The Legal Fog Between War and Peace FOR all the heated back and forth over the acceleration of America's targeted killings campaign, which took out Abu Yahya al-Libi, the No. 2 man in Al Qaeda, last week, the program's lawfulness turns on one simple question: Are we at war? Try to answer that question, however, and the simplicity falls away. In the skies over Afghanistan and Pakistan, the basic distinction between war and peace - the foundation of laws of armed conflict that have been evolving for three centuries - is in collapse. Under current law, the legal analysis of targeted killings is straightforward: If we are at war, an American government may target enemy combatants and civilians directly participating in hostilities without running afoul of either domestic or international law. Such killings are not assassinations because they are lawful. It was lawful when the Continental Army singled out British officers for fire, and when the United States Navy, on the order of Navy Secretary Frank Knox, targeted and killed Adm. Isoroku Yamamoto, Japan's premier naval commander, over the Pacific in World War II. If we are engaged in a peacetime law enforcement operation, by contrast, targeted killings are almost certainly illegal under both domestic and international law. The criminal justice system allows government officials to target and kill only when doing so is required for self-defense or for the defense of others, and when there is no reasonable opportunity to capture the person instead. End of story. Those legal categories, however, no longer fit the events we are experiencing. The war paradigm now seems an indefinite grant of dangerously vast authority to the president. The law enforcement paradigm, by contrast, threatens to tie the hands of the country in an era of unconventional weapons and potential nuclear proliferation. In fact, our arguments about targeted killings are playing out at a historic juncture in which the categories of war and peace, which the modern world thought it had carefully separated, are collapsing into each other. Until the modern era, European armies treated unjust wars as a form of criminal behavior. A righteous soldier like Henry V at Agincourt in 1415 could execute or enslave an enemy prisoner because an unjust enemy was like anyone who unjustly employed force against another person: a criminal. The difficulty was that, human nature being what it is, virtually all soldiers imagined that theirs was the side of justice. And so, during the Enlightenment, legal experts transformed the law of war by adopting a posture of startling moral modesty: they stipulated that all sovereign states in armed conflict would be treated as if they were fighting on the side of justice, even though the truth of that assertion was disputed. That's why a uniformed soldier of one state who shoots at the soldiers of another commits no crime, even when he does so in the name of an unjustifiable cause. The separation between war and peacetime law enforcement immunizes soldiers from culpability, so long as their acts comport with the rules of combat. In the centuries since, an entire apparatus of those rules has been built atop the separation of war and peace. With so much resting on the distinction, it should be no surprise that the line between war and peace has often been disputed. British commanders insisted that the American War of Independence was no war at all - and that patriot soldiers were thus criminal rebels - until very near the end of the conflict. Andrew Jackson treated Seminole Indians as incapable of engaging in civilized warfare. And in the Civil War, Lincoln shifted back and forth between treating the conflict as a war - notably, in regard to prisoners and the blockade of the South - and as a treasonous criminal conspiracy. In the Indian wars of the late 19th century, American generals treated the conflicts alternately as armed hostilities and as law enforcement operations, as it suited them. Today, war and law enforcement are merging. America's armed forces often behave like police departments. They conduct pervasive surveillance against small clusters of men who cannot hope to stand up to American firepower. In the law as well, the line between war and peace has been blurred. Our enemies are often subject to prosecution as unlawful combatants; just last month, military commission proceedings began at Guantánamo Bay in the case of Khalid Shaikh Mohammed and four co-defendants for their involvement in the 9/11 attacks. Meanwhile, the International Criminal Court is also reasserting the concept of crime and punishment in war. It recorded its first verdict in March when it convicted the Democratic Republic of Congo warlord Thomas Lubanga of the war crime of using child soldiers. The International Committee for the Red Cross even interprets humanitarian law as urging a responsibility not to kill but instead to capture enemies in war when feasible - a shift that would dramatically alter the traditional balance between war and peace. Current international law purports to decide the question of war or peace by evaluating the intensity of the conflict. But in an age of mass destruction, when conflicts can go in an instant from zero intensity to unfathomable terror, the intensity measure seems ill suited to the work at hand. What we need is not anxiety over targeted killings but a third way between the longstanding models of war and peace. Movement in this direction is already under way. Nongovernmental organizations and the media have brought targeted killings to the light of day. Inside the United States government, lawyers like Jeh C. Johnson in the Pentagon and Harold H. Koh in the State Department, along with hundreds of other lawyers in the Justice Department, the White House and elsewhere, are creating new systems for regulating the targeting process. At the same time, constitutional lawyers have begun thinking through the problem of executive branch power, experimenting with proposals ranging from strengthening the Justice Department or the White House counsel's office to instituting a legal tribunal within the executive branch. Few permanent fixes have emerged yet. Three hundred years of history make for difficult work. But the difference between war and peace is a matter of urgency, for this much is certain: the awesome technology of the armed drone is ours and ours alone only temporarily. History's lesson is that what we employ against Abu Yahya al-Libi now will soon be available for use by our adversaries. When that happens, we will desperately want the credibility to judge their actions. John Fabian Witt is a professor of law and history at Yale Law School and the author of the forthcoming "Lincoln's Code: The Laws of War in American History."