Related Rule
United States of America
Practice Relating to Rule 3. Definition of Combatants
The US Air Force Pamphlet (1976) defines a combatant as “a direct participant in an armed conflict, traditionally a member of an armed force as specified in Article 4A(1) (2) and (3) [of the 1949 Geneva Convention III]”. 
United States, Air Force Pamphlet 110-31, International Law – The Conduct of Armed Conflict and Air Operations, US Department of the Air Force, 1976, § 1–2(b).
The US Naval Handbook (1995) states that the term “combatants”
embraces those persons who have the right under international law to participate directly in armed conflict during hostilities. Combatants, therefore, include all members of the regularly organized armed forces of a party to the conflict (except medical personnel, chaplains, civil defense personnel and members of the armed forces who have acquired civil defense status), as well as irregular forces who [fulfil the conditions for being considered armed forces]. 
United States, The Commander’s Handbook on the Law of Naval Operations, NWP 1-14M/MCWP 5-2.1/COMDTPUB P5800.7, issued by the Department of the Navy, Office of the Chief of Naval Operations and Headquarters, US Marine Corps, and Department of Transportation, US Coast Guard, October 1995 (formerly NWP 9 (Rev. A)/FMFM 1-10, October 1989), § 5.3.
The Report on US Practice (1997) states that the discussion on the status of combatant in the US military manuals is generally consistent with Article 43 of the 1977 Additional Protocol I. 
Report on US Practice, 1997, Chapter 1.1.
The US Manual for Military Commissions (2007) states:
“Lawful enemy combatant” means a person who is:
(A) a member of the regular forces of a State party engaged in hostilities against the United States;
(B) a member of a militia, volunteer corps, or organized resistance movement belonging to a State party engaged in such hostilities, which are under responsible command, wear a fixed distinctive sign recognizable at a distance, carry their arms openly, and abide by the law of war; or
(C) a member of a regular armed force who professes allegiance to a government engaged in such hostilities, but not recognized by the United States. 
United States, Manual for Military Commissions, published in implementation of the Military Commissions Act of 2006, 10 U.S.C. §§ 948a, et seq., 18 January 2007, Part II, Rule 103(14), pp. II-2 and II-3.
“Unlawful Enemy Combatant” means:
(A) a person who has engaged in hostilities or who has purposefully and materially supported hostilities against the United States or its co-belligerents who is not a lawful enemy combatant (including a person who is part of the Taliban, al Qaeda, or associated forces); or
(B) a person who, before, on, or after the date of the enactment of the Military Commissions Act of 2006, has been determined to be an unlawful enemy combatant by a Combatant Status Review Tribunal or another competent tribunal established under the authority of the President or the Secretary of Defense.
(C) “Co-belligerent” means any State or armed force joining and directly engaged with the United States in hostilities or directly supporting hostilities against a common enemy. 
United States, Manual for Military Commissions, published in implementation of the Military Commissions Act of 2006, 10 U.S.C. §§ 948a, et seq., 18 January 2007, Part II, Rule 103(24), p. II-4.
The US Manual for Military Commissions (2010) defines the term “Privileged Belligerent” as “an individual belonging to one of the eight categories enumerated in Article 4 of the Geneva Convention Relative to the Treatment of Prisoners of War [1949 Geneva Convention III]”. 
United States, Manual for Military Commissions, published in implementation of Chapter 47A of Title 10, United States Code, as amended by the Military Commissions Act of 2009, 10 U.S.C, §§ 948a, et seq., 27 April 2010, Rule 103 (26), p. II-4.
The US Naval Handbook (2007) states:
5.4.1 Combatants
Combatants are persons engaged in hostilities during an armed conflict. Combatants can be lawful or unlawful. The term “enemy combatant” refers to a person engaged in hostilities against the United States or its coalition partners during an armed conflict. The term “enemy combatant” also includes both “lawful enemy combatants” and “unlawful enemy combatants.”
