The Department of Justice issued a memorandum to President Donald Trump’s legal counsel Monday stating that “Congress may not constitutionally compel the President’s senior advisors to testify about their official duties.”

The House Judiciary Committee subpoenaed Trump’s former White House Counsel Don McGahn last week to testify specifically about matters regarding Special Counsel Robert Muller’s report.The memorandum was in direct response to current Trump counsel Pat Cipollone’s question as to whether McGahn is legally required to appear before the committee to testify.

The DOJ’s eight page memorandum, written by Assistant Attorney General Steve Engel, clearly argues the separation of powers and states that “Congress could not lawfully exercise any inherent contempt authority against Mr. McGahn for asserting immunity. The constitutional separation of powers bars Congress from exercising its inherent contempt power in the face of a presidential assertion of executive privilege.”

Last week, Judiciary Committee chairman Rep. Jerrold Nadler, D-NY, threatened he was prepared to have his panel vote to hold McGahn in contempt of Congress if did not appear before the committee on Tuesday. It would be a contempt citation and could result in the House turning to a federal court to try to enforce its subpoena but the memorandum makes clear that there is a separation of powers issue that must be considered.

“We provide the same answer that the Department of Justice has repeatedly provided for nearly five decades: Congress may not constitutionally compel the President’s senior advisors to testify about their official duties.”

“This testimonial immunity is rooted int he constitutional separation of powers and derives from the President’s independence from Congress,” the memoradum states.

The memo referred to former Attorney General Janet Reno, who worked under President Bill Clinton. She stated that “subjecting a senior presidential advisor to the congressional subpoena power would be akin to requiring the President himself to appear before Congress on matters relating to the performance of his constitutionally assigned executive function.”

Questions and Answers Regarding “Testimonial Immunity before Congress of the Former Counsel to the President” As Per Department of Justice.

Question: Can Congress compel former Counsel to the President, Don McGahn II, to testify about matters described in the Mueller report?

Conclusion: No. “The immunity of the President’s immediate advisers from compelled congressional testimony on matters related to their official responsibilities has long been recognized and arises from the fundamental workings of the separation of powers. Those principles apply to the former White House Counsel. Accordingly, Mr. McGahn is not legally required to appear and testify about matters related to his official duties as Counsel to the President.”

This OLC opinion is based on nearly 50 years of bi-partisan precedent:

Administrations from both parties have regularly reaffirmed the opinion of then-Assistant Attorney General William Rehnquist in the 1971 Rehnquist Memorandum describing the legal basis for protection from forced testimony.

In 2014, during the Obama Administration, the Office of Legal Counsel (OLC) concluded that Mr. David Simas, as Assistant to the President and Director of the Office of Political Strategy and Outreach, was “immune from compulsion to testify before the [c]ommittee,” and he declined to testify.

Since the 1970s, OLC has consistently advised that the President and close advisers are protected from being forced to testify before Congress.

The Executive Branch’s position on testimonial immunity reflects historical practices dating back nearly to the 1939 establishment of the Executive Office of the President.

Both Republican and Democrat Administrations invoked this protection:

2014 – President Barack Obama directed Assistant to the President and Director of the Office of Political Strategy Outreach David Simas not to appear in response to a Congressional subpoena.

2007 – President George Bush directed former Counsel to the President Harriet Miers not to appear in response to a Congressional subpoena.

1999 – President William Clinton directed Counsel to the President Beth Nolan not to appear in response to a Congressional subpoena.

Constitutionally-enshrined separations of powers prohibit Congress from forcing the President and his advisors to testify:

As the head of a co-equal branch of government, the President is protected from Congressional subpoenas to appear and testify. As an extension of the president, his advisers are afforded the same rights.

In order to perform his duties, the President has strong interest in confidentiality and candor from close advisers. Forcing these advisers to appear before Congress threatens these characteristics central to effective operation of the Executive Branch.

Without protection from forced testimony, Congress could cripple the Executive Branch by forcing advisers to dedicate all their official time to preparing for testimony with multiple subpoenas.

Protection from forced testimony applies to former advisers:

The Executive Branch’s long-standing position on compelled congressional testimony of senior presidential advisers is consistent with related Supreme Court precedent.

If protection from forced testimony expired at the end of official tenure, then confidentiality and candor of advisors would still be at risk.

Bottom Line: The President’s immediate advisers are an extension of the President. Congress may no more summon the President to a congressional committee room than the President may command Members of Congress to appear at the White House.