The Home Office has described the US Secretary of State's decision to reject an extradition request for the suspect charged in connection with the death of Harry Dunn as a "denial of justice".
The UK's Home Office said it was disappointed in the decision, which "appears to be a denial of justice".
The parents of the 19-year-old were informed of Mike Pompeo's decision in a phone call with their MP on Thursday, a family spokesman said.
"We are urgently considering our options".
Dunn was killed when his motorbike crashed into a vehicle outside a USA military base in Northamptonshire on 27 August 2019.
"At the time the accident occurred, and for the duration of her stay in the United Kingdom, the US citizen driver in this case had immunity from criminal jurisdiction", a State Department representative said in a statement.
Caroline Wozniacki Career Ends In Tears With Defeat At Australian Open
Jabeur was given a rapturous reception by the Melbourne Arena audience and embraced Wozniacki, which made her debut in 2005. Spanish legend Rafael Nadal also congratulated the Danish tennis star, labelling her career as "amazing". "Oh, my God.
India vs New Zealand T20I series: All you need to know
They play really hard and they want to win the game but at the end of the day they're not dejected or depressed if they don't win. Other than bringing their best game on the occasion, India will also have to adjust to the ground's dimensions.
Klopp praises Liverpool skipper Jordan Henderson following 2-1 win at Wolves
Fabinho was a regular starter for us before he got injured and against the Red Devils, the Brazilian made his return from injury. Roberto Firmino scored a late victor to take the Reds 16 points clear of Manchester City at the top with a game in hand.
The US State Department did not immediately respond to requests for comment.
They said they would react fully to the announcement on Friday, adding that "the fight goes on" for justice for their son.
Sacoolas, who has admitted to being the driver, was charged by British police with causing death by unsafe driving.
Charlotte Charles, mother of Harry Dunn, who was killed when his motorbike was struck by a vehicle, joined by husband Bruce Charles, in NY, in October. Team Harry will sit down with the Government tomorrow and work out our next steps.
Ahead of an October 9 phone call with Johnson, Trump was photographed carrying a briefing paper marked "secret" which indicated that if the prime minister raised the subject of Sacoolas, the president was to tell him that "the spouse of the U.S. Government employee will not return to the United Kingdom".
Sacoolas claimed diplomatic immunity and left Britain after the crash.