http://www.nationalreview.com/corner/303523/executive-privilege-congress-andrew-c-mccarthy
As you would expect, my buddy Shannen provides an excellent outline of the law of executive privilege. I do not take issue with what he explains, because it very accurately conveys the privilege as it has evolved over time. My dispute is with the underlying assumptions about the privilege, particularly with respect to the “deliberative process” aspect of it, which, as Shannen observes, rests on less solid footing than the “presidential communications” aspect.
Just as there are two species of executive privilege, so there are two species of governance within the executive branch. The first involves the president’s constitutional duties. These are broadly laid out in Article II. They involve powers of the presidency that derive directly from the Constitution. Congress may not repeal, reduce, or subject them to regulation or “oversight” that thwarts the president’s ability to carry them out.
That is why I agree the “presidential communications” aspect of executive privilege is the stronger one — and why, for example, I argued that Congress had no power to compel Karl Rove to testify during the controversy over fired U.S. attorneys. Karl was a senior advisor to President Bush, a member of the White House staff whose position was not subject to Senate confirmation or otherwise dependent on Congress. He served at the pleasure of the president to facilitate the performance of the president’s constitutional duties. In this sense, he was an appendage of Pres. Bush, and Congress could no more compel him to testify than compel the president. The president is a peer, not a subordinate, of Congress; Congress does not have the power to demand testimony from the president or his confidants — at least not on matters that involve presidential communications in the execution of the president’s constitutional duties.