Justin Bieber's Staying Silent on Headbutt Case, Rolling Dice with D.A.

Justin Bieber ain't singing to the cops about his alleged headbutting of a guy at a pre-Grammy party, and now the case is about to land on the District Attorney's desk.

Sources close to Justin tell TMZ he hasn't said a word to cops about the misdemeanor battery case where he's accused of going off on a guy for shooting video of him "play fighting" with Kyle Massey. We're told the Biebs plans to stay radio silent and take his chances with the D.A.'s office.

The move could work in Justin's favor -- the only evidence appears to be video which doesn't clearly show the attack. Plus, as we've reported ... the alleged victim doesn't want to press charges.

Law enforcement sources tell us the case looks thin, but the D.A. will make the final call.