As an initial matter, “there are a lot of people who are not covered by the AUMF,” explained Benjamin Wittes, editor-in-chief of the national security blog, Lawfare, and a senior fellow at the Brookings Institution, told CNN.

“When you look at a self-radicalized person in Florida who declares his allegiance to ISIS, can you say he is under detention authority? Not even close,” Wittes added.

Professor Matthew Waxman of Columbia Law School, who served in the Department of Defense overseeing detainee policies under the Bush administration, explained that “the government to date has been relying on perhaps a plausible, but very stretched, interpretation of the AUMF to include ISIS (for purposes of drone strikes),” and the concept of further relying on the AUMF to detain ISIS-supporters not captured on the battlefield, but arrested in the US, would be a “big stretch.”

“We’ve come a point where federal courts may say AUMF has lapsed. …The practical circumstances on the ground are too different at this point from the aftermath of September 11th for the AUMF to continue to provide legal authority to detain anyone at Guantanamo. …It’s not 2004 anymore,” said Wells Dixon, a senior staff attorney at the Center for Constitutional Rights, who has also represented several detainees at Guantanamo.