A lawyer for Osama bin Laden’s former driver urged the Supreme Court on Tuesday to curb President George W. Bush’s use of wartime powers to prosecute terror suspects held at a U.S. military base at Guantanamo Bay, Cuba.

Attorney Neal Katyal, who represents Salim Ahmed Hamdan, told justices the military commissions established by the Pentagon on Bush’s orders are flawed because they violate basic military justice protections.