Former White House Counsel Don McGahn has been embroiled in congressional conflict over Special Counsel Robert Mueller’s report almost as much as Attorney General William Barr, but Barr’s prominent position often overshadows the important role McGahn could play in the ongoing investigation into alleged obstruction of justice.

McGahn, who resigned from his position in October, had been with President Donald Trump since the campaign trail. He served as general counsel for the transition and became White House Counsel upon Trump’s inauguration.

Throughout his tenure under the Trump administration, McGahn aided in the appointment of several new judges—including Supreme Court Justices Neil Gorsuch and Brett Kavanaugh—but frequently disagreed with the president on the handling of the special counsel investigation.

McGahn sat for several interviews with Mueller’s team in his capacity as White House Counsel. The final report—which describes McGahn as “a credible witness with no motive to lie or exaggerate given the position he held in the White House”—states that Trump called McGahn multiple times to request he tell then-Deputy Attorney General Rod Rosenstein that Mueller had “conflicts that precluded him from serving as Special Counsel.”

McGahn refused, and was fully prepared to resign in order to avoid carrying out these demands. He remained at his post, however, and Trump ceased his requests.

Yet when news of the attempted interference broke months later, Trump asked McGahn put out a statement denying that he had been asked to fire the special counsel. Again, McGahn refused.

All this is recounted in detail in Mueller’s public report, but in May McGahn rebuffed a congressional subpoena for documents and testimony relating to Trump’s alleged obstruction of justice.

According to a letter McGahn’s lawyer sent to House Judiciary Committee Chairman Jerrold Nadler, the White House’s new counsel, Pat Cipollone, had instructed McGahn not produce the documents “because they implicate significant Executive Branch confidentiality interests and executive privilege.” Moreover, he wrote that McGahn “continues to owe certain duties and obligations to the President which he is not free to disregard,” despite no longer working at the White House.

Nadler argued that the president has not officially invoked executive privilege, and if he did, the White House has already waived any claim of executive privilege by voluntarily disclosing documents to McGahn and Mueller.

“To be clear, a letter from the White House in service of the President’s apparent goal of blocking or delaying testimony that the President believes would be politically damaging is not a basis for Mr. McGahn to violate his legal obligation to appear before the Committee,” Nadler wrote. “Rather, if the President wishes to block Mr. McGahn’s appearance in the face of a duly issued subpoena, the burden rests with the White House to file an action in court to attempt to do so.”

When McGahn continued to withhold the requested information and failed to appear for testimony later in May, the House Judiciary Committee subpoenaed Annie Donaldson, McGahn’s former deputy, and repeated a threat to take McGahn to court.

On Monday, this threat fell to the wayside as the House Judiciary Committee struck a deal with the Department of Justice, ensuring committee members will see at least some evidence from the Mueller report. The House decided against taking both Barr and McGahn to court over subpoena defiance, although representatives are expected to vote on an authorization to go to civil court if needed on Tuesday.

John Dean, the White House Counsel under former President Richard Nixon, testified before the Committee Monday in regards to his experience with obstruction of justice. Having held the same position as McGahn, he provided insight into whether the former counsel should speak out.

“Mr. McGahn is the most prominent fact witness regarding obstruction of justice cited in the Mueller Report,” said Dean in his statement to the Committee. “His silence is perpetuating an ongoing coverup.”

Dean encouraged McGahn to come forward and testify, arguing that as a former White House Counsel, “his duty is to protect the Office of the Presidency, sometimes against the very person in charge of it.”

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