CRS – Legislative Purpose and Adviser Immunity in Congressional Investigations May 24, 2019: “The Trump Administration has recently questioned the legal validity of numerous investigative demands made by House committees. These objections have been based on various grounds, but two specific arguments will be addressed in this Sidebar. First, the President and other Administration officials have contended that certain committee demands lack a valid “legislative purpose” and therefore do not fall within Congress’s investigative authority. This objection has been made not only in response to investigations seeking information relating to the President’s personal finances, including his financial records and federal tax returns, but also to challenge a subpoena issued by the House Judiciary Committee for the complete version of Special Counsel Mueller’s report along with underlying evidence and materials. Second, the President has made a more generalized claim that his advisers cannot be made to testify before Congress, even in the face of a committee subpoena. This position, based upon the executive branch’s longstanding conception of immunity for presidential advisers from compelled congressional testimony regarding their official duties, was recently put into effect by the White House in a letter announcing that the President directed former White House counsel Don McGahn not to appear at a scheduled House Judiciary Committee hearing. The letter asserted that Mr. McGahn, now a private citizen, “is absolutely immune from compelled congressional testimony with respect to matters occurring during his service as a senior adviser to the President.”

While the particulars of any given information access dispute between the executive and legislative branches are important, existing legal precedent would suggest that these types of objections to Congress’s exercise of its constitutionally based investigatory powers will likely face an uphill battle…”