This Article answers two of the most urgent and important questions facing the contemporary law of armed conflict. First, how certain must a soldier be that a given individual is a combatant and not a civilian before attacking that individual? Second, what risks must soldiers accept to themselves and to their mission in order to reduce the risk of mistakenly killing civilians?
In the absence of clear legal rules, leading states, scholars, and practitioners have embraced a “Balancing Approach” according to which both the required level of certainty and the required level of risk vary with the balance of military and humanitarian considerations. However, this Article shows that the Balancing Approach ignores the moral asymmetries between killing and letting die and between intentionally and unintentionally killing civilians. As a result, in a wide variety of situations, the Balancing Approach would permit soldiers to intentionally kill individuals who are either probably, much more likely, or almost certainly civilians rather than combatants. These implausible implications expose the fatal defects of the Balancing Approach and demonstrate the need for a morally defensible alternative.
To meet this need, this Article develops a deontological account of both the required level of certainty and the required level of risk. The first part of this new account, “Deontological Targeting,” prohibits a soldier from intentionally killing an individual if the soldier believes the individual is a civilian, or if the soldier does not reasonably believe the individual is a combatant. These constraints establish a minimum threshold of certainty that soldiers must reach before using deadly force. Above the reasonable belief threshold, the required level of certainty varies with the relative costs of error but, crucially, also reflects the moral asymmetry between killing and letting die. In particular, except in rare cases, targeted killing operations against individuals who pose no immediate threat are permissible only if there is conclusive reason to believe that the individuals are combatants.
The second part of this new account, “Deontological Precaution,” requires, at a minimum, that soldiers take as much risk as necessary to reach the required level of certainty. In addition, soldiers must take further precautions unless doing so would increase the risk to the soldiers substantially more than doing so would decrease the risk to civilians. If soldiers are unwilling or unable to reach the required level of certainty or accept the required level of risk then they must hold their fire. The Article concludes by distilling these complex moral principles into new legal rules, reinterpretations of existing legal rules, and model rules of engagement in which soldiers can be trained and that can guide soldiers through the fog of war.