FOR MORE than a month, Americans did not know whether acting attorney general Matthew G. Whitaker had received the advice of Justice Department ethics experts on whether he should recuse himself from the Russia investigation. Now, there is an answer: He did. He just chose to ignore it.

Mr. Whitaker’s decision to oversee special counsel Robert S. Mueller III’s probe, despite the opinion of dedicated officials that he ought to avoid the appearance of a conflict of interest, comes after the acting attorney general declined to request a formal review and instead brought in his own advisers to aid in an informal process.

This slippery strategy does not seem out of character for Mr. Whitaker, who has proved himself unfit for the position the Senate has not confirmed him to hold. There is, of course, his demonstrated antagonism toward Mr. Mueller’s effort. Then there is his involvement in a scam company. And don’t forget his alarming views on judicial power. A recent report from the Wall Street Journal revealing Mr. Whitaker’s already thin résumé to be slimmer still (he incorrectly claimed he was an academic all-American while playing football in college, when he really held a lower-level honor) may be the least of his disqualifications.

Mr. Whitaker could have assuaged these concerns somewhat by submitting to a formal review of his proper role. Instead, he chose to sidestep that process in favor of unofficial conversations — and then followed the advice not of the experts but of anonymous self-selected advisers who told him what he wanted to hear. Deputy Attorney General Rod J. Rosenstein reportedly will still manage the day-to-day of the investigation. But Mr. Whitaker will have the ability to block any significant action Mr. Mueller takes. And the country has even less reason to believe that he will be anything more than President Trump’s lackey.

The nomination of William P. Barr to return to the role of attorney general was a relief to observers concerned that Mr. Trump would leave Mr. Whitaker in place for the remainder of his term — and most likely a relief also to Mr. Whitaker, now operating under decreased scrutiny. Senators will have the opportunity to explore Mr. Barr’s own skepticism of Mr. Mueller’s work, as well as his commitment to the independence of the department he seeks to lead for a second time. But in the meantime, as long as Mr. Whitaker is in place, and as long as a law protecting Mr. Mueller is not, the Russia investigation is in danger.

Read more: