The Obama administration has reportedly been trying to come up with a set of rules to govern its campaign of targeted killing by drones. Though officials had hoped to complete it before the November presidential election, just in case Mitt Romney won, there's apparently so much ongoing internal controversy over the appropriate rules governing when the United States can kill someone overseas without so much as a warrant, let alone judicial review, that the administration still hasn't been able to agree on a rulebook. According to the New York Times: "Mr. Obama and his advisers are still debating whether remote-control killing should be a measure of last resort against imminent threats to the United States, or a more flexible tool, available to help allied governments attack their enemies or to prevent militants from controlling territory." In fact, international law already answers that question. Administration officials repeatedly insist they follow the law. It should be the backbone of their new rulebook. Under international law, in an armed conflict the United States can kill members of the armed forces of the enemy, or civilians while they directly participate in hostilities. Beyond an armed conflict, the U.S. can only use lethal force consistent with international human rights law: in response to an imminent threat to human life that cannot be mitigated otherwise. In Afghanistan, the United States is still clearly in an armed conflict. But where else does the law of armed conflict apply? Only where the United States is fighting a definable, centrally-organized enemy with a continuous intensity of violence that is clearly beyond sporadic attacks. It does not apply to an amorphous "war on terror" against loosely-affiliated insurgent groups abroad who may be fighting their own governments. The United States can intervene in such a conflict, say, on behalf of the government of Yemen, but as a matter of democratic principle, the U.S. government ought to be telling Americans if that's what it's doing. The problem with the drone war is that so far, U.S. officials haven't told us much of anything. Is the United States in a war with al Qaeda in the Arabian Peninsula or AQAP, in Yemen? Or are the U.S. drones there merely killing people on behalf of the Yemeni government, which is battling several different armed factions opposing its rule? Does the CIA have information that any of the people it's killing actually pose an imminent threat to human life, or are its targets merely suspected bad guys who populate a "kill list"? And if they're on a "kill list," can whatever threat they pose really be imminent? These are the questions that the United States government should be answering. And any new rulebook needs to incorporate all of the actual rules already provided by widely-accepted international law. Sure, applying the rules will sometimes be complicated. But no one ever said that remote killing of suspected insurgents in other countries should be easy. Continued U.S. secrecy about the program's rules is bad for democracy. The American people need to know what standards are in place for their government to kill without charges or trial. Secrecy is also bad for national security. The more the U.S. keeps its rules secret, the more latitude some countries are going to claim we're taking, and they're entitled to. Other countries are skeptical of U.S. targeting policies and, as a result, withhold counterterrorism cooperation from the United States. Increased transparency may cause them to conclude that the U.S. is in compliance with international law. In light of this, the United Nations has announced it's opening a new unit next year to investigate U.S. drone strikes and determine whether, in its view, they're being conducted legally. The U.S. government should cooperate with that investigation. But before it even gets started, Obama administration officials should settle their conflict and make clear they've come down on the side of long-held principles of international law. Attempting to circumvent the rules by creating new ones that are incompatible with international law will sounds a lot like the Bush administration, which wrote legal memos to justify torture. That backfired and created an indelible stain on American credibility in standing up for human rights anywhere in the world. This administration should not repeat that mistake.