Well...he has been acting like a bit of a massive prick lately, but he has been arrested for DUI, speeding, driving on an invalid license, resisting arrest, as you may have heard, and released on a bail bond of $2500. And apparently he's also been diagnosed with depression, and has been taking antidepressants (whether that's true or not I don't know...It still doesn't excuse acting like a massive prick). And if found guilty, he could spend six months in jail.
It seems to have caused a massive stir though amongst people. You have half the internet tweeting "free justin bieber" and camping outside his current hotel.