LONDON — The family of Harry Dunn, the teenage motorcyclist who was killed in a crash in Britain in August, is suing the Trump administration for “lawless misconduct,” a spokesman for the family said on Tuesday.
Mr. Dunn, 19, died after his motorcycle collided with a car that the police said had been traveling on the wrong side of the road on Aug. 27 in Brackley, a town about 60 miles northwest of London.
The case ignited a diplomatic tug-of-war between Britain and the United States after the woman thought to be driving the car, Anne Sacoolas, the wife of an American diplomat, claimed immunity and left the country a little over two weeks after the accident.
Seeking resolution in the case, Mr. Dunn’s parents have petitioned the highest echelons of government on both sides of the Atlantic, culminating with a meeting at the White House this month that left them disillusioned after President Trump unexpectedly announced that Ms. Sacoolas was in an adjacent room and wanted to meet with them. They declined to do so.
Now the parents, Tim Dunn and Charlotte Charles, are pursuing legal action against both governments for their handling of the case, and against Ms. Sacoolas as well.
“We are bringing claims against both Mrs. Sacoolas in the U.S.A. for civil damages as well as the Trump administration for their lawless misconduct and attempt to cover that up,” Radd Seiger, a spokesman for the family, said in a statement on Tuesday.
Mr. Seiger said that the Trump administration was “not only hellbent on breaking international laws, rules and conventions on diplomatic immunity, but they have no care or concern for the welfare of Harry’s family or any real intent on finding a solution.”
He said the family had been “lured” to the White House “under a pretense only to be ambushed by the administration who tried to engineer a grotesque meeting” between the family and Ms. Sacoolas.
Speaking to reporters immediately after their meeting with Mr. Trump, Mr. Dunn and Ms. Charles said the president had seemed “sincere” when he said that he would “push to look at this from a different angle,” but Mr. Seiger said on Tuesday that they now have “no faith in his words.”
The Trump administration, Mr. Seiger said, had “tried to twist and contort the laws on diplomatic immunity to argue that Mrs. Sacoolas should be permitted to skip the U.K. after her actions and escape justice.”
The family hopes to take the case to United States federal court, he said. Last week the Dunns announced that they were pursuing legal action against the British government.
They said they would ask London’s High Court to review a decision by the British Foreign Office “to advise Northamptonshire Police that Mrs. Sacoolas has diplomatic immunity and to have that decision quashed,” Mr. Seiger said in a text message on Sunday.
Neither the Foreign Office nor the White House could immediately be reached for comment on Tuesday.
Dominic Raab, the foreign secretary, told Parliament last week that Ms. Sacoolas, whose husband worked at a Royal Air Force base that hosts a United States Air Force communication station, was entitled to immunity under a 1995 treaty between Britain and the United States. British and American officials had said earlier that Ms. Sacoolas’s claim of immunity was no longer relevant because she had returned home.
Mr. Raab told Parliament that the day after the crash the United States Embassy in London informed the Foreign Office that the wife of an Air Force base employee had been involved in a traffic accident. Britain made a formal request to the United States Embassy on Sept. 5 to waive the immunity protection, but it was declined.
Ms. Sacoolas left Britain on Sept. 15. Mr. Raab said that the Foreign Office was told of her departure the next day.
Ms. Sacoolas cooperated with the local police immediately after the crash, but the next day she informed them of her diplomatic immunity, effectively halting communication with her, Chief Constable Nick Adderley of the Northamptonshire Police told reporters last week.
But that could change.
Mr. Adderley said last Tuesday that Ms. Sacoolas had agreed to be interviewed by British officers in the United States, and that the evidence file his officers submitted to the Crown Prosecution Service was incomplete without her account of the crash.