NASCAR has asked a federal judge to reverse his ruling and keep driver Jeremy Mayfield off the track.

NASCAR filed the motion asking U.S. District Court Judge Graham Mullen to reinstate Mayfield's ban. He was suspended May 9 after failing a random drug test, and NASCAR said he tested positive for methamphetamine.

The latest twist comes after Mullen's decision last week to grant an injunction clearing him to compete. Mullen said the chance of a false positive on his drug test was "quite substantial."

NASCAR disputes Mullen's conclusion, and says Mayfield poses a threat to public safety. NASCAR also filed a notice saying it plans to bring the case before a federal appeals court.