District Attorney George Gascón said the city will retroactively apply California’s marijuana-legalization laws to past criminal cases, reported the San Francisco Chronicle.

The upshot: the city will dismiss more than 3,000 misdemeanor marijuana convictions in the city dating as far back as 1975 and review nearly 5,000 felony cases for possible action.

Medical marijuana has been legal in California for two decades, accounting for roughly $2 billion in annual sales.

California voted to legalize adult-use cannabis sales in 2016 by passing Proposition 64. The recreational use of marijuana in California is now allowed for those 21 and older and are permitted the possession of up to one ounce of cannabis. However, actual legal recreational weed sales were on hold until January 2018 while state lawmakers decided on the regulatory framework for the new legal market.

The new law also allows anyone with a marijuana conviction that wouldn’t have resulted in a crime (or a lesser one) under Prop. 64 to petition the court to dismiss the case. The district attorney decided to have prosecutors handle this all at once.

Despite California’s legalization, marijuana sales remain illegal under federal law.