Samantha Ronson was arrested for a DUI Mon. morning at 10:30 a.m. in Calif. after a night of drinking and DJ'ing in Las Vegas.

Ronson, Lindsay Lohan's former girlfriend, was reportedly pulled over by police near Baker, Calif. For speeding in her black Porsche Targa, clocked at 89 m.p.h. in a 70 zone.

An officer told US Weekly that "she was arrested on [two] misdemeanors of driving under the influence."

Roson, who had DJ'ed the previous night at Lavo nightclub in Las Vegas, was driving home alone to Los Angeles. She told the arresting officer "she had consumed alcohol early [that] morning or late last night...went to bed and got up this morning" to drive home to California.

The officer reported that after a failed field sobriety test, in which 33-year-old Ronson did not pass, showing "signs of being impaired" during balance tests. Ronson refused a non-mandatory roadside breathalyzer and was arrested at the scene.

The 102 lbs. Ronson allegedly exceeded the legal limit when she was tested during booking.

Samantha Ronson was released from the San Bernadino County Jail sometime between 5:30 and 6 p.m. according to reports.