"Imminence" used to mean something in military terms: namely, that an adversary had begun preparations for an assault. In order to justify his drone strikes on American citizens, President Obama redefined that concept to exclude any actual adversary attack.

That's the heart of the Justice Department's newly leaked white paper, first reported by NBC News, explaining why a "broader concept of imminence" (.pdf) trumps traditional Constitutional protections American citizens enjoy from being killed by their government without due process. It's an especially striking claim when considering that the actual number of American citizens who are "senior operational leader[s] of al-Qaida or its associated forces" is vanishingly small. As much as Obama talks about rejecting the concept of "perpetual war" he's providing, and institutionalizing, a blueprint for it.

Imminence has always been a tricky concept. It used to depend on observable battlefield preparations, like tanks amassing near a front line, missile assemblage, or the fueling of fighter jet squadrons. Even under those circumstances, there has been little international consensus about when a nation under threat can take action. A classic example is Israel's June 1967 bombing of the Egyptian Air Force on its tarmac, which followed months of signals that Egypt was about to launch a massive assault. Whether you view Israel or Egypt as the aggressor tends to depend on your sympathy to either party in the conflict.

President George W. Bush contended that the U.S. had to invade Iraq not because the government knew Saddam Hussein was about to launch an attack on America, but because it didn't. Bush contended that uncertainty about Saddam's weapons of mass destruction, augmented by 9/11's warnings of shadowy terrorist groups plotting undetectable attacks, redefined "imminence" to mean the absence of dispositive proof refuting the existence of an unconventional weapons program that could be used in an attack. But when U.S. troops invaded, they learned that Saddam did not possess what Bush aide Condoleezza Rice famously termed a smoking gun that could come in the form of a mushroom cloud.

The undated Justice Department white paper, a summary of a number of still-classified legal analyses, redefines imminence once again. Al-Qaida leaders are "continually planning attacks," the undated white paper says, and so a preemptive attack "does not require the United States to have clear evidence that a specific attack on U.S. persons and interests in the immediate future." Referencing the intelligence failures preceding 9/11, the paper concedes the U.S. "is likely to have only a limited window of opportunity within which to defend Americans." For an adversary attack to be "imminent," and a preemptive U.S. response justified, U.S. officials need only "incorporate considerations of the relevant window of opportunity, the possibility of reducing collateral damage to civilians, and the likelihood of heading off future disastrous attacks to America."

There's a subtlety at work in the Justice Department framework. It takes imminence out of the context of something an enemy does, and places it into the context of a policymaker's epistemic limitations. "The U.S. government may not be aware of all al-Qaida plots as they are developing and thus cannot be confident that none is about to occur," the white paper warns.

If there is a reasonable debate over what imminence means in an era of terrorism, and what standards ought to be accepted for defining it as an international norm, that framework preempts it. All that matters to justify a drone strike attack is for the U.S. to recognize it can't be all-knowing. It's the logical equivalent of the CIA's signature strike, which target anonymous military-age males in areas where terrorists operate based on a presumption that their pattern of observed behavior is consistent with those of terrorists.

It would be one thing if Obama was talking about foreigners who enlist in al-Qaida. But he's actually talking specifically about American citizens overseas who are "senior operational leader[s] of al-Qaida or its affiliated forces" – people whom the Constitution protects against the loss of life without due process of law. (The Justice Department stops short of claiming the government can take such lethal actions at home.) U.S. citizenship "does not immunize" such a person from reprisal. Here the white paper does not define what it means to be a "senior operational leader" of al-Qaida, let alone its "affiliated forces," and instead asserts the applicability of Supreme Court precedent from World War II holding that U.S. citizens who joined the Axis can be treated as enemy belligerents. (My Wired colleague David Kravets has more on the specific legal claims Obama makes.)

To read this, you might think the U.S. faced an onslaught of treason. The data show otherwise. For the third straight year, U.S. Muslim involvement in terrorism declined, according to the Triangle Center on Terrorism and Homeland Security, to the point where it's assessed to be fewer than 10 cases in a million – none of which resulted in anyone's death. The few such cases that do exist do not in any rigorous way describe "senior operational leaders" of al-Qaida. The only American in al-Qaida's senior cadre is a Californian metalhead turned propagandist named Adam Gadahn. The administration has asserted that Anwar al-Awlaki, the American citizen who incited terrorism in YouTube clips, was a senior operational leader of al-Qaida's Yemen branch, but refuses to provide evidence for the claim. Not only did the U.S. kill Awlaki in a drone strike, it later killed his 16-year old son Abdulrahman, whom it has never publicly claimed was a senior operational leader of al-Qaida.

Under the Obama administration, the decision to target members of al-Qaida abroad, both foreign citizens and Americans, is made under a regularized institutional process known by the shorthand of the "disposition matrix." One of its architects, White House counterterrorism chief, John Brennan, will testify on Thursday ahead of a Senate vote to confirm him as CIA director. Eleven senators, Democrat and Republican, wrote to the White House on Monday requesting the full secret memos – plural – explaining the administration's arguments for targeting Americans in drone strikes and commando raids.

Whether or not they receive the memos, the white paper asserts an understanding of battlefield imminence that means little more than the mere existence of al-Qaida, and unconstrained by protections for U.S. citizens that the Constitution traditionally grants. Once the U.S. makes that claim, so can others, creating pretext for further acts of war.

"The Justice Department's legal arguments purportedly defending targeted killing fundamentally misconceive the nature of self-defense," University of Notre Dame professor Mary Ellen O'Connell said in a prepared statement. "It is a right to use military force against a state that has or is about to launched a major military attack on the United States. The 9/11 attacks led to a war of self-defense in Afghanistan. That had all the hallmarks of legality. Contrast that use of force with the CIA firing of missiles from drones at a single individual and innocent bystanders in Yemen. You do not need to be an expert in international law to understand the enormous violation of law involved and the egregious conduct involved in attempting to exploit lack of knowledge of the law to achieve political cover for targeted killing."