Stephanie Pratt pleaded not guilty to misdemeanor DUI in court on Friday. Pratt, 23, was arrested in October after celebrating Holly Montag’s birthday at Empire in Hollywood. The star of MTV’s The Hills will enroll in a 30-day residential rehab facility.

This is not the socialite’s first scrap with the law. In 2006, Stephanie — who revealed her battle with bulima earlier this year — was arrested for shoplifting from a Neiman Marcus in Honolulu, where she was working as a production assistant on the set of Lost.

If convicted, Stephanie faces up to six months in jail and a $1,000 fine.