Justin Bieber Will NOT Be Charged in Alleged Photog Battery

11/21/2012 12:40 AM PST

Justin Bieber has a lot to be thankful for ... not only is he back in Selena's good graces -- he won't be charged for allegedly beating up a paparazzo ... TMZ has learned.

We broke the story ... Justin was a suspect in a misdemeanor battery, after a photog claimed he and the singer got into a physical altercation back in May on the mean streets of Calabasas.  The photog called 911 and filed a police report.

We've learned the L.A. County D.A. will NOT file criminal charges, because of conflicting witness accounts and an overall lack of evidence.

Fun Facts about Calabasas:

-- The Menendez brothers went to Calabasas High School
-- Elizabeth Berkley also went there ...but was nicer to her parents