It’s also important that the key 2011 provision in which Congress said whom the president can detain “exempts U.S. citizens entirely,” as Benjamin Wittes explained at the time. Similarly the 2009 Military Commission Act—which Graham wrote—states that American citizens may not be tried by military commission.

Tsarnaev an enemy combatant? John McCain and Lindsey Graham’s harmful campaign to undermine American justice. - Slate Magazine