Zero. If you’re keeping score, that would be the number of American citizens assassinated so far by President Obama. Oddly enough, it turns out to be the same number of our countrymen killed by President Bush. It was during the latter’s administration that, according to National Review’s Kevin D. Williamson, we conservatives began falling into “dangerous error” in the indulgence of executive power. In Mr. Williamson’s telling, this wayward path has led to our “mute consent” in — and outright “cheering” of — President Obama’s reported authorization of the assassination of Anwar al-Awlaki, an American citizen and al-Qaeda terrorist.

But wait a second, it’s not just an authorization. In “Assassin-in-Chief” (Nov. 1, 2010), as well as in several similar treatments of this topic on NRO’s blog, the Corner, Mr. Williamson informs us that the president even has an assassination “plan” — and not just for Awlaki. Picking up steam, he further inflates the wartime authorization of the killing of a single jihadist — one tied to multiple terrorist plots, including the 9/11 attacks — into an assassination list. By the time he’s done, there’s no telling how many of us the capo di tutti capi–in–chief is fixing to rub out.

To be clear, I’m a Kevin Williamson fan. That is why I am perplexed by his hyperbole, a sort of “Conservatives Gone Wild” in which I am cast in the starring role. At Exchequer, the NRO blog where he consistently delivers stellar analysis of the nation’s woebegone fisc, Mr. Williamson is admirably quick to point out that he is an English major, not an economist. Would that such pangs of humility caused him to think twice before trying his hand at constitutional law. 

To begin with, the entire premise of his essay — the contention that the ongoing war has produced “a disturbing expansion of executive power” — is wrong. There has not been any expansion. The Bush years actually ushered in unprecedented restrictions on the commander-in-chief’s discretion to deal as he sees fit with enemy combatants — including Americans. 

In June 1942, the Führer dispatched teams of saboteurs to conduct a terrorist campaign on U.S. soil. One was a 22-year-old American citizen named Herbert Hans Haupt. The Nazi infiltrators were arrested by the FBI, but Pres. Franklin D. Roosevelt directed that they be detained as enemy combatants, tried by military commission, and put to death — i.e., the executive branch acted as judge, jury, and executioner. Haupt duly met his demise, along with five others, in the District of Columbia’s electric chair about seven weeks after they were captured. Because the nation was at war with the Nazis, the fact that Haupt was an American citizen made no difference — he was treated just as his confederates were. 

Mr. Williamson mentions neither Haupt nor the further inconvenience that a unanimous Supreme Court, in Ex Parte Quirin, declined to interfere in the commander-in-chief’s decision to have an American citizen killed. To the Supreme Court, decades before there was a Bush administration, it was immaterial even that Haupt had been apprehended inside the United States, far from any traditional battlefield, at a time when the civilian courts were open and functioning.

Looking at his pocket Constitution and apparently little else, Mr. Williamson divines a “sandy foundation” on which the president’s sparse and nebulous national-security authority stands — just commander-in-chief of the armed forces, “that is all.” On the other hand, the World War II–era Supreme Court, steeped in centuries of Anglo-American jurisprudence, grasped two rudimentary points that elude Mr. Williamson.

First, that same Constitution assigns exactly no national-security authority to the federal judiciary — the branch of government Mr. Williamson would put in charge of American enemy combatants. As the Court explained in the 1948 Chicago & Southern Air Lines case, “the Judiciary has neither aptitude, facilities nor responsibility” for national-security decisions. In our system, these matters are instead the province of officials “directly responsible to the people whose welfare they advance or imperil.” They are political in nature, not legal. Thus, in the 1950 Eisentrager case, the Court turned away enemy combatants seeking its intervention during post-war occupation. To grant them judicial review or civilian trials would, the justices said, “hamper the war effort and bring aid and comfort to the enemy.” “It would be difficult,” they elaborated, “to devise more effective fettering of a field commander than to allow the very enemies he is ordered to reduce to submission to call him to account in his own civil courts and divert his efforts and attention from the military offensive abroad to the legal defensive at home.”