You might have heard about a Congressional subpoena threat. One of the commenters on my earlier post apparently has read at least this, if not necessarily the Congressional Research Service study upon which it was based. Yes, Clinton White House aides testified on 47 different occasions in front of Congressional committees; the vast majority of the occasions had to do with the Whitewater investigation. The CRS report says nothing about how many of the appearances were actually in response to subpoenas, though I have no doubt that the Republicans then controlling Congress threatened subpoenas. (If anyone has numbers here, I’d love to see them.)

But this passage from the CRS report is worth pondering:

The range of executive branch officials who may appropriately assert executive privilege before congressional committees, and the circumstances under which they may do so, remains unresolved by the courts, and is a matter that may be determined by case-by-case accommodation between the political branches. Some guidance in this regard was offered by Chief Justice William Rehnquist, when he was Assistant Attorney General in the Nixon Administration. Rehnquist distinguished between “those few executive branch witnesses whose sole responsibility is that of advising the President,” who “should not be required to appear [before Congress] at all, since all of their official responsibilities would be subject to a claim of privilege,” and “the executive branch witness ... whose responsibilities include the administration of departments or agencies established by Congress, and from whom Congress may quite properly require extensive testimony,” subject to “appropriate” claims of privilege.

Following a review of Rehnquist’s statement, precedents and practice
concerning congressional access to executive branch information (particularly, the testimony of presidential advisers), and constitutional issues, it is possible to
suggest some key legal factors that together may determine whether a congressional request for the testimony of one who advises the President will be honored. (1) In the view of the executive, the few individuals whose sole duty is to advise the President should never be required to testify because all of their duties are protected by executive privilege. (2) The executive has conceded that an official who has operational functions in a department or agency established by law may be required
to testify, although at times such an official may invoke executive privilege. (3)
Congress may increase its leverage if the position of the potential witness is subject
to Senate confirmation.

If this is correct, everyone in the DoJ is more or less fair game, but the issue remains with respect to folks in the White House. The presumption seems to weigh in favor of claims of privilege here, but the matter is much more likely to be resolved in the court of public opinion than in any other court:

When faced with a refusal by the executive branch to comply with a demand for information, Congress has several alternatives to inherent and statutory contempt, although these alternatives are not without their own limitations. One approach is to seek declaratory or other relief in the courts. Previous attempts to seek judicial
resolution of inter-branch conflicts over information access issues have encountered
procedural obstacles and have demonstrated the reluctance of the courts to resolve
sensitive separation of powers issues. Other approaches may include, inter alia,
appropriations riders, impeachment, and a delay in the confirmation of presidential
appointees.

If you care to read more, here’s an article ("Congressional Access to Information: Using Legislative Will and Leverage") by Louis Fisher, one of the deans of separation of powers studies.

Update: As the commenter John below notes, roughly half the Clinton Administration appearances were before a Democratic Congress; the other half, by my count, took place after the Republicans gained control of Congress. Here’s Byron York in an article summarizing the CRS report:

Republicans argue that the U.S. attorney issue is different from Whitewater, in which by 1994 the Clinton administration had sought the appointment of an independent counsel to conduct a criminal investigation. In the U.S. attorney controversy, says Michael Carvin, who served in several top jobs in the Reagan Justice Department, “All they are complaining about is what everybody concedes is a prerogative of the president to make decisions about at-will employees. Since there is no allegation that the president has done anything in the sense of exercising a power he doesn’t have, they are going on a fishing exhibition.”

“The only conceivable reason I could think for making them testify under oath is to set a perjury trap,” adds Noel Francisco, who in recent years served in the Bush White House counsel’s office as well as the Justice Department. “They are not challenging the legality of anything the president has done; they are just snooping around. I can’t imagine why they want to get people under oath other than to play this game of gotcha.”

Of course, Democrats have different views. Constitutionally, the Republicans are, I think, on stronger ground: privilege surely gives way before a criminal investigation, but not necessarily in a merely "political" dispute. Whether the Republicans have a comparably strong political ground remains to be seen.