Harry Dunn’s family is unlikely to be able to force the American woman who allegedly killed him in a motoring accident to return to Britain, a senior legal expert has warned.

Charlotte Charles and Tim Dunn, the teenager’s parents, travelled to the US yesterday after Foreign Office officials said that Anne Sacoolas no longer qualified for diplomatic immunity.

Ms Sacoolas, the wife of a US intelligence officer, is understood to have agreed to meet the 19-year-old’s parents in the United States after she claimed diplomatic immunity and left Britain.

Legal specialists say that diplomatic immunity can expire in relation to relatives of diplomats once they return to their home countries, even though it still applies to their past actions when abroad.

Dominic Raab, the foreign secretary, appeared to send a confused message in a letter to the boy’s parents. Mr Raab, who is a lawyer, wrote that it was the government’s position “that immunity . . . is no longer relevant in Mrs Sacoolas’ case, because she has returned home. The US have now informed us that they too consider that immunity is no longer pertinent.”

Mr Raab said that the case was “now a matter for [the Northamptonshire] police and the CPS to take forward”, implying that an extradition application could be made to the US.

However, extraditing Ms Sacoolas from the US would be difficult, according to Ben Keith, a barrister at Five St Andrew’s Hill chambers in London.

It has been suggested that police in Northamptonshire have only requested to interview the diplomat’s wife.

For the British government to apply for Ms Sacoolas’s extradition, police and prosecutors would have to give an undertaking to the US authorities that a criminal charge was imminent.

British detectives could invoke mutual legal assistance arrangements with their US counterparts to ask to interview Ms Sacoolas over a video link. “But she could refuse,” Mr Keith said, “on the ground that she had diplomatic immunity at the time of the alleged offence.”

He said that it would be unlikely that the police and the Crown Prosecution Service would bring a charge of death by dangerous driving without first interviewing Ms Sacoolas.

There was a possibility that they could charge her with the less serious offence of death by careless driving. Hundreds of people are convicted annually of careless driving and the evidence bar is much lower than that for dangerous driving.

Nonetheless, the Americans are historically reluctant to lift diplomatic immunity and to extradite their citizens.

“US officials take the view that if they lifted diplomatic immunity and extradited for what is a very sad accident but what they would still see as a relatively minor criminal offence, then their spies in far more hostile and difficult jurisdictions would not be able to do their jobs,” Mr Keith said.

He said that US officials would be more likely to consider lifting immunity and assessing an extradition application for crimes such a murder or manslaughter.

“Ultimately, this remains a political rather than legal question,” Mr Keith said.

This article was originally published by the Times on 14 October 2019 and can be viewed here.

Ben Keith is a barrister specialising in Extradition, Immigration, Serious Fraud, Human Rights and Public law. He has extensive experience of appellate proceedings before the Administrative and Divisional Courts, as well as applications and appeals to the European Court of Human Rights (ECHR) and United Nations. He has significant expertise in the challenge of INTERPOL Red Notices. He is ranked in Chambers and Partners and Legal 500 in the top tiers.