Related Rule
United Kingdom of Great Britain and Northern Ireland
Practice Relating to Rule 29. Medical Transports
Section A. Respect for and protection of medical transports
The UK Military Manual (1958) provides: “Vehicles equipped for the transport of wounded and sick, as well as their medical equipment, must be respected and protected in the same way as mobile medical units.” 
United Kingdom, The Law of War on Land being Part III of the Manual of Military Law, The War Office, HMSO, 1958, § 356.
The manual further states: “Convoys of vehicles or hospital trains on land … conveying wounded and sick civilians, the infirm, and maternity cases must be protected and respected in the same way as civilian hospitals.” 
United Kingdom, The Law of War on Land being Part III of the Manual of Military Law, The War Office, HMSO, 1958, § 33.
The UK LOAC Pamphlet (1981) provides: “Protection from attack is given … to medical transport, e.g. ambulances”. 
United Kingdom, The Law of Armed Conflict, D/DAT/13/35/66, Army Code 71130 (Revised 1981), Ministry of Defence, prepared under the Direction of The Chief of the General Staff, 1981, Section 6, p. 23, § 8(a).
The UK LOAC Manual (2004) states:
7.12. Medical transport means any means of transportation, whether military or civilian, permanent or temporary, assigned exclusively to the conveyance by land, water or air of the wounded, sick, shipwrecked, medical or religious personnel, medical equipment or medical supplies protected by the Geneva Conventions and Additional Protocol I and under the control of a competent authority of a party to the conflict. In Additional Protocol I, reference to “medical vehicles” expressly means “any medical transports by land”. Similarly, “medical ships and craft” means “any medical transports by water” and “medical aircraft” means “any medical transports by air”.
7.12.1. The assignment to medical purposes must be exclusive, although it may be permanent or temporary. The word “exclusive” is intended to restrict the definition of medical transport and its use so that the essential protection will not be eroded by abuses. “Permanent” means for an indeterminate period; “temporary” means limited periods but devoted exclusively to medical tasks during the whole of such periods.
Protection of Medical Units
7.13. Medical units are to be “respected and protected at all times and shall not be the object of attack.” Medical units, personnel and transport must not be used for non-medical purposes, otherwise their protection will be jeopardized. In addition, medical units must not “be used in an attempt to shield military objectives from attack” and, where possible, should be so sited that attacks against military objectives do not imperil their safety. The improper use of medical units to kill, injure or capture the enemy amounts to the war crime of perfidy.
7.13.1. Medical units are given this general protection to enable them to perform their humanitarian functions. Thus, the protection given to medical units ceases if “they are used to commit, outside their humanitarian function, acts harmful to the enemy”. Protection may only be withdrawn, however, after due warning has been given, setting, whenever appropriate, a reasonable time limit and after such warning has remained unheeded. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, §§ 7.12–7.13.1.
With regard to internal armed conflict, the manual states:
15.29. It is prohibited to attack:
c. medical buildings, including hospitals and places where the wounded and sick are cared for, medical material, medical units, and transport.
15.29.1. The wounded, sick, and shipwrecked must be protected … Medical units, personnel and transports must be protected from attack and are entitled to display the protective emblem of the red cross or red crescent on a white background.
15.47. Medical units and transports “shall be respected and protected at all times and shall not be the object of attack”. However this protection may cease if “they are used to commit hostile acts, outside their humanitarian function”. Even then, the protection will only cease “after a warning has been given setting, whenever appropriate, a reasonable time limit, and after such warning has remained unheeded”. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, §§ 15.29–15.29.1 and 15.47.
At the CDDH, the United Kingdom welcomed “the humanitarian advances made in such fields as medical aircraft, the extension of protection to a wider group of medical units and transports and the improved provisions on relief”. 
United Kingdom, Statement at the CDDH, Official Records, Vol. VII, CDDH/SR. 58, 9 June 1977, p. 302, § 114.