Related Rule
United States of America
Practice Relating to Rule 110. Treatment and Care of the Wounded, Sick and Shipwrecked
The US Field Manual (1956) provides that the “wounded and sick shall be cared for by the party to the conflict in whose power they may be” and that “they shall not wilfully be left without medical assistance and care, nor shall conditions exposing them to contagion or infection be created”. 
United States, Field Manual 27-10, The Law of Land Warfare, US Department of the Army, 18 July 1956, as modified by Change No. 1, 15 July 1976, § 215.
The manual reproduces Articles 15 and 18 of the 1949 Geneva Convention I. 
United States, Field Manual 27-10, The Law of Land Warfare, US Department of the Army, 18 July 1956, as modified by Change No. 1, 15 July 1976, §§ 216 and 219.
The US Air Force Pamphlet (1976) reproduces Article 12 of the 1949 Geneva Convention I. 
United States, Air Force Pamphlet 110-31, International Law – The Conduct of Armed Conflict and Air Operations, US Department of the Air Force, 1976, § 12-2(a).
The US Instructor’s Guide (1985) reproduces Article 12 of the 1949 Geneva Convention I. 
United States, Instructor’s Guide – The Law of War, Headquarters Department of the Army, Washington, April 1985, p. 8.
The US Naval Handbook (1995) provides that parties shall take all possible measures to ensure the care of the wounded, sick and shipwrecked. 
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), § 11.4.
The US Naval Handbook (2007) states:
Combatants who have been rendered incapable of combat (hors de combat) by wounds, sickness, shipwreck … are entitled to special protections including assistance and medical attention if necessary. Parties to the conflict must … take all possible measures to … protect them from harm and ensure their care. 
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, § 11.6.
The US Manual on Detainee Operations (2008) states:
Legal Considerations
a. As a subset of military operations, detainee operations must comply with the law of war during all armed conflicts, however such conflicts are characterized, and in all other military operations …
c. The four Geneva Conventions of 1949 are fully applicable as a matter of international law to all military operations that qualify as international armed conflicts … The principles reflected in these treaties are considered customary international law, binding on all nations during international armed conflict. Although often referred to collectively as the “Geneva Conventions,” the specific treaties are:
(1) [1949] Geneva Convention [I] … This convention provides protection for members of the armed forces and other persons on the battlefield who are no longer actively participating in hostilities as the result of becoming wounded or sick. It also regulates the conduct and treatment of medical and medical support personnel. It requires humane treatment for wounded and sick personnel who fall into enemy hands, with an express requirement that such individuals be … provided necessary and adequate care. 
United States, Manual on Detainee Operations, Joint Chiefs of Staff, 30 May 2008, pp. I-2–I-3.
The manual further states:
DODD 2310.01E [Department of Defense Directive, The Department of Defense Detainee Program] requires that all DOD [Department of Defense] personnel and contractors will apply, without regard to a detainee’s legal status, at a minimum, the standards articulated in Common Article 3 to the Geneva Conventions of 1949 …
Article 3 Common to the Geneva Convention of 1949
In the case of armed conflict not of an international character occurring in the territory of one of the High Contracting Parties, each Party to the conflict shall be bound to apply, as a minimum, the following provisions:
(1) Persons taking no active part in the hostilities … shall in all circumstances be treated humanely …
To this end, the following acts are and shall remain prohibited at any time and in any place whatsoever with respect to the above-mentioned persons:
(2) The wounded and sick shall be … cared for. 
United States, Manual on Detainee Operations, Joint Chiefs of Staff, 30 May 2008, pp. III-11–III-12.
In July 2006, the US Deputy Secretary of Defense issued a memorandum to senior military and civilian personnel in the Department of Defense (DoD) on the subject of common Article 3 of the 1949 Geneva Conventions and its application to the treatment of detainees:
The Supreme Court Hamdan v. Rumsfeld, 548 US 557, 29 June 2006] has determined that Common Article 3 to the Geneva Conventions of 1949 applies as a matter of law to the conflict with Al Qaeda. The Court found that the military commissions as constituted by the Department of Defense are not consistent with Common Article 3.
It is my understanding that, aside from the military commission procedures, existing DoD orders, policies, directives, execute orders, and doctrine comply with the standards of Common Article 3 … In addition, you will recall the President’s prior directive [President George W. Bush, Memorandum, Humane Treatment of Al Qaeda and Taliban Detainees, 7 February 2002] that “the United States Armed Forces shall continue to treat detainees humanely,” humane treatment being the overarching requirement of Common Article 3.
You will ensure that all DoD personnel adhere to these standards. In this regard, I request that you promptly review all relevant directives, regulations, policies, practices and procedures under your purview to ensure that they comply with the standards of Common Article 3. 
United States, Department of Defense, Deputy Secretary of Defense, Gordon England, Memorandum, Application of Common Article 3 of the Geneva Conventions to the Treatment of Detainees in the Department of Defense, 7 July 2006.
According to the Report on US Practice, it is the opinio juris of the United States that the wounded and sick in internal armed conflicts should be respected and protected in accordance with Article 7 of the 1977 Additional Protocol II. They must receive the medical care required by their condition. 
Report on US Practice, 1997, Chapter 5.1.
The US Field Manual (1956) states: “Only urgent medical reasons will authorize priority in the order of treatment to be administered.” 
United States, Field Manual 27-10, The Law of Land Warfare, US Department of the Army, 18 July 1956, as modified by Change No. 1, 15 July 1976, § 215.
(emphasis added)
The US Air Force Pamphlet (1976) states: “Priority in order of treatment is justified only by urgent medical reasons.” 
United States, Air Force Pamphlet 110-31, International Law – The Conduct of Armed Conflict and Air Operations, US Department of the Air Force, 1976, § 12-2.
(emphasis added)
The US Naval Handbook (1995) states: “Priority in order of treatment may only be justified by urgent medical considerations.” 
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), § 11.4.
(emphasis added)
The US Naval Handbook (2007) states:
Wounded and sick personnel falling into enemy hands must be treated humanely and cared for without adverse distinction along with the enemy’s own casualties. Priority in order of treatment may only be justified by urgent medical considerations. 
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, § 11.6.
In 1987, the Deputy Legal Adviser of the US Department of State affirmed: “We support the principle that when [the wounded, sick and shipwrecked] are given medical treatment, no distinction among them be based on any grounds other than medical ones.” 
United States, Remarks of Michael J. Matheson, Deputy Legal Adviser, US Department of State, The Sixth Annual American Red Cross-Washington College of Law Conference on International Humanitarian Law: A Workshop on Customary International Law and the 1977 Protocols Additional to the 1949 Geneva Conventions, American University Journal of International Law and Policy, Vol. 2, 1987, p. 423.
According to the Report on US Practice, it is the opinio juris of the United States that there should be no distinction among the wounded and sick on any but medical grounds. 
Report on US Practice, 1997, Chapter 5.1.