Attorney General William Barr made the decision to absolve the president of obstruction of justice before even reading the Mueller report. That jaw-dropping admission is the biggest takeaway from a dismal circus of Wednesday’s testimony before the Senate Judiciary Committee by the man who is serving as the United States’ chief law enforcement official – but is transparently acting much more like the personal attorney for President Trump.

Committee chair Lindsey Graham gave proceedings a disheartening start when he made it clear in his opening remarks that the Republican focus of the day would dovetail entirely with the White House line on the issue: that the real victim here was Donald Trump, and that the FBI should be investigated for investigating the president.

Hilariously, later on this line would come back to bite the Republicans when Ted Cruz – because it’s always Ted Cruz – asked Barr first if it was unusual for the FBI to investigate a presidential candidate, and then if “the Obama FBI” had investigated any other presidential candidates. “No,” Barr categorically said, before realising his mistake. “Well,” he added, “they were investigating Hillary Clinton.” Whoops.

As is the tendency with Congressional hearings, the format – seven minutes for a Republican to ask a question, then seven minutes for a Democrat – meant the testimony felt like watching ideological tennis.

Almost all the Republicans used their time to peddle White House talking-points, trying to bring the subject round, preposterously, to their eternal bugbear: Hillary Clinton. (Reporters joked that this was a relief, as when a Republican took their turn to speak it meant nothing interesting was going to get asked, making it a good time for a toilet or cigarette break.) “Looks like my colleagues across the aisle are going for the ‘Lock Her Up’ defence,” Democratic senator Dick Durbin said at one point.

The Democrats, on the other hand, were surprisingly effective at eviscerating whatever remained of Barr’s credibility as an unbiased law enforcement official. Several of them – including presidential candidates Amy Klobuchar and Kamala Harris – are former prosecutors, and they used their cross-examination skills well. Harris especially stumped Barr on the question of whether it was appropriate to include Rod Rosenstein – a key witness in the obstruction of justice segment of the Mueller report – in the decision not to prosecute.

Barr, for most of the hearing, feigned a bumbling, “I’m sorry could you repeat the question” approach to help him run down the clock and avoid questions he didn’t want to answer. But on occasion, his contempt for legislative oversight shone through. Late in the hearing, asked about a phone call he had with Mueller after the Special Counsel took the unprecedented step of writing him a letter objecting to how he had presented the investigation’s findings, Barr said he would not provide the committee with the notes of their subsequent phone call. Asked why not by Senator Blumenthal, Barr testily said, “why would I?”

Barr, who misled the nation about the contents of the report both in his original letter to Congress and in his press conference spinning the report the morning of its release, spent the hearing continuing to gaslight the country – not just lying but obfuscating to such a degree that one can only imagine he hopes some listeners will begin to question their own recollection of Mueller’s report.

Again and again, when asked for details, Barr demurred in sneaky ways that muddied the waters. Asked if Mueller had objected to any redactions Barr made to the version of the report that was released to the public, Barr replied: “I wouldn’t say objected.” Barr said that “If Mueller had found evidence of obstruction of justice, he would have said that”, even though Mueller's report made clear that he did not believe he had the authority to make this determination and that he had uncovered several instances that could be construed as obstruction of justice.

He kept repeating that the president “fully cooperated” with the investigation, even though Trump consistently declined to testify in person. He kept saying that only “the full report” mattered, despite having called a press conference before its release to spin its narrative. He appealed with faux-outrage that “we have got to stop using the Department of Justice as a political weapon,” while encouraging Republicans calling for investigations into Clinton.

He kept claiming that there was “no underlying crime” which is misleading on two counts: one, because as Mueller wrote in the report that the absence of an underlying crime is no bar to committing the crime of obstruction of justice, and two, because there were plenty of underlying crimes uncovered but spun off from the investigation, including election fraud. He also maintained that the president is able to stop an investigation into him if he believes it to be “unfair” – another misstatement of the law, as CNN’s Asher Rangappa, a former FBI agent, pointed out.

Democrat Maisie Hirono castigated Barr for his behaviour, comparing him to Kellyanne Conway as someone who has allowed their credibility to be destroyed in the service of Trump. “You used every advantage of your office to make it look like the president was cleared ... you put the Justice Department behind a public relations effort on behalf of the president,” she said.

“Do you think it’s ok for the president to ask his White House counsel to lie?” Hirono asked. No answer. “Do you think it’s ok for the president to threaten or offer a pardon?” As Barr squirmed, Lindsey Graham intervened. “You have slandered this man,” Graham said, with yet more faux-outrage.

Kamala Harris was probably the most prepared for Barr’s approach. “Has the president or anyone at the White House asked or suggested you open an investigation?” she asked, probing as to whether Trump had asked the attorney general to investigate anyone. Barr looked shifty. “I wouldn’t say suggested,” he offered. “Hinted?” Harris asked sarcastically. “Inferred?” Barr had no answer for this that wouldn’t get him into trouble. “I don’t know,” he said finally.

Gaslighting is a modern, Trumpian tactic. It felt odd coming from Barr, a man who looks like an old-school, straight-talkin’ small-town lawyer. But perhaps it is less surprising considering Barr’s history of helping to cover up the Iran-Contra scandal when he was attorney general for George HW Bush. Maybe, while everyone is so concerned about Barr “torching” his reputation, as the Washington Post editorial board put it, it was that very reputation that made him the perfect candidate for Trump in the first place.