To be clear, no one would expect the Obama Administration to arrest this man were he engaged in a firefight with U.S. forces in Iraq, Afghanistan, or that Pakistani compound where Osama bin Laden was hiding. The problem with the Obama Administration is that it proposes to extend the logic of the battlefield to the entire globe for a war of indefinite length against a difficult to identify enemy.

That is why civil libertarians are objecting. As the ACLU puts it:

Outside armed conflict zones, the use of lethal force by the United States is strictly limited by international law and, at least in some circumstances, the Constitution. These laws permit lethal force to be used only as a last resort, and only to prevent imminent attacks that are likely to cause death or serious physical injury. Such a program of long-premeditated and bureaucratized killing is plainly not limited to targeting genuinely imminent threats. Any such program is far more sweeping than the law allows and raises grave constitutional and human rights concerns.

As of last year, there were three American citizens in addition to al-Awlaki on the Obama Administration's assassination list. Who are they? What is the evidence against them? Have they already been killed? Have any other names been added to the list? Have a hundred other names been added? It's impossible to know for sure, because the president insists he has no obligation to answer these questions. He claims not just the power to kill, but to do so in secret on no authority but his own.

In the criminal justice system, the government is required to be transparent about its facts, all evidence is shared with the defense, the accused is guaranteed the right to counsel, an impartial jury is selected, and the standard for a conviction is "beyond a reasonable doubt." Despite these safeguards, the Innocence Project estimates that between 2.3 percent and 5 percent of all American prisoners are innocent. During the Bush Administration, Dick Cheney assured us that the folks held at Gitmo were "the worst of the worst." As it turned out, however, a lot of them were actually innocent.

Even if no U.S. president ever intentionally abused the power to order the secret assassination of his fellow citizens -- and is any power more corrupting than the ability to kill whomever you like in secret? -- it is folly to imagine that innocents won't be assassinated under this policy, if only accidentally, should it go on for very long. That is what happens when checks and balances are abandoned, oversight is eschewed, and citizens are stripped of their rights without due process. And if this power was abused? It is difficult to imagine a more horrific scenario than the constitutional crisis that would result from a president murdering while asserting impunity.