5.4.1.1 Lawful Enemy Combatants
Lawful enemy combatants include members of the regular armed forces of a State party to the conflict; militia, volunteer corps, and organized resistance movements belonging to a State party to the conflict, which are under responsible command, wear a fixed distinctive sign recognizable at a distance, carry their arms openly, and abide by the laws of war; and members of regular armed forces who profess allegiance to a government or an authority not recognized by the detaining power. Lawful combatants are entitled to combatant immunity – that is, they cannot be prosecuted for their lawful military actions prior to capture.
Lawful combatants also include civilians who take part in a levee en masse. A levee en masse is a spontaneous uprising by the citizens of a nonoccupied territory who take up arms to resist an invading force without having time to form themselves into regular armed units. Combatant immunity for a levee en masse ends once the invading forces have occupied the territory.
5.4.1.2 Unlawful Enemy Combatants
Unlawful enemy combatants are persons not entitled to combatant immunity, who engage in acts against the United States or its coalition partners in violation of the laws and customs of war during armed conflict.
5.4.2 Noncombatants
Noncombatants are those members of the armed forces who do not take direct part in hostilities because of their status as medical personnel and chaplains. 
United States, The Commander’s Handbook on the Law of Naval Operations, NWP 1-14M/MCWP 5-12.1/COMDTPUB P5800.7, issued by the Department of the Navy, Office of the Chief of Naval Operations and Headquarters, US Marine Corps, and Department of Homeland Security, US Coast Guard, July 2007, §§ 5.4.1–5.4.2.
The Handbook also states:
Unlawful combatants who are members of forces or parties declared hostile by [a] competent authority are subject to attack at anytime during hostilities unless they are hors de combat … . 
United States, The Commander’s Handbook on the Law of Naval Operations, NWP 1-14M/MCWP 5-12.1/COMDTPUB P5800.7, issued by the Department of the Navy, Office of the Chief of Naval Operations and Headquarters, US Marine Corps, and Department of Homeland Security, US Coast Guard, July 2007, § 8.2.2.
The US Manual on Detainee Operations (2008) states: “Enemy combatants are personnel engaged in hostilities against the United States or its coalition partners during an armed conflict.” 
United States, Manual on Detainee Operations, Joint Chiefs of Staff, 30 May 2008, p. viii.
The manual also states:
Detainee Categories
Enemy Combatant. In general, a person engaged in hostilities against the United States or its coalition partners during an armed conflict. The term “enemy combatant” [EC] includes both “lawful enemy combatants” and “unlawful enemy combatants.”
(1) Lawful ECs, who are entitled to protections under the … [1949 Geneva Convention III], include members of the regular armed forces of a state party to the conflict; militia, volunteer corps, and organized resistance movements belonging to a state party to the conflict, which are under responsible command, wear a fixed distinctive sign recognizable at a distance, carry their arms openly, and abide by the laws of war; and, members of regular armed forces who profess allegiance to a government or an authority not recognized by the detaining power.
Lawful combatants are EPWs [enemy prisoners of war] upon capture, and are entitled to “combatant immunity” for their lawful pre-capture warlike acts. They may be prosecuted, however, for violations of the law of war. If so prosecuted, they still retain their status as EPWs.
(2) Unlawful ECs are persons not entitled to combatant immunity, who engage in or support acts against the United States or its coalition partners in violation of the laws and customs of war during an armed conflict. For purposes of the war on terrorism, the term unlawful EC is defined to include, but is not limited to, an individual who is or was part of or supporting Taliban or al Qaeda forces or associated forces that are engaged in hostilities against the United States or its coalition partners. 
United States, Manual on Detainee Operations, Joint Chiefs of Staff, 30 May 2008, pp. I-4–I-5; see also p. GL-3.
