Harry Dunn's family has filed a civil claim for damages in the state of Virginia against his alleged killer.
Anne Sacoolas, 43, was charged with causing the teenager’s death by dangerous driving following a fatal road crash outside RAF Croughton in Northamptonshire on August 27 last year.
She claimed diplomatic immunity following the crash and was able to return to her home country, sparking an international controversy.
The suspect was charged by the Crown Prosecution Service in December but an extradition request submitted by the Home Office was rejected by the US State Department the following month.
The civil claim announcement comes ahead of the family's meeting with the Director of Public Prosecutions as the Attorney General is considering the possibility of trying Ms Sacoolas virtually or in her absence.
Their spokesman Radd Seiger said Mr Dunn’s alleged killer had “inexplicably” made no attempt to “resolve the dispute without having to go to court”.
Speaking ahead of the meeting with Max Hill QC, Mr Seiger told PA: “Ever since Harry’s family launched their campaign for justice last October, they have tried their level best to avoid any dispute with either Mrs Sacoolas herself, or the British or US governments.
“They came up against a brick wall at every turn and felt that they had no choice other than to launch their campaign.
“It remains the intention of the British authorities for Mrs Sacoolas to return to face the legal system in Britain and that is what she must do, self-evidently.”
Mr Seiger continued: “Harry’s parents are entitled to bring a claim for civil damages for Harry’s wrongful death in the US courts in Virginia.
“They have sought to avoid a formal dispute with Mrs Sacoolas so as not to put the parents through any additional unnecessary stress.
“Inexplicably, there has been a total failure on Mrs Sacoolas’s part to enter into the spirit of attempting to resolve the dispute without having to go to court.
“The parents have therefore, yet again, been forced to take yet another battle on since Harry’s death and have today filed a formal complaint against Mrs Sacoolas in the Virginia court.”
He added: “The parents wanted none of this. They have worked hard to avoid this. Mrs Sacoolas and her advisers clearly do not consider the further misery this imposes on Harry’s family.
“They have already been through so much; however, they are more than capable of taking this battle on.
“However, right-minded people on both sides of the Atlantic will rightly be appalled and horrified.”
Additional reporting by PA Media.
