3.      The Posse Comitatus Act has no application to the detention of an enemy combatant.

Petitioners claim (Amend. Pet. 38-40) that Padilla's detention violates the Posse Comitatus Act, 18 U.S.C. 1385, which criminally prohibits the willful use by any individual of "any part of the Army or the Air Force as a posse comitatus or otherwise to execute the laws," "except in cases and under circumstances expressly authorized by the Constitution or Act of Congress."  Id.  The petition also invokes a related statute authorizing the Secretary of Defense to promulgate regulations barring military personnel from direct participation in civilian law enforcement, 10 U.S.C. 375, as well an associated directive, DoD Directive 5525.5 (1986).  Petitioners' reliance on the posse comitatus provisions is in error.

As an initial matter, the Posse Comitatus Act effects a criminal prohibition against the military's engaging in the process of civil law enforcement.  There is no suggestion that violation of the Act or the related provisions affords grounds for release from detention in a habeas proceeding, independent of the substantive basis for the detention.  Cf. Robinson v. Overseas Military Sales Corp., 21 F.3d 502, 511 (2d Cir. 1994) (holding that there is no private right of action to enforce the Posse Comitatus Act).

Padilla's detention by the military as an enemy combatant, in any event, does not violate the posse comitatus provisions. Those provisions are directed by their terms to civilian law enforcement.  See United States v. Chon, 210 F.3d 990, 993 (9th Cir.) ("The PCA prohibits Army and Air Force military personnel from participating in civilian law enforcement activities."), cert. denied, 531 U.S. 910 (2000); United States v. Mullin, 178 F.3d 334, 342 (5th Cir.) ("The [Posse Comitatus] Act is designed to restrict military involvement in civilian law enforcement."), cert. denied, 528 U.S. 990 (1999).  Padilla's detention as an enemy combatant does not involve the military in civilian law enforcement, but instead involves a quintessentially military activity -- military detention of an enemy combatant in a time of armed conflict to ensure the national security.  That detention thus implicates the laws and customs of war, not the enforcement of civilian law.  Petitioners' contrary argument would disable the military from apprehending and detaining spies and saboteurs no matter how egregious their hostile acts.

The situation here likewise falls within the statutory exception for "cases and * * * circumstances expressly authorized by the Constitution or Act of Congress."  18 U.S.C. 1385; see DoD Directive 5525.5, para. E4.1.2.1 (Encl. 4) (excepting "[a]ctions that are taken for the primary purpose of furthering a military or foreign affairs function of the United States").  Padilla's detention was directed by the President in the exercise of his powers under Article II of the Constitution as Commander in Chief, and the detention also is authorized by two Acts of Congress.  First, the detention of enemy combatants is encompassed within Congress's express authorization to the President "to use force against those 'nations, organizations, or persons he determines' were responsible for the September 11 terrorist attacks."  Hamdi, 296 F.3d at 283 (quoting 115 Stat. 224) (emphasis added by court of appeals).  Second, Congress has appropriated funding to the Department of Defense to pay for expenses incurred in connection with "the maintenance, pay, and allowances of prisoners of war, [and] other persons in the custody of the Army, Navy, or Air Force whose status is determined by the Secretary concerned to be similar to prisoners of war."  10 U.S.C. 956(5); see 10 U.S.C. 956(4) (appropriating funding for the "issue of authorized articles to prisoners and other persons in military custody").  By funding the detention of "prisoners of war" and persons "similar to prisoners of war," Congress has authorized the military detention of enemy combatants.  Therefore, neither the Posse Comitatus Act nor its related provisions in any way bar the military detention of Padilla as an enemy combatant.