INTRODUCTION

In November 2001, in the first few months of the war on terrorism, US and UK forces in Afghanistan, together with the Northern Alliance, rounded up more than 400 Taliban and suspected al-Qaeda fighters and brought them to the Qala-i-Jangi fortress outside of Mazar-i-Sharif. They neglected to disarm the prisoners completely, and in the midst of some initial interrogation procedures, some of the detainees detonated some grenades, seized weaponry and rioted. In response, airstrikes were called in, and over the next twelve hours they proceeded to bomb the prison relentlessly, eventually killing all 400 prisoners. A few days later, US Secretary of Defense Donald Rumsfeld was asked, during his daily press briefing, whether the response might have been ‘disproportionate’. He replied:

Despite Rumsfeld's confusion, the idea of proportionality is one of the oldest and most central concepts of just war theory, and has long been formalised in both the law of armed conflict and military strategy. Along with the requirement of discrimination between combatants and noncombatants, ‘proportionality’ attempts to make the violence of war proportionate to the threat it is meant to overcome, and make the unintended mistakes of a war proportionate to their intended benefits. Proportionality figures prominently in judgements about the justice of a war itself, jus ad bellum, and the justice of the means employed, jus in bello. It is also used in thinking about punishment, including issues of post-conflict justice or jus post bellum.