Imagine that you are a soldier, fighting in an irregular armed conflict against a non-uniformed enemy that intermingles with the civilian population. Imagine that your unit is under fire and that you see an individual standing on a nearby roof talking on a cell phone. He may be a spotter or a lookout calling in your location, or he may be a bystander warning his family to stay out of harm's way. Now imagine that you are remotely piloting an Unmanned Aerial Vehicle (a "drone"), and on your video monitor you see a group of armed men riding on the back of a truck. These men may be members of an implacable insurgency or merely locals carrying arms for their own protection in a dangerous area. Finally, imagine that you are the President of the United States and that a team of intelligence analysts informs you that they are "between forty and sixty per cent" confident that Al Qaeda leader Osama bin Laden is living in a residential compound in Abbottabad, Pakistan, surrounded by civilians. (1)
What would you do? What may you lawfully do? What should you ethically do? How certain must you be that someone is a combatant (more precisely, a legitimate target) rather than a civilian (more precisely, an illegitimate target) before using lethal force? I believe these are among the most difficult and important questions in the law and ethics of armed conflict. I also believe that these questions have answers.
The relevant legal rules are suggestive but unclear, and have been widely interpreted in ways that are morally indefensible. For example, Additional Protocol I to the Geneva Conventions states that "[i]n case of doubt whether a person is a civilian, that person shall be considered to be a civilian." One might think this means that a soldier must be certain beyond a reasonable doubt that someone is a combatant before attacking her. But this is not how the rule has been received or interpreted. For example, the International Committee of the Red Cross, one of the world's leading expositors of international humanitarian law, writes the following:
Obviously, the standard of doubt applicable to targeting decisions cannot be compared to the strict standard of doubt applicable in criminal proceedings but rather must reflect the level of certainty that can reasonably be achieved in the circumstances. In practice, this determination will have to take into account, inter alia, the intelligence available to the decision maker, the urgency of the situation, and...