Dominic Raab, Britain’s deputy prime minister, resigned on Friday after an investigation into claims that he had bullied subordinates, as Prime Minister Rishi Sunak’s struggles to put a legacy of scandal behind his Conservative government.
Mr. Raab, a hard-line Brexiteer who is one of Mr. Sunak’s most loyal political allies, had long denied allegations of abusive behavior. But the investigation, by an independent barrister, laid out a litany of cases in which civil servants accused Mr. Raab, who also serves as justice secretary, of mistreating them.
Mr. Raab becomes the third cabinet minister in six months to be forced out over ethics issues, illustrating again the challenge that Mr. Sunak has had in delivering his promise to lead a government of “integrity, professionalism and accountability at every level.”
Mr. Sunak rose to power after his former boss, Boris Johnson, was caught in a whirlpool of scandals, most prominently a series of Downing Street parties that violated lockdown rules. His immediate predecessor, Liz Truss, was forced out after her trickle-down tax cuts backfired.
While Mr. Sunak has calmed the waters on economic policy, he has found it harder to dispel the whiff of scandal. In his letter of resignation sent to the prime minister, Mr. Raab made it clear that he was leaving his position with some reluctance, arguing that the inquiry “dismissed all but two of the claims” against him and that the adverse findings against him were flawed.
“In setting the threshold for bullying so low, this inquiry has set a dangerous precedent,” he wrote. “It will encourage spurious complaints against ministers and have a chilling effect on those driving change on behalf of your government — and ultimately the British people.”
The uproar over Mr. Raab came just as Mr. Sunak had finally gained some political momentum, signing deals with the European Union on Northern Ireland and with France on migration issues. The perception that Mr. Sunak was a responsible leader whittled down the wide lead in polls held by the opposition Labour Party over the Conservatives, though Labour remains ahead by double digits.
Mr. Raab is one of a cadre of young politicians who rose to power in the bitter debate over whether Britain should leave the European Union. He was co-author of a book, “Britannia Unchained,” which described a vision of post-Brexit Britain as an agile, low tax, lightly regulated business mecca — often nicknamed Singapore-on-Thames.
Promoted to the cabinet when Theresa May was prime minister, Mr. Raab resigned his job as Brexit secretary in November 2018 in protest of her proposals for extracting Britain from the European Union.
After an unsuccessful run for Conservative Party leader in 2019, Mr. Raab supported Mr. Johnson and was rewarded with the post of foreign secretary. He had a moment in the spotlight when Mr. Johnson became seriously ill with Covid and deputized Mr. Raab, as the ranking minister, to preside at cabinet meetings while Mr. Johnson was in the hospital.
Later, Mr. Raab was harshly criticized for staying on vacation on a Greek island during the chaotic withdrawal of British and American troops from Afghanistan.
When Mr. Johnson was forced out as prime minister last July, Mr. Raab backed Mr. Sunak over Ms. Truss in the party leadership contest. After Ms. Truss defeated Mr. Sunak, she stocked her cabinet with loyalists and cast Mr. Raab into the political wilderness.
His fortunes rebounded weeks later when Ms. Truss was forced to resign, and Mr. Sunak finally captured 10 Downing Street, with Mr. Raab’s backing. He rewarded Mr. Raab, who was once a lawyer, with the post of justice minister and added the title of deputy prime minister, an unpaid, largely honorary position that does not come with an automatic right to succeed to prime minister.
But even before he was brought back into government, newspapers had reported claims about Mr. Raab’s behavior toward officials, raising questions about whether Mr. Sunak should have been aware of the allegations against him at the time of his appointment.
And soon after resuming his place in the cabinet, Mr. Raab was under fire because of reports that he bullied colleagues. Simon McDonald, a diplomat who ran the Foreign Office while Mr. Raab was foreign secretary, said he had been “abrasive and controlling,” making junior staff members scared of entering his office.
“It was language, it was tone,” Mr. McDonald told Times Radio in November. “He would be very curt with people. And he did this in front of a lot of other people. I think people felt demeaned.” Mr. McDonald said that he had raised concerns with Mr. Raab about his treatment of subordinates.