Related Rule
Germany
Practice Relating to Rule 17. Choice of Means and Methods of Warfare
Germany’s Military Manual (1992) states: “Before engaging an objective, every responsible military leader shall … choose means and methods minimizing incidental injury and damage to civilian life and objects.” 
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 Konflikten – Handbuch, August 1992, § 457.
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 further stated:
IV. Facts
3.
Colonel (Oberst) Klein gave Company Sergeant Major (Hauptfeldwebel) Wilhelm the order to make the aircraft personnel undertake the usual so-called Weaponeering and Targeting. This involves checking the scope of the impact of the available weapons and to render it visible on the video pictures by drawing an ellipsis. The aircraft was carrying 500 pound bombs and 2,000 pound bombs. From the very beginning Colonel (Oberst) Klein excluded the use of 2,000 pound bombs because they might have affected the nearby farm building. Colonel (Oberst) Klein ordered the JTAC [Joint Terminal Attack Controller] to find out which weapons would be necessary to fight the fuel tankers and the Taliban in their surroundings. He received the information from the aircraft crew that six 500 pound bombs, which should detonate at a certain distance from the ground, would be required. Colonel (Oberst) Klein and the JTAC considered this quantity structure as completely excessive. At this point a decision on the use of weapons was not yet made.
4.
… [Subsequently, Colonel (Oberst) Klein] gave Company Sergeant Major (Hauptfeldwebel) Wilhelm the order to coordinate the use of weapons with the pilots with the objective of minimizing the weapons’ impact and to strictly limit their impact to the fuel tankers, the insurgents surrounding the tankers but under no circumstances beyond the sandbank. After discussing the proposals of the aircraft crew and the JTAC he came to the conclusion that the smallest possible impact of the weapons suitable to destroy the two fuel tankers could be achieved by dropping one 500 pound bomb on each of the two vehicles. Moreover, Colonel (Oberst) Klein decided to drop the bombs by using a delayed detonation mechanism in order to reduce their cluster effect so that the danger of killing or injuring the persons not in direct proximity of the fuel tankers was as low as possible. 
Germany, Federal Court of Justice, Federal Prosecutor General, Fuel Tankers case, Decision, 16 April 2010, pp. 22–24.
The Federal Prosecutor General further stated:
Criminal responsibility under § 211 StGB [i.e. for murder under Germany’s Penal Code]
b)
Colonel (Oberst) Klein’s actions were lawful under international law and therefore justified under domestic criminal law …
cc)
Even considering the fact that the bombing killed civilians to be protected under the international law of armed conflict, the order to attack was lawful under international law.
(5)
In addition to the obligation to respect military proportionality, the international law of armed conflict includes the obligation to use means of warfare which could affect civilians as sparingly as possible (Obligation to use the mildest means, see Art. 57 para. 2 sub-para. a (ii) AP [the 1977 Additional Protocol] I …).
Also in this respect the perpetrator’s perspective when undertaking his assessment at the time must be assumed. As stated above, this perspective was characterized by Colonel (Oberst) Klein justifiably assuming that no civilians were present. It is only added subsidiarily that if the presence of civilians had been assumed the obligation to use the mildest possible means would not have been violated. Prior to dropping the bombs, Colonel (Oberst) Klein discussed at length with the air-traffic control officer (Flugleitoffizier) and the pilots whether a milder means would suffice to achieve the objective.
Contrary to the pilots’ further reaching proposals, Colonel (Oberst) Klein decided to employ the smallest available bomb size (500 pounds) and to make use of the delayed trigger mechanism which reduces the scope of the bomb’s impact. A violation of the principle of the mildest possible means can therefore be excluded. 
Germany, Federal Court of Justice, Federal Prosecutor General, Fuel Tankers case, Decision, 16 April 2010, pp. 59–67.