(1) A person who planned, authorized, committed, or aided the terrorist attacks that occurred on September 11, 2001, or harbored those responsible for those attacks.
(2) A person who was a part of or substantially supported al-Qaeda, the Taliban, or associated forces that are engaged in hostilities against the United States or its coalition partners, including any person who has committed a belligerent act or has directly supported such hostilities in aid of such enemy forces.
Now the thing is, this administration has been showering substantial support (in the form of weapons and money) upon the "rebels" in Syria and Libya, many of whom, lo and behold, are members of, or closely aligned with al-Qaeda, the Taliban, or associated forces!
So Obama can indefinitely detain himself - and anyone else in his administration who has taken part in this fiasco! Somehow I don't think we'll be seeing the black helicopters swarm the White House anytime soon though.