Related Rule
Practice Relating to Rule 5. Definition of Civilians
In 2010, in the Fuel Tankers case, the Federal Prosecutor General at Germany’s Federal Court of Justice investigated whether war crimes or other crimes under domestic law had been committed in the course of an airstrike which was ordered by a colonel (Oberst) of the German armed forces against two tankers transporting fuel for the International Security Assistance Force in Afghanistan stolen by the Taliban near Kunduz and which resulted in the deaths of a number of civilians. The Federal Prosecutor General stated:
Pursuant to § 170 para. 2 StPO [Penal Procedure Code], the investigation proceedings which were initiated by the order of 12 March 2010 against Colonel (Oberst) Klein and Company Sergeant Major (Hauptfeldwebel) Wilhelm due to suspected offences under the VStGB [International Crimes Code] and other offences are to be terminated as a result of the investigations conducted and based on the sources of information set out hereafter and on the reasons given in detail hereafter. 
Germany, Federal Court of Justice, Federal Prosecutor General, Fuel Tankers case, Decision, 16 April 2010, p. 1.
The Federal Prosecutor General considered the definition of “civilians” in non-international armed conflict in the context of § 11(1)(3) of Germany’s International Crimes Code which states that carrying out an attack by military means and definitely anticipating that the attack will cause death or injury to civilians or damage to civilian objects on a scale out of proportion to the concrete and direct overall military advantage anticipated is a war crime in international and non-international armed conflict. The Federal Prosecutor General stated:
The following is to be considered regarding the subjective element of § 11 (1) (3) VStGB [International Crimes Code]:
Insurgents who continuously take part in the armed conflict, as the Taliban in this case, are not civilians but legitimate military objectives which may be lawfully attacked even outside of ongoing armed hostilities. Art. 50 (1) AP I [1977 Additional Protocol I] contains a definition of the term “civilian” for international armed conflicts. Accordingly any person “who does not belong to one of the categories of persons referred to in Art. 4 paragraph A sub-paragraphs (1), (2), (3) and (6) of the [1949 Geneva] Convention III and in Article 43 of this Protocol is a civilian”. Therefore members of armed forces or of organized armed groups (militias and volunteer corps) of a party to the conflict and of a levée en masse are not civilians … They often have a regular full-time or part-time civilian job (“farmer by day, fighter by night”). Nevertheless they are not considered as civilians under current international law who only assume the role of a fighter during the limited duration of ongoing armed hostilities and constitute a lawful military objective during such time only. … The opinion previously expressed in the literature according to which they are to be considered as civilians who may only be attacked during their participation in hostilities … is to be considered as a minority opinion which has not been representative at least since the publication of the Interpretative Guidance of the International Committee of the Red Cross in June 2009 … State practice in non-international armed conflict never reflected this opinion and in addition it is not reconcilable with the principle of distinction which is generally recognized as customary international law …
The fuel tankers had been abducted by an organized group of armed Taliban whose members were thus not civilians. 
Germany, Federal Court of Justice, Federal Prosecutor General, Fuel Tankers case, Decision, 16 April 2010, pp. 47–48; see also p. 60.