WHITE PLAINS - Kerry Kennedy's drugged-driving trial began today in White Plains, with opening statements from both sides and the start of the prosecution's case.

Kennedy was arrested in July 2012 for allegedly driving erratically and sideswiping a tractor-trailer on I-684 while impaired by Ambien, a sleep aid. She was found slumped over her steering wheel on Route 22, near Armonk.

The man who found her and the first police officer on the scene described Kennedy as "disoriented" and apparently under the influence of a drug. Kennedy's attorneys claim she had taken Ambien by mistake that morning, which left her in a semi-asleep state.

Prosecutors argue that Kennedy should have known something was wrong and stopped driving, but Kennedy's attorney Gerald Lefcourt says he will show the drug impaired Kennedy's ability to recognize that.

Kennedy, the daughter of the late Robert F. Kennedy, was joined in court by her mother Ethel and her brothers Robert and Douglas, along with Douglas' wife.