‘Simple Life” star Nicole Richie has been arrested on DUI charges that might actually stem from substance abuse.

Early Monday, following 911 calls from two drivers, highway patrol officers found Nicole driving her SUV the wrong way, alone in the carpool lane of a Burbank freeway. (The kicker: When pulled over, she was on her cell phone.) After failing a sobriety test, she was arrested at 1:45 a.m., taken into custody, booked with a misdemeanor DUI charge at 4:50 a.m. and released on $15,000 bail around 7:15 a.m.