The parents of Harry Dunn will seek a judicial review of the way his case was handled, according to Sky News.
The teenager was killed while riding his motorbike on roads near RAF Croughton in Northamptonshire on 27 August. He was involved in a collision with a car driven on the wrong side of the road.
Shortly after his death, Anne Sacoolas - the wife of a US intelligence officer based at the airfield - was granted diplomatic immunity to return to America.
She had been questioned over the death and has since apologised for causing it.
Charlotte Charles and Tim Dunn, Harry's parents, have been campaigning for Mrs Sacoolas to return to the UK since the 19-year-old's death.
That included a trip to the USA and a meeting with President Trump.
In the past week, Northamptonshire Police officers have been sent to the US to question Mrs Sacoolas under caution, a move also criticised by Mrs Charles and Mr Dunn.
They have referred the case to the Independent Office for Police Conduct.