On Thursday, 11 May 2017, Nobuo Hayashi will defend his PhD dissertation entitled “Military Necessity” at Leiden University’s Academy Building (Rapenburg 73). He will argue that military necessity denotes normative indifference in international law.
Two influential views on military necessity exist under today’s international humanitarian law (IHL). According to one, IHL prohibits all acts lacking in military necessity. They become unlawful simply because they are militarily unnecessary, even if they do not violate any of the law’s specific rules.
The other holds that military necessity and humanity inevitably conflict with each other. Since IHL already embodies a compromise between them, neither pleas are admissible vis-à-vis its unqualified rules.
Hayashi challenges both positions and develops a new, contextualised theory.
Military Necessity as Indifferent Permission
Military necessity gives the framers of IHL rules cause to do two things. First, it prompts them to consider permitting the belligerent to do what is necessary and avoid what is unnecessary. Second, military necessity prompts the framers to consider leaving the belligerent at liberty to imperil itself by forgoing opportunities and encumbering itself with blunders.
It follows that military necessity in IHL neither obligates nor prohibits. Rather, it merely – and indifferently – permits. IHL framers have no reason to make acts mandatory because of their necessity, or to outlaw acts because of their non-necessity. Although IHL endeavours to accommodate the pursuit of military necessities, the law does not make it its business to save incompetent belligerents from themselves.
Military necessity’s normative indifference also means that it is never in conflict with humanity. Where humanity demands what military necessity permits, it always remains open to the belligerent to act in a manner that jointly satisfies them. Even where humanity condemns what military necessity permits, the belligerent can still satisfy both by acting in accordance with humanity.
Unqualified IHL rules exclude all pleas for deviant behaviour that emanate from indifferent considerations, including military necessity. The situation is arguably different where pleas emanate from considerations that are not indifferent. Though humanity sometimes exhibits indifference, it often demands actions and condemns others. It is possible that humanitarian imperatives modify an act’s lawfulness over and above the law’s unqualified rules.
Military Necessity in Its Material, Normative and Juridical Contexts
In its strictly amoral context, military necessity separates war-fighting that is effective and conducive to success from that which is neither. The notion merely entails the truism that it is in each belligerent’s strategic self-interest to maximise success and minimise failures.
Military necessity’s normative indifference becomes most apparent in the context of IHL norm-creation.
Juridically, military necessity exempts conduct from certain IHL rules that principally prescribe contrary behaviour. Such conduct must show, cumulatively, that it was performed primarily for some specific military purpose; that it was required for the purpose’s attainment; that the purpose sought was in conformity with IHL; and that the conduct itself was otherwise in conformity with IHL.
Some war crimes and crimes against humanity are built on substantive IHL rules that admit military necessity exceptions. ICTY rulings on the matter have so far been largely competent. The Rome Statute contains provisions that are vulnerable to abuse as backdoors through which defendants may improperly seek to justify or excuse crimes based on military necessity.