In 1989, Barr, then assistant attorney general in charge of the Justice Department’s Office of Legal Counsel, determined that the F.B.I could legally seize criminal suspects in foreign countries without consent from their governments. In doing so, Barr changed the department’s position — in a 1980 legal opinion, the government said that such kidnappings were unlawful.

It was a controversial opinion, especially given its key implication at the time — that the United States could abduct Gen. Manuel Noriega of Panama, who had seized power that spring. In response, Congress called Barr to testify. “Kidnapping a suspect would make the U.S. into an international outlaw,” Representative Don Edwards of California said during the hearing, as he outlined the consequences for America’s reputation if federal authorities had free rein to kidnap. Congress also asked Barr to release his memorandum to the public, but he refused. Instead, he wrote a 13-page summary that he claimed contained its “principal” arguments and conclusions, something that should sound familiar to contemporary observers.

Except it didn’t. In 1991, Congress obtained a copy of the full memo. It contained several points not present in the summary, including the contention that the president of the United States could ignore the United Nations’ prohibition of state-sponsored kidnapping.

Barr misled Congress and the public through omission. But by then he was already on his way to confirmation as attorney general under President George H.W. Bush, where he would recommend pardons for key figures in the Iran-contra scandal, which stymied a yearslong investigation into executive-branch lawbreaking that implicated the sitting president.

Helping Republican presidents act with impunity is William Barr’s stock-in-trade — it’s what he does. Even before joining Trump, he wrote an unsolicited memo arguing outright that a president cannot be charged with obstruction of justice if the underlying actions fall under his lawful authority and the accusations are false — the same argument he made at Wednesday’s hearing. “Most of the obstruction claims that are being made here, or episodes, do involve the exercise of the president’s constitutional authority,” Barr said to Senator Pat Leahy of Vermont. And he asserted, “We now know that he was being falsely accused.”

For Barr, there are no apparent limits to presidential authority, at least as long as that president is a Republican. His theory of presidential immunity did not extend to Bill Clinton, for example, whose impeachment Barr defended.

The memo even shows the same lack of interest in the facts of the investigation that Barr demonstrated during his exchange with Senator Kamala Harris of California, during which he admitted that neither he nor his office examined the evidence behind the Mueller report before determining the president could not be charged with obstruction of justice.