Thousands of marijuana convictions set to be tossed out by California district attorney San Francisco's district attorney will review thousands of cases immediately.

 -- Thousands of people currently sitting in jail on marijuana convictions are set to get a reprieve thanks to San Francisco District Attorney George Gascón.

The district attorney's office on Wednesday announced it will be retroactively applying Proposition 64, which legalized marijuana in California, and "reviewing, recalling and resentencing up to 4,940 felony marijuana convictions and dismissing and sealing 3,038 misdemeanors which were sentenced prior to the initiative’s passage." The office will look at convictions back to 1975, it said.

Proposition 64 was passed in November 2016 and immediately legalized using and growing marijuana for personal use. Sale and taxation of marijuana by the state went into effect on Jan. 1, however. California residents 21 and older can legally possess up to 28.5 grams of marijuana (8 grams concentrated marijuana), though it remains illegal to use while driving or possess on school grounds, according to state law.

Gascón criticized federal drug policy in a statement announcing his office's plans to erase the marijuana convictions from some offenders' records.

"While drug policy on the federal level is going backwards, San Francisco is once again taking the lead to undo the damage that this country's disastrous, failed drug war has had on our nation and on communities of color in particular," Gascón said in a statement. "Long ago we lost our ability to distinguish the dangerous from the nuisance, and it has broken our pocket books, the fabric of our communities, and we are no safer for it."

The district attorney's office noted that with the passage of Proposition 64 individuals who were convicted could petition for dismissal or a lesser sentence, but few people took advantage of the offer.

Now that work will be done for them without the need for a costly lawyer.

"This isn’t just an urgent issue of social justice here in California –- it's a model for the rest of the nation," Lt. Gov. Gavin Newsom said in a statement.

San Francisco ABC station KGO spoke to Bishop Ron Allen, with the International Faith Based Coalition, who said he opposes the move and favors rehabilitation.

"We want to see them in jail, educated, absolutely turned around," Allen told KGO. "Please do not release them back into the community."

Gascón said in Wednesday's press conference he wasn't sure how long the process would take or how much it would cost, but that misdemeanor convictions could be reviewed fairly quickly.