Rep. Kennedy says he was disoriented by prescription drugs, specifically the sleep medication Ambien and the anti-nausea medication Phenergran (which can cause drowsiness). Getting in front of the wheel after taking a sleeping pill, of course, is just as dangerous as driving drunk, and just as illegal. The special treatment that Kennedy got really is outrageous: Anyone else almost certainly would have had to spend the night in lockup.
There is a small possibility that Kennedy didn’t know what he was doing: Ambien causes somnambulism in a tiny percentage of users (fewer than one in a thousand, according to the prescribing information, though some litigious busybodies have started claiming that that estimate is too low.) (UPDATE: They’re mocking the Ambien story over at Wonkette: “Was his excuse written by the producers of Dateline NBC?”)
Another wrinkle: Patrick Kennedy has been quite open about being diagnosed bipolar. Could the prescription drugs he wasn’t taking possibly be as important as those he was?