The L.A. County District Attorney's office tells TMZ the case was dropped because Tiny completed 24 sessions of a certified drug diversion program in Georgia.
T.I. and Tameka were pulled over and arrested on Sunset Boulevard back in September. They were booked for possession of a controlled substance.
The D.A. dropped the case against T.I. since he was already headed back to prison ... the arrest alone was enough to violate his federal probation.