The US Military Commissions Act (2006), passed by Congress following the US Supreme Court’s decision in Hamdan v. Rumsfeld in 2006, amends Title 10 of the United States Code as follows:
§ 948a. Definitions
In this chapter: (1) UNLAWFUL ENEMY COMBATANT. – (A) The term “unlawful enemy combatant” means –
(i) a person who has engaged in hostilities or who has purposefully and materially supported hostilities against the United States or its co-belligerents who is not a lawful enemy combatant (including a person who is part of the Taliban, al Qaeda, or associated forces); or
(ii) a person who, before, on, or after the date of the enactment of the Military Commissions Act of 2006, has been determined to be an unlawful enemy combatant by a Combatant Status Review Tribunal or another competent tribunal established under the authority of the President or the Secretary of Defense.
(B) CO-BELLIGERENT. – In this paragraph, the term “co-belligerent”, with respect to the United States, means any State or armed force joining and directly engaged with the United States in hostilities or directly supporting hostilities against a common enemy.
(2) LAWFUL ENEMY COMBATANT. – The term “lawful enemy combatant” means a person who is –
(A) a member of the regular forces of a State party engaged in hostilities against the United States;
(B) a member of a militia, volunteer corps, or organized resistance movement belonging to a State party engaged in such hostilities, which are under responsible command, wear a fixed distinctive sign recognizable at a distance, carry their arms openly, and abide by the law of war; or
(C) a member of a regular armed force who professes allegiance to a government engaged in such hostilities, but not recognized by the United States.
(3) ALIEN. – The term “alien” means a person who is not a citizen of the United States. 
United States, Military Commissions Act, 2006, Public Law 109-366, Chapter 47A of Title 10 of the United States Code, 17 October 2006, p. 120 Stat. 2601, § 948a (1), (2) and (3).
The US Military Commissions Act (2009), which amends Chapter 47A of Title 10 of the United States Code, defines the term “privileged belligerent” as “an individual belonging to one of the eight categories enumerated in Article 4 of the Geneva Convention Relative to the Treatment of Prisoners of War [1949 Geneva Convention III]”. 
United States, Military Commissions Act, 2009, § 948a(6).
In the Hamdi case in 2004, involving a US citizen being detained indefinitely as an “enemy combatant”, the US Supreme Court reversed the dismissal of a habeas corpus petition by a lower court, recognized the power of the government to detain “enemy combatants”, but ruled that detainees who are US citizens must have the ability to challenge their detention before a neutral decision-maker. On the matter of the scope of the term “enemy combatant”, the Court stated:
The threshold question before us is whether the Executive has the authority to detain citizens who qualify as “enemy combatants.” There is some debate as to the proper scope of this term, and the Government has never provided any court with the full criteria that it uses in classifying individuals as such. It has made clear, however, that, for purposes of this case, the “enemy combatant” that it is seeking to detain is an individual who, it alleges, was “part of or supporting forces hostile to the United States or coalition partners” in Afghanistan and who “engaged in an armed conflict against the United States” there … We therefore answer only the narrow question before us: whether the detention of citizens falling within that definition is authorized. 
United States, Supreme Court, Hamdi case, Judgment, 28 June 2004.
In the In re Guantánamo Detainee cases in 2005, involving 11 coordinated habeas corpus civil actions brought against the US Government by various detainees being held at the US Naval Base at Guantanamo Bay, Cuba, the US Supreme Court found that “CSRT [Combatant Status Review Tribunal] procedures are unconstitutional for failing to comport with the requirements of due process.” Specifically regarding the CSRT’s reliance on a “Vague and Overly Broad Definition of ‘Enemy Combatant’”, the Court stated:
Although the government has been detaining individuals as “enemy combatants” since the issuance of the AUMF [Authorization for Use of Military Force, Pub. L. No. 107-40, § 2(a), 115 Stat. 224 (2001)] in 2001, it apparently did not formally define the term until the July 7, 2004 Order creating the CSRT. The lack of a formal definition seemed to have troubled at least the plurality of the Supreme Court in Hamdi, but for purposes of resolving the issues in that case, the plurality considered the government’s definition to be an individual who was “‘part of or supporting forces hostile to the United States or coalition partners’ in Afghanistan and who ‘engaged in an armed conflict against the United States’ there.” 542 U.S. 507, 159 L. Ed. 2d 578, 124 S. Ct. 2633, 2639 (quoting Brief for the Respondents) (emphasis added). …
The definition of “enemy combatant” contained in the Order creating the CSRT is significantly broader than the definition considered in Hamdi. According to the definition currently applied by the government, an “enemy combatant” “shall mean an individual who was part of or supporting Taliban or al Qaeda forces, or associated forces that are engaged in hostilities against the United States or its coalition partners. This includes any person who has committed a belligerent act or has directly supported hostilities in aid of enemy armed forces.” July 7, 2004 Order at 1 (emphasis added). Use of the word “includes” indicates that the government interprets the AUMF to permit the indefinite detention of individuals who never committed a belligerent act or who never directly supported hostilities against the U.S. or its allies. 
