Senator Rand Paul wrote a Sunday op-ed in the New York Times arguing that all Americans deserve to see the Office of Legal Counsel memos used to justify the killing of an American citizen without charges, trial, or due process of law. President Obama wants to appoint a lawyer who helped to write those memos to the U.S. Court of Appeals for the First Circuit. Crying foul are voices as diverse as Paul, Senator Ron Wyden, the ACLU, and antiwar group Code Pink.

Under pressure, the Obama Administration has already agreed to show at least some of David Barron's legal work on drone killing to senators, but as the New York Times editorialized last week, the public ought to see these memos as well. I've gone farther, arguing that Barron enabled killing that clearly transgressed against the Fifth Amendment, cannot be trusted to safeguard our constitutional rights on the federal bench, and should be disqualified from consideration.

Paul contextualizes the damage Barron has helped to do (emphasis added):

Anwar al-Awlaki was an American citizen subject to a kill order from Mr. Obama, and was killed in 2011 ... I don’t doubt that Mr. Awlaki committed treason and deserved the most severe punishment. Under our Constitution, he should have been tried—in absentia, if necessary—and allowed a legal defense. If he had been convicted and sentenced to death, then the execution of that sentence, whether by drone or by injection, would not have been an issue. But this new legal standard does not apply merely to a despicable human being who wanted to harm the United States. The Obama administration has established a legal justification that applies to every American citizen, whether in Yemen, Germany or Canada. Defending the rights of all American citizens to a trial by jury is a core value of our Constitution.

For a different assessment of Barron's legal work, here's Benjamin Wittes writing at Lawfare:

The memos Barron wrote—at least to the extent we can judge them from summaries of them in the press and in the administration’s white paper—are not permissive with respect to targeted killing. As I explained in detail in this congressional testimony, they are actually quite narrow. One can argue about whether they are too narrow or whether they are appropriately cautious, but it’s actually difficult to imagine the administration’s having adopted a more limiting set of legal rules than it did.

In a way, this is hard to dispute. The plain text of the Fifth Amendment forbids the premeditated killing of an American far from any battlefield–but after eight years of George W. Bush, featuring the legal work of John Yoo and David Addington, and the the national-security state's behavior under Obama, including the disappointing tenure of Harold Koh, I find it "difficult to imagine" executive-branch lawyers adhering to the Constitution when it forbids some action that they've settled on. After all, we've seen the federal government violate the Constitution and the law on many occasions during the War on Terrorism. Almost no one is ever punished and there are always lawyers around to twist words in ways that empower their bosses.