WAR HAS always had rules, even if only to protect the dead. In The Iliad, for example, Homer tells us that Achilles' desecration of Hector's corpse angered the gods. Medieval churchmen sought to limit warfare to certain days of the week and evolved an entire just war theology to constrain the use of armed force. By the Age of Reason, international law "publicists" were busily expounding on the subject, and the 20th century opened with a substantial body of law governing both the right to initiate combat (jus ad bellum) and how armed force is applied (jus in bello). These "laws of war" were based both on custom and treaties and were accepted by all of the Great Powers--including the United States. In more recent years, however, fissures have opened between America and Europe over what the laws of war require with respect to when it is permissible to launch an armed attack, how warfare must be waged, and how the relevant legal norms should be enforced. Today, these disagreements are so fundamental that America and its partners in Europe can be said to operate under different legal codes.
The core of this divergence can be traced to efforts--largely initiated during the Vietnam War era--both to leash the dogs of war and make the laws of combat more humane by mimicking the rules governing domestic police activities, in which deadly force is always the last resort and must not be applied in an "excessive" manner. In the process, "humanitarian" concerns were to be elevated above considerations of military necessity and national interest.
These efforts have taken the form of multilateral conventions, such as the 1977 Protocol I Additional to the 1949 Geneva Conventions (Protocol I) or the 1997 Ottawa anti-landmine convention, and of new interpretations of existing treaties (such as the UN Charter), or of customary norms. Although the United States helped to negotiate a number of these treaties, it has steadfastly rejected the most sweeping innovations, favoring instead more traditional jus ad bellum and jus in bello norms. In particular, the United States has clearly asserted that it will use force, where necessary, to defend its interests with or without UN Security Council approval, and has rejected agreements that could be interpreted as contrary to key aspects of U.S. military doctrine.
This reticence is not part of a nefarious American effort to achieve immunity from international law, as critics have sometimes asserted. Unlike many countries, which embrace new international conventions with little intent to comply thereafter, the United States has always taken its obligations seriously--refusing, for example, to ratify treaties it does not plan to implement, whether because of policy or constitutional concerns. What the critics fail to realize is that binding international legal obligations must be based on the consent of the affected states. They cannot be imposed. In eschewing many of the new international legal norms accepted by Europe, the United States has simply acted within its legal rights as an independent sovereign.
Nor does the American refusal to follow Europe's lead in this area stem from any lack of humanitarian zeal. Rather, it can be traced to recognition by the United States that the world remains a dangerous place, and that adoption of a "policing" model for warfare would hamper, if not cripple, America's ability to defend itself--and its allies. Peacetime norms, which guide the conduct of police and security establishments in modern democracies, are far more restrictive than the laws of war because they operate in an environment in which the state has an effective monopoly on the lawful use of force, and in which the damage that any single individual or group can inflict is limited. The laws of war, by contrast, apply in a context in which the state does not have a monopoly on either the lawful right to use force or on the use of the most destructive weapons. War …