United States, District Court for the District of Columbia, In re Guantánamo Detainee cases, Judgment, 31 January 2005, pp. 59–60.
David Hicks, an Australian citizen, was captured in Afghanistan in December 2001 and afterwards detained at Guantánamo Bay Naval Base, Cuba. In March 2007, in the Hicks case, the accused became the first person to be tried and convicted under the US Military Commissions Act of 2006. Following a pre-trial agreement struck with the Convening Authority, the accused pleaded guilty to the charge of “providing material support for terrorism”. In April 2007, Hicks returned to Australia to serve the remaining nine months of a suspended seven-year sentence. In the case’s record of trial for the 30 March 2007 hearing, the military judge defined various terms contained in the charge to which the accused had pleaded guilty:
The term “unlawful enemy combatant” as it is used here means a person who has engaged in hostilities or who has purposefully and materially supported hostilities against the United States or its co-belligerents who is not a lawful enemy combatant including a person who is part of the Taliban, a1 Qaeda, or associated forces; or
A person who, before, on, or after the date of the enactment of the Military Commissions Act of 2006 has been determined to be an unlawful enemy combatant by a Combatant Status Review Tribunal or other competent tribunal established under the authority of the President of the United States or the Secretary of Defense. 
United States, Office of Military Commissions, Hicks case, Record of Trial, 26 and 30 March 2007.
In the Boumediene case in November 2008, which followed the US Supreme Court’s decision of 12 June 2008 that aliens held in Guantánamo and persons designated as enemy combatants on that territory were entitled to the writ of habeas corpus Boumediene v. Bush, 128 S. Ct. 229 (2008)], the US District Court for the District of Columbia granted a writ of habeas corpus to five of the six Guantánamo petitioners (including Lakhdar Boumediene) and denied the writ to a sixth petitioner (Belkacem Bensayah). The court memorandum order stated:
On August 27, 2008, the Court issued its Case Management Order (“CMO”), setting forth the procedural framework for the litigation of these six detainees’ habeas petitions.
Under the CMO, the Government bears the burden of proving “by a preponderance of the evidence, the lawfulness of the petitioner’s detention.” (CMO at 3.) The Government argues that petitioners are lawfully detained because they are “enemy combatants,” who can be held pursuant to the Authorization for the Use of Military Force [Pub. L. No. 107-40, §§ 1–2, 115 Stat. 224 (18 September 2001)] and the President’s powers as Commander in Chief.
The following definition of “enemy combatant”, governs the proceedings in this case:
An “enemy combatant”, is an individual who was part of or supporting Taliban or al Qaeda forces, or associated forces that are engaged in hostilities against the United States or its coalition partners. This includes any person who has committed a belligerent act or has directly supported hostilities in aid of enemy armed forces.
Boumediene v. Bush, 2008 WL 4722127, at *2 (Oct. 27, 2008 D.D.C.). [The CMO for this case] Accordingly, the question before this Court is whether the Government has shown by a preponderance of the evidence that each petitioner is being lawfully detained – i.e., that each is an “enemy combatant”, under the definition adopted by this Court. 
United States, District Court for the District of Columbia, Boumediene case, Memorandum Order, 20 November 2008, pp. 6–8.
