Amanda Bynes isn't mentally competent to stand trial in her DUI case, according to legal docs filed Tuesday morning at the LAX Airport courthouse by her criminal defense attorney, Breaking Celebrity News is exclusively reporting.

The troubled starlet has been under a temporary conservatorship obtained by her mother Lynn, after starting a fire in a driveway near her parents' house.

Under California Penal Code 1368, if "counsel informs the court that he or she believes the defendant is, or may be, mentally incompetent, the court shall order that the question of the defendant mental competence is to be determined in a hearing."