In a significant ruling today, a federal appeals court overturned a conviction of Salim Hamdan, Osama bin Laden’s driver, obtained through a military commission. Judge Brett Kavanaugh, a George W. Bush appointee seen as a possible conservative Supreme Court justice, wrote in a ruling for a three-judge panel of the DC Circuit Court that Hamdan could not be convicted under a military commission for “material support” for terrorist organizations before 2006, when the military commission process was inaugurated.