Related Rule
Germany
Practice Relating to Rule 28. Medical Units
Germany’s Military Manual (1992) provides:
612. Fixed medical establishments … and mobile medical units of the medical service shall under no circumstances be attacked. Their unhampered employment shall be ensured at all times. As far as possible, medical establishments and units shall be sited or employed at an adequate distance to military objectives
613. [Fixed medical establishments, vehicles and mobile medical units of the medical service] shall not be used to commit acts harmful to the enemy.
618. Medical establishments which contrary to their intended purpose are used to carry out acts harmful to the enemy may lose their protection after prior warning has been given.
619. To this effect, the following acts shall not be considered as hostile acts:
–that medical personnel use arms for their own protection, and that of the wounded and sick;
–that medical personnel and medical establishments are protected by sentries or an escort;
–that medical personnel are employed as sentries for the protection of their own medical establishments; and
–that war material taken from the wounded and sick is retained. 
Germany, Humanitarian Law in Armed Conflicts – Manual, DSK VV207320067, edited by The Federal Ministry of Defence of the Federal Republic of Germany, VR II 3, August 1992, English translation of ZDv 15/2, Humanitäres Völkerrecht in bewaffneten KonfliktenHandbuch, August 1992, §§ 612-613 and 618-619; see also § 616 (property of aid societies).
Germany’s IHL Manual (1996) states:
Fixed medical establishments … and mobile medical units of the medical service shall under no circumstance be attacked. Their unhampered employment shall be ensured at all times. As far as possible, medical establishments and units shall be sited or employed at an adequate distance to military objectives. 
Germany, ZDv 15/1, Humanitäres Völkerrecht in bewaffneten Konflikten – Grundsätze, DSK VV230120023, Bundesministerium der Verteidigung, June 1996, § 503.
The manual further states that fixed medical establishments, vehicles and mobile medical units of the medical service “shall not be used to commit, outside their humanitarian function, acts harmful to the enemy”. 
Germany, ZDv 15/1, Humanitäres Völkerrecht in bewaffneten Konflikten – Grundsätze, DSK VV230120023, Bundesministerium der Verteidigung, June 1996, § 503.
Germany’s Soldiers’ Manual (2006) states: “Fixed establishments, vehicles and mobile units of the medical service, without exception, may not be fought. Their unhampered employment shall be ensured at all times.” 
Germany, Druckschrift Einsatz Nr. 03, Humanitäres Völkerrecht in bewaffneten Konflikten – Grundsätze, Erarbeitet nach ZDv 15/2, Humanitäres Völkerrecht in bewaffneten Konflikten – Handbuch, DSK SF009320187, Bundesministerium der Verteidigung, R II 3, August 2006, p. 5.
Germany’s Law Introducing the International Crimes Code (2002) punishes anyone who, in connection with an international or non-international armed conflict, “carries out an attack against … medical units and transport designated with the distinctive emblems of the Geneva Conventions … in conformity with international humanitarian law”. 
Germany, Law Introducing the International Crimes Code, 2002, Article 1, § 11(1)(2).