Whether Congress authorized the military detention of a United States citizen alleged to have fought for the Taliban in Afghanistan.
Holding
Yes. The AUMF authorized detention of a citizen who was part of or supported forces hostile to the United States or its coalition partners and who engaged in armed conflict against the United States in Afghanistan.
Reasoning
The plurality did not decide whether the President possessed independent Article II authority to detain citizen enemy combatants. Instead, it held that Congress supplied authorization through the AUMF, which permitted the President to use “all necessary and appropriate force” against those connected to the September 11 attacks and those who harbored them.
Capture and detention of enemy combatants are longstanding, fundamental incidents of war. Detention serves a nonpunitive purpose: preventing a captured fighter from returning to the battlefield. Because the Taliban harbored and supported al Qaeda, detaining a person who actually fought with Taliban forces against the United States fell within the force Congress authorized.
The plurality also concluded that the AUMF satisfied the Non-Detention Act’s requirement that a citizen be detained only “pursuant to an Act of Congress,” assuming that statute applies to military detention. The AUMF need not expressly use the word “detention” when detention is a necessary and accepted incident of the authorized use of military force.
Citizenship did not itself bar military detention. Relying on Ex parte Quirin and the law-of-war understanding that a citizen can join enemy forces, the plurality reasoned that a citizen who takes up arms against the United States poses the same battlefield threat as an alien combatant. Its holding, however, was confined to the Government’s stated definition and allegations in this case.