The US government has filed a motion to suppress the employment details of the woman accused of killing teenager Harry Dunn.
Anne Sacoolas’ car collided with the 19-year-old’s motorbike near RAF Croughton in August 2019.
Government lawyers asked a Virginia court to impose a protective order in response to a damages claim filed by Mr Dunn’s parents.
Family spokesman Radd Seiger said the order would be “resisted strenuously”.
Sacoolas, 43, and her husband were both US State Department employees at the time of the crash in Northamptonshire.
She was later charged with causing death by dangerous driving but an extradition request, submitted by the Home Office, was rejected by the US State Department last January.
Charlotte Charles and Tim Dunn, Mr Dunn’s parents, gave legal testimony earlier this month in their damages claim against Mr and Mrs Sacoolas.
Mrs Sacoolas’ deposition in the case is due next month.
The application for a protective order, filed on Friday, argues that “information concerning the United States Government has little to no relevance to an adjudication of any remaining issues in this case”.
It goes on to say: “The United States seeks protection … because of the impact the disclosure of information regarding the Government in this litigation could reasonably be expected to have on national security.”
Mr Seiger said: “We are analysing it and the family will be seeking legal advice from their US lawyers.
“It now appears that Mr and Mrs Sacoolas have brought in their employers, the US Government, to help them minimise what happened to Harry on the night he died in an attempt to prevent both the family and public at large from knowing the full truth.
“The US Government have asked the parents to consent to their application to court, who in turn have told them it will be resisted strenuously.”
Alexandria District Court in the US state of Virginia heard the couple’s intelligence work was a “factor” in their departure from the UK – with the Sacoolases leaving for “security reasons”.