UPDATE: On Feb. 14, 2019, the Senate confirmed William Barr to be the next attorney general of the United States by a vote of 54-45.

Last month, news broke that in June 2018, President Trump’s current nominee for attorney general, William P. Barr, sent an unsolicited 20-page memo to the Justice Department critiquing special counsel Robert Mueller’s current investigation into Russian election interference.

Barr, who previously served as attorney general under President George H.W. Bush, penned the memo as “a former official deeply concerned with the institutions of the Presidency and the Department of Justice.” The memo questions the scope of Mueller’s investigation, and it argues that Mueller should not be permitted to demand answers from the president about possible obstruction of justice based on attempts by Trump to pressure former FBI Director James Comey to drop his investigation of Trump’s ex-National Security Advisor Michael Flynn.

The fact that Barr sent Trump this memo, and may have subsequently been rewarded with a nomination to join Trump’s cabinet, raises serious concerns. To start, the memo’s legal theories advance an overly expansive view of presidential power. More specifically, the memo prompts questions about whether Barr would order Mueller to halt further inquiry into possible obstruction by the president if the Senate confirms him. It even raises questions about whether Barr deliberately sought to curry favor with Trump by taking a position favorable to him in order to secure a top government position.

Legal commentators are divided in their interpretation of the Barr memo. Marty Lederman, a former top Obama administration lawyer, attacks the memo for “conjuring from whole cloth a preposterously long set of assumptions” about Mueller’s investigation. He also critiques Barr’s analysis, more broadly, for its sweeping views of the president’s constitutional role and prerogatives, including the notion that the president has “absolute” and “all-encompassing” constitutional authority over actions by executive branch officers in carrying out law enforcement powers given to them by Congress, including decisions about criminal investigation and prosecution. In a New York Times op-ed, Daniel Hemel and Eric Posner go further, arguing that Barr’s memo “seriously damages his credibility and raises questions about his fitness for the Justice Department’s top position.”

Others, however, have been more muted in their critiques. For example, Jack Goldsmith, who served as head of the Justice Department’s Office of Legal Counsel under George W. Bush, offers a qualified defense of Barr’s memo, maintaining that Barr’s positions on executive power have “significant support” in precedent. While that view may not be surprising coming from a former top lawyer in the George W. Bush administration, perhaps Goldsmith’s more interesting point is that a close reading of the Barr memo suggests that Barr has not already made up his mind to stop Mueller’s investigation into obstruction by Trump. Rather, Goldsmith suggests, the memo may actually and openly concede a plausible path to Trump’s eventual guilt. Goldsmith points to Barr’s statement that he is “in the dark about many facts” and Barr’s recognition that, at least in some circumstances, the president can commit obstruction of justice by sabotaging a proceeding’s truth-seeking function — for example, by encouraging perjury or inducing a witness to change his or her testimony.

That is a critical concession, according to Goldsmith, and it reduces the importance of what has been the most attention-grabbing argument in the Barr memo — that Mueller could not pursue an obstruction charge if Trump merely “hoped” Comey would drop his investigation of Flynn or fired Comey without proof that Trump sought to impair evidence-gathering.

Even if Goldsmith is right that Barr has not entirely prejudged Mueller’s investigation, however, the memo is worrying and should trigger intensive scrutiny by the Senate during the upcoming confirmation hearings.

The Senate needs to press Barr on his views of executive power, which will have ramifications far beyond the Mueller investigation. The Senate should not confirm any attorney general whose extreme views of presidential power diverge from Supreme Court precedent and a proper regard for our constitutional separation of powers. My colleagues have already described how Barr previously laid the groundwork for massive violations of Americans’ privacy rights in creating the National Security Agency’s bulk data collection program. The Barr memo enhances our fears about how its author might further erode constitutional rights if he is again appointed attorney general.

The Senate needs to probe Barr on his views of obstruction of justice and how he might interpret the federal obstruction law if he knew more about the facts. In particular, the public needs to know under what circumstances Barr would halt Mueller’s obstruction investigation. Even if Barr was acting as a well-intentioned former public servant, and not as a suppliant for a client, it is essential to scrutinize how his positions on the presidency could affect the ongoing investigation into possible malfeasance by this particular president. And the Senate must likewise demand answers from Barr on whether, and to what extent, he will use claims of executive privilege to keep secret portions of Mueller’s report, stymying further investigation by Congress.

Senators should ensure that the nation’s top law enforcement official isn’t going to stand in the way of a full and accurate account of key events in the Trump presidency.

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