A Manhattan district attorney will stop prosecuting marijuana possession and smoking cases Wednesday, officials say.

In a letter, Manhattan District Attorney Cyrus R. Vance Jr., announced the D.A. Office's new policy to decline to prosecute marijuana possession and smoking cases will go into effect on August 1.

The policy is expected to reduce Manhattan marijuana prosecutions from approximately 5,000 per year to fewer than 200 per year, a 96 percent reduction.

The "Decline-To-Prosecute" policy follows national review of public safety in jurisdictions where marijuana is no longer criminally prosecuted, Vance says.

"Our research has found virtually no public safety rationale for the ongoing arrest and prosecution of marijuana smoking, and no moral justification for the intolerable racial disparities that underlie enforcement," Vance wrote.