[footnote in original omitted]
In the Hammamy case in April 2009, the US District Court for the District of Columbia denied a writ of habeas corpus to a petitioner detained at Guantánamo Bay, who had been captured in Pakistan by Pakistani authorities in April 2002 and transferred to US custody. Following court proceedings, conducted largely in camera due to the classified nature of much of the evidence, the memorandum order stated:
On November 28, 2008, the Court issued its Case Management Order (“CMO”) for the case. (Case Management Order, Nov. 28, 2008 …) That order was essentially a duplicate of the earlier CMO issued by the Court in the Boumediene v. Bush case, No. 04-cv-1 166, on August 27, 2008.
Under the CMO, the Government bears the burden of proving the lawfulness of the petitioner’s detention by a preponderance of the evidence. (CMO II.A.) The Government argues that petitioner Hammamy is lawfully detained because he is an “enemy combatant” who can be held pursuant to the Authorization for Use of Military Force [Pub. L. No. 107-40, §§ 1–2, 115 Stat. 224 (18 September 2001)] and the President’s powers as Commander-in-Chief. … The following definition of “enemy combatant,” previously adopted by this Court in the Boumediene cases, governs the proceedings in this case:
An “enemy combatant” is an individual who was part of or supporting Taliban or al Qaeda forces, or associated forces that are engaged in hostilities against the United States or its coalition partners. This includes any person who has committed a belligerent act or has directly supported hostilities in aid of enemy armed forces.
Boumediene v. Bush, 2008 WL 4722127, at *2 (D.D.C. Oct. 27, 2008). Accordingly, the question before this Court is whether the Government has shown by a preponderance of the evidence that petitioner Hammamy is being lawfully detained, i.e., that he is an “enemy combatant” under the definition adopted by this Court. 
United States, District Court for the District of Columbia, Hammamy case, Memorandum Order, 2 April 2009, pp. 3, 5 and 6.
[footnote in original omitted]
In the Hamlily case in 2009, in which the petitioners challenged the legality of their detention at Guantánamo by seeking writs of habeas corpus, the US District Court for the District of Columbia ruled that the US Government’s detention policy is generally consistent with the authority conferred on the US President under the Authorization for Use of Military Force (AUMF), Public Law 107-40, 115 Stat. 224, 18 September 2001, and core law of war principles that govern non-international armed conflicts. The Court stated in relation to the background of the case:
On March 13, 2009, in response to a prior order of this Court, the government [Department of Justice] submitted a refinement of its position with respect to its authority to detain those individuals being held at Guantánamo. The government proposed the following “definitional framework”:
The President has the authority to detain persons that the President determines planned, authorized, committed, or aided the terrorist attacks that occurred on September 11, 2001, and persons who harbored those responsible for those attacks. The President also has the authority to detain persons who were part of, or substantially supported, Taliban or al Qaida forces 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 hostilities, in aid of such enemy armed forces.
Resp’ts’ Mem. at 2. [Resp’ts’ Mem. Regarding the Detention Authority Relative to Individuals Held at Guantánamo Bay, In re: Guantánamo Bay Litigation, Misc. No. 08-442 (TFH), 13 March 2009].
To aid its consideration of these and other related issues, the Court held a hearing on April 17, 2009. Less than a week later, Judge Walton issued his opinion in Gherebi v. Obama, Civ. A. No. 04-1164, 2009 WL 1068955 (D.D.C. Apr. 22, 2009). Gherebi concerns the same question at issue here and Judge Walton’s thorough and thoughtful opinion advances this Court’s analysis considerably. He concluded that “the President has the authority to detain persons who were part of, or substantially supported, the Taliban or al-Qaeda forces that are engaged in hostilities against the United States or its coalition partners, provided that the terms ‘substantially supported’ and ‘part of’ are interpreted to encompass only individuals who were members of the enemy organization’s armed forces, as that term is intended under the laws of war, at the time of their capture.” Id. at *24. 
United States, District Court for the District of Columbia, Hamlily case, Judgment, 19 May 2009, pp. 3 and 5.
