Listen to Justin Bieber on iHeartRadio

(TMZ) - Justin Bieber's gonna face the full wrath of the law after his arrest for DUI and drag racing ... so says the top dog in Miami Beach, Mayor Philip Levine. 

[PHOTOS: Celebrity Mugshots]

Shortly after Justin's bust, Hizzoner was in Washington D.C. for a conference ... and told TMZ folks in his city won't stand for Bieber or anyone else recklessly speeding while drinking and driving. 

[Justin Bieber arrested for DUI, drag racing, & resisting arrest]

And if Bieber thinks he's gonna get special treatment while he's in custody -- the Mayor's got a strong opinion about that ... though he left a little wiggle room.  

[LISTEN: One Belieber is very upset about Justin Bieber]

He's a politician.

Check it out below!

Photo Credit Getty Images & Splash News