Military necessity

Abstract

It is often said that international humanitarian law (IHL) “accounts for” military necessity, but its meaning and normative consequences have remained obscure. This thesis develops a theory that offers a coherent explanation of the process through which IHL generates its rules.

To planners, commanders and historians concerned with the effectiveness of fighting, military necessity embodies a truism that it is in each belligerent’s self-interest to maximise successes and minimise failures. To those concerned with articulating IHL standards of behaviour, military necessity offers weighty reasons for which the belligerent should be left at liberty to pursue necessities and avoid non-necessities – or to forgo opportunities and commit blunders at its own peril. To judges, observers and others concerned with IHL compliance, military necessity functions as a ground on which deviant conduct may sometimes be exempt from the main rule.

In none of these contexts does military necessity obligate necessary acts or prohibit unnecessary ones. Rather, it permits any belligerent action. Military necessity’s normative indifference means that it never affirmatively conflicts with humanitarian considerations, despite suggestions to the contrary. It also invalidates the popular idea that conduct in conformity with positive IHL rules becomes unlawful if it lacks military necessity.