Barr’s Defense of Trump Rewards the President With the Attorney General He Wanted

“There was relentless speculation in the news media about the president’s personal culpability,” Mr. Barr told reporters on Thursday. “Yet, as he said from the beginning, there was in fact no collusion.”

When Mr. Trump nominated Mr. Barr as attorney general in December, some viewed his age, 68, and establishment pedigree as signs that he would act independently in his handling of the Russia investigation.

Having already served once as attorney general, they said, Mr. Barr would be more concerned with protecting his own reputation than the president’s.

But based on his views of executive power and his conservative social and political ideology, it was not entirely a surprise that Mr. Barr would side with Mr. Trump against those who argued that he broke the law in his efforts to undermine Mr. Mueller’s investigation of his campaign’s ties to Russia.

He had made those views clear last June in a 19-page memo he wrote as a private citizen for the Justice Department, in which he castigated Mr. Mueller’s investigation for “proposing an unprecedented expansion of obstruction laws” that he said could have “grave consequences” for the presidency.

That memo, which critics have characterized as a kind of audition tape to serve as a replacement for his ousted predecessor, Mr. Sessions, turned out to be an accurate road map to Mr. Barr’s handling of the Mueller report. He acknowledged on Thursday that he disagreed with Mr. Mueller on several legal theories on potential obstruction.

Mr. Barr’s untrammeled view of executive power goes back to the Bush administration, when he counseled Mr. Bush that he had the right to start a major war in the Persian Gulf without the authorization of Congress. Mr. Bush, more cautious than his deputy attorney general at the time, asked Congress for a vote to support the war.

“Bill Barr is arguably going back to his worst instincts,” said Laurence H. Tribe, a professor at Harvard Law School and an outspoken critic of Mr. Trump. “He is bending over backward to serve as an advocate for the president and the presidency.”