In my first article examining the legality of assassinating known or suspected terrorists through the use of unmanned armed vehicles (UAVs), I argued that the first step is to decide whether such killings could be classified as part of an armed conflict. If they are considered as part of an armed conflict, according to international law, the rules of armed conflict would apply; otherwise the laws of self-defence would be relevant.
According to the Geneva Conventions and customary humanitarian law, armed conflict only applies when two or more States are involved. When the United States defines its campaign against terrorists as a global conflict, this designation is not based on the correct definition of war as characterized by international law but on America's own interpretation of its effort to eradicate terrorism. Only two or more States can legally, in the strictest terms, engage in war, not a State against individuals scattered around the globe.
The international laws relating to self-defence apply to the case where a State is seeking to protect itself from a group or groups of terrorists. The laws of self-defence are articulated in the seventh chapter of the United Nations Charter. In Chapter 7, Article 51, it states that: "Nothing in the present Charter shall impair the inherent right of individual or collective self-defence if an armed attack occurs..Measures taken by members in the exercise of the right of self-defence shall be immediately reported to the Security Council and shall not"affect the authority or responsibility of the Security Council"to take such action"to maintain or restore international peace and security."
In analyzing this clause in the UN Charter, the overriding issue is whether this right of self-defence only exists if an armed attack has occurred or whether self-defence is legitimate under conditions of "anticipatory self-defence" or "pre-emptive self-defence".
A precedent exists in customary law in the Caroline case which established that an "imminent threat" exists when it is "instant, overwhelming, and leaving no choice of means, and no moment for deliberation." Developed by Daniel Webster, these criteria legitimize the use of force in the absence of an act of aggression.
There is an extensive body of work seeking to define when the use of force is legitimate given an imminent threat including the argument that: "The rule does not actually require an attack to be imminent to act, but rather permits defensive measures to be taken before one passes a point in time when it is too late to prevent catastrophe.
It is difficult to argue that the threat extended by a single or group of terrorists poses a threat to the security of the United States. It could be argued that terrorist poses a threat to individuals or to property belonging to the United States in which case criminal law applies and the response requires police action not an armed attack by a State.
A further point reinforcing the argument of a police action is that these targets of drone attacks are suspects until due process condemns them for criminal acts. Killing the suspect precludes the application of due process.
It is clearly evident that for a State to launch an attack by an UAV is a violation of international law and those responsible for such acts become suspects of war crimes. Arbitrary killing of individuals around the world notwithstanding the justification cannot be in accordance with the rule of law under which certain norms of behaviour have been established for the treatment of individuals suspected of illegal acts.