Introduction -- I. Concept, history and basics -- Elements of military necessity -- Military necessity and its history -- Assessing military necessity through a military margin of appreciation -- Assessing necessity and criminal responsibility -- Military necessity and humanitarian considerations -- II. Distinction as limitation upon military necessity in the law of armed conflict -- The principle of distinction : also a limitation upon military necessity -- Military objects -- Combatants as lawful targets -- Military necessity and the notion of 'law combatancy' -- Who are civilians and when do they lose their protection? -- III. Effectuating distinction : enforcing an ultimate balance between necessities of war and considerations of humanity -- Protection of the civilian population and perceptions of military necessity -- Military necessity and proportionality -- Military necessity and the scope and nature of military advantage -- The commander's ultimate 'margins' : assessing excessiveness and feasibility -- IV. The exceptive face of military necessity -- Destruction and seizure of property when military necessity requires -- Military necessity and rules on special protection -- V. Conclusions -- Conclusions : limitations to the commander's assessment of military necessity.