The first, which it unleashed on Monday, is to claim that the Constitution gives close personal aides to a president “absolute immunity” from congressional subpoenas trying to compel them to come testify about their official duties — even if, like Mr. McGahn, they no longer work for the president and so forcing them to show up at the Capitol would not interfere with their ability to assist him.
Administrations of both parties have taken that position, and the Justice Department on Monday unveiled a new 15-page legal opinion from Steven A. Engel, the head of the department’s Office of Legal Counsel, asserting that “Congress may not constitutionally compel the president’s senior advisers to testify about their official duties.”
Pat A. Cipollone, the current White House counsel, sent the Judiciary Committee a letter saying that the president had directed Mr. McGahn not to appear, and invoking that rationale as justification.
Representative Jerrold Nadler, Democrat of New York and the chairman of the House Judiciary Committee, denounced Mr. Trump’s move as “the latest act of obstruction from the White House that includes its blanket refusal to cooperate with this committee.”
“It is also the latest example of this administration’s disdain for law,” Mr. Nadler added.
He noted that in 2008, another Federal District Court judge, John D. Bates, ruled that President George W. Bush’s former White House counsel, Harriet Miers, had no right to skip a hearing for which she had been subpoenaed. Judge Bates, a Bush appointee, said she had to show up — although she might still refuse to answer specific questions based on a claim of executive privilege.
The executive branch did not appeal the Miers ruling, and because no appeals court weighed in, Judge Bates’s opinion does not count as a controlling precedent for other disputes raising the same issue. That left the Obama administration, in a 2014 memo, free to take the position that Judge Bates had been wrong, and Mr. Engel echoed that logic in his new memo.