Related Rule
Germany
Practice Relating to Rule 4. Definition of Armed Forces
Germany’s Military Manual (1992) states:
The armed forces of a party to a conflict consist of all its organized armed forces, groups and units. They also include militias and voluntary corps integrated in the armed forces. The armed forces shall be:
–under a command responsible to that party for the conduct of its subordinates, and
–subject to an internal disciplinary system which, inter alia, shall enforce compliance with the rules of international law applicable in armed conflict. 
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, § 304.
In an explanatory memorandum submitted to the German Parliament in 1990 in the context of the ratification procedure of the Additional Protocols, the German Government stated that the 1977 Additional Protocol I contained the first treaty definition of the term “armed forces” and acknowledged that armed forces must be organized, under responsible leadership and have an internal disciplinary system. 
Germany, Lower House of Parliament, Explanatory memorandum on the Additional Protocols to the Geneva Conventions, BT-Drucksache 11/6770, 22 March 1990, p. 110.
Germany’s Military Manual (1992) states:
Whenever a party to a conflict incorporates a paramilitary or armed law enforcement agency into its armed forces it shall notify the other parties to the conflict. In the Federal Republic of Germany the Federal Border Commands including their Border Guard formations and units as well as the Federal Border Guard School shall become part of the armed forces upon the outbreak of an armed conflict. 
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, § 307.
The Report on the Practice of Germany (1997) notes that from 1965 to 1994, German border guards were granted the status of combatants. In 1994, the German Parliament adopted a law that changed the status of the border guards. The reason for this change was that, as combatants, these guards could become legitimate enemy targets and they could involve local police forces as targets when operating in joint action. In addition, even civilian objects protected by the police might become targets. 
Report on the Practice of Germany, 1997, Chapter 1.1, referring to Federal Border Police Law, 1994, Article 4.