Cyrus Vance Jr., New York district attorney

Manhattan District Attorney Cyrus Vance Jr. will stop prosecuting low-level marijuana cases beginning in August, his office announced Tuesday, following a six-month review of public safety in jurisdictions where marijuana is no longer criminally prosecuted. The shift was one of a number announced by public officials Tuesday, signaling a substantial softening of marijuana enforcement across the city.

“The dual mission of the Manhattan D.A.’s Office is a safer New York and a more equal justice system,” Vance said in a statement. “The ongoing arrest and criminal prosecution of predominantly black and brown New Yorkers for smoking marijuana serves neither of these goals. Effective August 1, my office will decline to prosecute marijuana possession and smoking cases. We are in discussions with the mayor and police commissioner to consider limited exceptions to this policy, the goal of which is to radically reduce the criminal prosecution of these offenses.”

The Manhattan DA’s Office is set to join its counterparts across the East River in Brooklyn, where the DA’s Office has been declining to prosecute similar low-level possession cases since 2014.

According to Brooklyn District Attorney Eric Gonzalez, that policy has helped lead to a 75 percent decline in arrests citywide, “confirming that such policy does not adversely affect public safety.”

“I believe that low-level marijuana cases should be responded to with summonses rather than arrests,” Gonzalez said in a statement of his own on Tuesday.

Gonzalez said the office is also looking to expand a pilot program that declined to prosecute cases of public smoking of marijuana where a nuisance was not created. That pilot, launched three months ago, doubled the number of marijuana cases the office declined to prosecute, Gonzalez said.

The policy changes came as Mayor Bill de Blasio also pledged to change the way the police department approaches marijuana enforcement. In a speech before the Center for American Progress in Washington, D.C., on Tuesday, the mayor said the New York City Police Department will be overhauling its own marijuana arrest policy in the next 30 days.

“We must and we will end unnecessary arrests and end disparity in enforcement,” de Blasio said. “It’s time for those to be a thing of the past in New York City and all over this country.”