Jovianne Waltrick was just 16 years old in 1997, when she was killed in a five-car pile-up in Washington DC caused by a drunk-driving Georgian diplomat named Gueorgui Makharadze.

A US court sentenced Makharadze to seven years in prison after Georgia waived his right to diplomatic immunity, the legal exemption granted to officials working abroad by their host state.

Twenty-two years later, an American woman has found herself in an eerily similar position, suspected of involvement in the death of 19-year-old Harry Dunn in a road accident in August. As the wife of an American diplomat, Anne Sacoolas was granted diplomatic immunity and left the UK.

Unlike Georgia, however, the US has refused to waive diplomatic immunity for Sacoolas, sparking outrage from the British public and anger from Harry Dunn’s family.

The teenager’s father Tim Dunn said: “We can’t let our son die and then nothing be answered for.”

The row has reached the top levels of government in both countries, with both Prime Minister Boris Johnson and President Donald Trump speaking out on the issue.

On Friday, Johnson said that he had pressed Trump to lift Sacoolas’ diplomatic immunity.

“In my experience, America is very, very reluctant to allow its nationals to be tried overseas, and is absolutely ruthless in enforcing the code of diplomatic immunity,” the prime minister said.

“I must say, I don’t think it was appropriate for that provision to be used in this case.”

So is diplomatic immunity fit for purpose, or is it simply a get out of jail free card? 

Diplomatic immunity is one of the few things that is almost universally agreed upon by states around the world. Its governing treaty, the Vienna Convention on Diplomatic Relations, has 192 (of a possible 195) state signatories, far more than equivalents on climate change, chemical weapons or racial discrimination.

The reason is simple – it’s in the interests of all states to abide by a law that ensures their diplomats can work abroad without the threat of being detained, harassed or taken hostage in an international incident.

Diplomats working in friendly countries have little to fear from such threats, but a universal treaty has to be applied universally – all diplomats, no matter where in the world they are working, have the same protections.

“The key point is that you’re asking people to go themselves and take their families into difficult circumstances in many cases, and to do that you have to provide them with a level of protection that they otherwise might not require or need,” said Craig Barker, professor of international law at the London South Bank University.

“Most diplomats, in fact all diplomats apart from a few renegade diplomats, in spite of having immunity, comply with the law both in their official acts and in their private acts.”

And last December, the foreign office said a diplomat had been expelled from the UK following allegations of two rapes and one attempted rape from 2017. The diplomat’s home country rejected the UK’s request to waive the suspected perpetrator’s immunity.

In the case of Sacoolas, lawyer Chris Daw QC told HuffPost UK that diplomatic immunity had been applied correctly “in the legal sense” and that it is “an absolute right in the hands of the country which has appointed the diplomat to a foreign jurisdiction”.

“But the question isn’t really around the legal side of this,” he added. “It’s not about guilt, it’s about whether or not she will participate in the due process of an English criminal investigation.”

“All the police want to do is investigate properly, conduct an interview with this lady and send a file to the Crown Prosecution Service. And then, if there is evidence, they want to follow the due process of law. That’s all the police, the government and, as I understand it, the family are asking for.”

Ultimately, the decision lies with Trump. So far, he has been dismissive towards the UK’s concerns, saying at a press conference earlier this week that wrong-way driving is something that “happens”. Notes he carried with him during the event suggested that the official US position is that Sacoolas “will not return to the UK”.

Daw told HuffPost UK that the president’s nationalistic tendencies could factor into his decision-making process, particularly as he campaigns for re-election.

Trump may feel that “it’s more important to be seen to be standing up for an American than it is to be protecting the rule of law in another country,” Daw said.

Politically, Daw said, the president might be reluctant to “throw one of their own to the wolves in another country”.

But the options open to the Americans aren’t binary – they can still uphold the immunity of their citizen while taking steps to address the anguish of the Dunn family.

Daw adds: “The really right thing for them to do is to apologise to the family, write a serious letter of condolence and offer compensation but there’s no requirement on them to do that.” 

Even if Trump declines to waive Sacoolas’ diplomatic immunity, however, Dunn’s family would still have some potential avenues for legal recourse, and the family’s lawyer and spokesman, Radd Seiger, said that Dunn’s parents were engaging lawyers to take a civil case against Sacoolas in America.

There’s also the possibility that Sacoolas’ conscience gets the better of her and she returns to the UK of her own accord.

“The Vienna Convention states immunity is removed after the end of the diplomatic appointment so given that she and her husband have left the UK, one assumes they no longer have any diplomatic accreditation,” said Barker.

And there is also one more, and far more dramatic, option open to Dunn’s family – suing the US government itself in a UK court.

“What they would have to do, and it’s not going to be easy, is in the UK they would have to show attribution – that Sacoolas’ actions could be attributed to the US,” Barker said.

“Now, that might be a stumbling block if they were purely private acts. However, given that the immunity belongs to the US, you could argue that it’s the US that should be the respondent in this case.

“The US would normally have immunity under the State Immunity Act (SIA), but there is a clear exception in the SIA for cases involving personal injury and death.”

On Friday, Harry’s auntie Katie Grant and family friend Nicola Watson told the PA News Agency they would be launching a green ribbon campaign around the area where he lived in memory of the teenager.

She said: “Grief doesn’t come close to what I’ve felt to be honest with you.

“I’ve never had anyone young and so close actually go. When you’re older you kind of accept that they’ve had their life.”