[footnotes in original omitted]
In its analysis of the government’s “definitional framework” providing for the detention of “Taliban or al Qaida forces or associated forces”, the Court stated with regard to “combatant” status in armed conflict:
Petitioners argue, just as they did in Gherebi, that because they cannot be classified as “combatants” under Article 4(A) of the Third Geneva Convention [1949 Geneva Convention III] or Article 43 of [1977] Additional Protocol I, they must be “civilians” – a classification that means they are not subject to military force (i.e., detention) “unless and for such time as they take a direct part in hostilities.” [Additional Protocol I] arts. 51(1), 51(3) … Putting aside for the moment the restrictive definition of “direct participation” advanced by petitioners, their advocacy of a detention authority based upon the dichotomy between combatants and civilians in traditional international armed conflicts is flawed. To begin with, the U.S. conflict with al Qaeda is a non-international armed conflict; hence, Article 4 and Additional Protocol I do not apply. Moreover, the government no longer seeks to detain petitioners on the basis that they are “enemy combatants.” Indeed, the government’s abandonment of this term is an implicit acknowledgment that “[i]n non-international armed conflict combatant status does not exist. … The treaty authorities that regulate non-international armed conflicts – Common Article 3, Additional Protocol II and the International Committee of the Red Cross’s Commentaries on both – in fact do not “make any reference whatsoever to the term ‘combatant.’” Gherebi, 2009 WL 1068955, at *18. Gherebi correctly observes that “petitioners evidently interpret this lack of protection for ‘combatants’ in non-international armed conflicts to mean that every individual associated with the enemy to any degree in such a conflict must be treated as a civilian.” Id.
This Court agrees that the lack of combatant status in non-international armed conflicts does not, by default, result in civilian status for all, even those who are members of enemy “organizations” like al Qaeda. Moreover, the government’s claimed authority to detain those who were “part of” those organizations is entirely consistent with the law of war principles that govern non-international armed conflicts. Common Article 3, by its very terms, contemplates the “detention” of “[p]ersons taking no active part in the hostilities, including members of armed forces who have laid down their weapons and those placed hors de combat,” and commands that they be treated “humanely.” Third Geneva Convention, art. 3(1). At a minimum, this restriction establishes that States engaged in non-international armed conflict can detain those who are “part of” enemy armed groups. Gherebi, 2009 WL 1068955, at *19. Similarly, Part IV of Additional Protocol II, in particular Article 13. … Such protections for “civilians” would be superfluous “if every member of the enemy in a non-international armed conflict is a civilian.” Gherebi, 2009 WL 1068955, at *20. The clear implication of Part IV, then, is that Additional Protocol II recognizes a class of individuals who are separate and apart from the “civilian population” – i.e., members of enemy armed groups. Indeed, it makes clear that “[t]hose who belong to armed forces or armed groups may be attacked at any time.” Int’l Comm. of the Red Cross, Commentary on the Additional Protocols of 8 June 1977 to the Geneva Conventions of 12 August 1949, at 1453 (Sandoz et al. eds. 1987) (discussing Article 13 of Additional Protocol II). As for the practical application of these principles, historical examples are few and far between. There are, however, several decisions of the International Criminal Tribunal for the former Yugoslavia (“ICTY”) that have recognized that, in a non-international armed conflict, membership in an armed group makes one liable to attack and incapacitation independent of direct participation in hostilities. 
United States, District Court for the District of Columbia, Hamlily case, Judgment, 19 May 2009, pp. 12–15.
