities,” he continued, adding that racial minorities were statistically far more likely to be jailed for cannabis.
Mr Biden, a Democrat, said he will call upon all state governors to issue their own marijuana pardons.
He is also directing the Department of Justice and the Department of Health and Human Services to review how cannabis is classified under federal law.
“We classify marijuana at the same level as heroin – and more serious than fentanyl,” said Mr Biden. “It makes no sense.”
Recreational marijuana is already legal in 19 states and Washington DC. Medical use is legal in 37 states and three US territories.
However, the drug remains illegal at the federal level, even in states where it can be legally bought and used by millions of adults.
The US jails a higher percentage of its population than any other nation, but relatively few people are in prison for simple possession of marijuana.
“More than 99% of federal drug offenders are sentenced for trafficking,” according to the US Bureau of Justice Statistics.
In a briefing on Thursday, a White House official told reporters there are “no individuals currently in federal prison solely for simple possession of marijuana”.
However, the pardon will remove “needless barriers to employment, housing, and educational opportunities” after convicts’ records are wiped clear, Mr Biden said.
US officials estimate there are “6,500 people with prior federal convictions for simple possession of marijuana” that Mr Biden will pardon.
His pardon will also affect thousands of Washington DC residents who have marijuana convictions, officials say.