Justin Bieber was arrested for DUI ... TMZ has learned.
Law enforcement tells us ... Bieber was busted in Miami Beach and it didn't end with DUI ... he was also busted for drag racing.
The arrest occurred early Thursday morning.
Bieber is now in custody and is at the police department where he is being tested -- presumably to more precisely measure his blood alcohol level. Our law enforcement sources say Justin was given a field sobriety test at the scene ... and failed.
His next stop will be jail, where he will be booked and processed and bail will be set.
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