[footnotes in original omitted]
In the Al-Bihani case in January 2010, involving an appeal by a Yemeni citizen held in detention at Guantánamo Bay since 2002 for the denial of a writ of habeas corpus by a district court, the US Court of Appeals for the District of Columbia, affirmed the order of the lower court, stating with regard to the detention of “unlawful enemy combatants”:
The AUMF [Authorization for Use of Military Force, Pub. L. No. 107-40, § 2(a), 115 Stat. 224, 224 (2001)] authorizes the President to “use all necessary and appropriate force against those nations, organizations, or persons he determines planned, authorized, committed, or aided the terrorist attacks that occurred on September 11, 2001, or harbored such organizations or persons.” AUMF § 2(a). The Supreme Court in Hamdi [Hamdi v. Rumsfeld, 542 U.S. 507] ruled that “necessary and appropriate force” includes the power to detain combatants subject to such force. 542 U.S. at 519. Congress, in the 2006 MCA, provided guidance on the class of persons subject to detention under the AUMF by defining “unlawful enemy combatants” who can be tried by military commission. 2006 MCA sec. 3, § 948a(1). The 2006 MCA authorized the trial of an individual who “engaged in hostilities or who has purposefully and materially supported hostilities against the United States or its co-belligerents who is not a lawful enemy combatant (including a person who is part of the Taliban, al Qaeda, or associated forces).” Id § 948a(1)(A)(i). In 2009, Congress enacted a new version of the MCA with a new definition that authorized the trial of “unprivileged enemy belligerents,” a class of persons that includes those who “purposefully and materially supported hostilities against the United States or its coalition partners.” Military Commissions Act of 2009 (2009 MCA) sec. 1802, §§ 948a(7), 948b(a), 948c, Pub. L. No. 111-84, tit. XVIII, 123 Stat. 2190, 2575- 76. The provisions of the 2006 and 2009 MCAs are illuminating in this case because the government’s detention authority logically covers a category of persons no narrower than is covered by its military commission authority. Detention authority in fact sweeps wider, also extending at least to traditional P.O.W.s, see id § 948a(6), and arguably to other categories of persons. But for this case, it is enough to recognize that any person subject to a military commission trial is also subject to detention, and that category of persons includes those who are part of forces associated with Al Qaeda or the Taliban or those who purposefully and materially support such forces in hostilities against U.S. Coalition partners. 
United States, Court of Appeals for the District of Columbia Circuit, Al-Bihani case, Judgment, 5 January 2010, pp. 8–9.
In March 2003, the US Deputy Assistant Attorney General, Office of Legal Counsel, Department of Justice, wrote a memorandum to the General Counsel of the Department of Defense which provided a legal analysis governing the military interrogation of alien “unlawful combatants” held outside the United States. The memorandum stated in part:
Historically, nations have been free to treat unlawful combatants as they wish, and in the United States this power has been vested in the President through the Commander-in-Chief Clause. As one commentator has explained, unlawful belligerents are “more often than not treated as war or national criminals liable to be treated at will by the captor. There are almost no regulatory safeguards with respect to them and the captor owes no obligation towards them.” RC. Hingorani, Prisoners of War 18 (1982) (emphasis added). See Ingrid Detter, The Law of War 148 (2d ed. 2000) (“'Unlawful combatants … enjoy no protection under international law”); William Winthrop, Military Law and Precedents 784 (2d ed. 1920) (unlawful belligerents are “[n]ot … within the protection of the laws of war”); A. Berriedale Keith, 2 Wheatons Elements of International Law 716 (6th ed. 1929) (“irregular bands of marauders are … not entitled to the protection of the mitigated usages of war as practised by civilized nations”); Oppenheim, 2 International Law, § 254, at 454 (6th ed. 1944) (“'Private individuals who take up arms and commit hostilities against the enemy do not enjoy the privileges of armed forces, and the enemy has, according to a customary rule of International Law, the right to treat such individuals as war criminals”.). The United States Supreme Court has recognized the important distinction between lawful and unlawful combatants. As the Supreme Court unanimously stated 60 years ago, “[b]y universal agreement and practice the law of war draws a distinction between the armed forces and the peaceful populations of belligerent nations and also between those who are lawful and unlawful combatants.” Ex parte Quirin, 317 U.S. 1, 30–31 (1942) (emphasis added). 
United States, Department of Justice, Office of Legal Counsel, John C. Yoo, Deputy Assistant Attorney General, Memorandum for William J. Haynes II, General Counsel of the Department of Defense, Military Interrogation of Alien Unlawful Enemy Combatants Held Outside the United States, 14 March 2003.