Following up on my earlier post about whether the Obama Justice Department really ought to be representing John Yoo — the notorious former Office of Legal Counsel lawyer during the Bush administration — Michael Ratner, president of the Center for Constitutional Rights and a professor at Columbia Law School, pointed out to me today that the Justice Department’s defense of Yoo is fraught with not only political, but ethical complications.

That’s because fundamental to any argument on behalf of a government official being sued for things he did in government is the claim of “qualified immunity” — essentially, the official is immune if it wasn’t clear at the time that what he was doing violated established rights...