As of Wednesday, the Manhattan District Attorney's office will stop prosecuting most cases for smoking and possessing marijuana.

The change was promised in May by DA Cy Vance Jr., and is expected to reduce the number of marijuana prosecutions by around 96 percent, according to a release from his office. Last year, Vance's office oversaw 5,500 marijuana cases; after the policy is implemented, that number is supposed to drop to under 200.

Per the release, New Yorkers will continue to be prosecuted for marijuana offenses in Manhattan if they are believed to be selling it (possessing 10 individual bags or more) or in cases "where there is additional information from the NYPD or from our Office which demonstrates that the individual otherwise poses a significant threat to public safety."

Asked to explain further what that second exception meant, Vance told WNYC's Richard Hake this morning that the NYPD "will have to demonstrate why they believe this individual poses a threat of violence or public safety and at that point the decision to prosecute will have to be reviewed by a supervisor in our complaint room."

"There are areas where danger is also a nuisance—smoking next to young children who are getting out of school," Vance added.

Brooklyn District Attorney Eric Gonzalez had previously announced a policy to decline to prosecute low-level marijuana offenses, which overwhelmingly affect Black and brown New Yorkers, and last week he issued a release claiming that the number of marijuana charges dropped by more than 90 percent between January and June of this year.

The DAs in the Bronx, Staten Island, and Queens have so far not committed to the same policies.

"I think it means that if you are going to smoke or possess marijuana that you need to do so thoughtfully and intelligently," Vance said, when asked about the discrepancies citywide.

Eliza Orlins, a staff attorney for the Legal Aid Society in Manhattan, said that while the new policy is a "great big step forward," the public safety exception seemed to give a lot of latitude to the NYPD.

"As far as we know the NYPD is going to continue to make these arrests, to issue these summonses," Orlins said.

On WNYC, Vance did say that while he is calling for the New York legislature to legalize marijuana, he felt that right now, the appropriate punishment for possession and public smoking is a summons.

Those summonses, if unanswered, effectively turn into warrants, Orlins says. It is not uncommon for someone to be arrested for an unrelated charge where they would normally receive a Desk Appearance Ticket and be sent on their way. Instead, an old marijuana summons is found and so they spend the night in jail.

"We've seen Vance make these sweeping announcements in the past, but what ends up happening is that the exceptions swallow the rule," Orlins noted, pointing to an announcement Vance made this year about not asking for bail in certain misdemeanor cases. "In practice, we saw no change," she said.

Danny Frost, a spokesman for Vance's office, explained the public safety exception was a way of "giving ourselves space for the rare event when arraigning on the marijuana charge gives us leverage to investigate a separate serious offense that requires additional investigation." Frost added, "This is likely to be only a handful of cases per year."

Frost said that being included on the NYPD's gang database that reportedly includes the names of more than 40,000 New Yorkers, would not meet the DA's threshold for the public safety exception.

A spokesman for the NYPD referred us to their new policy, beginning on September 1, of issuing only summonses and not making arrests for marijuana offenses, except "if they are on parole or probation, have an open warrant, a violent criminal history or fail to show identification."

Last year, Vance, who won a third term last year after running unopposed, was criticized for dropping a fraud investigation against Ivanka Trump and Donald Trump Jr., not pressing charges against Harvey Weinstein in 2015, and for taking campaign donations from an attorney connected to Weinstein. Vance later returned some of the contributions, and earlier this year adopted a stricter set of guidelines for taking donations.