Police will loosen enforcement of some marijuana crimes beginning in September, the mayor and police commissioner announced Tuesday.

People caught smoking pot in public will receive a summons rather than being arrested. That's assuming the suspect is not actively on probation, parole or the subject of an existing arrest warrant. Suspects who are not carrying identification, who have a recent history of violence or are caught smoking while driving could also face arrest.

"We believe this will result in thousands of fewer arrests," says Mayor Bill de Blasio. "In fact, next year we think at least 10,000 fewer New Yorkers will be arrested under this new policy."

The figure comes from NYPD projections based on 2017 arrest records and patterns. 

The new policy will begin on Sept. 1. It follows the recommendation of the mayor's 30-day working group on marijuana enforcement.

Noami Braine, a Brooklyn College sociology professor, says evidence from areas that have legalized marijuana have shown little evidence of increased drug usage.

"Some people are concerned that any loosening of marijuana laws will lead to rampant drug use among adolescence," Braine says. "In places where marijuana has been legalized, there is absolutely no indication of significant changes in drug use among adolescents and young adults."