The family of Harry Dunn was informed that the allegations of abuse of power by Foreign Minister Dominic Raab were "totally unfounded".
The Foreign Office (FCO) "will oppose and seek costs" for any judicial review, as the family has "not identified a reasonably arguable ground of court challenge," the media reports. AP.
It is understood that a legal claim issued by Harry's family on October 25 was met with strong resistance on the part of the FCO, who stated that any judicial review would be "opposed" and "defended" .
The 19-year-old's parents had asked the FCO to "withdraw the advice" given to the Northamptonshire police regarding the granting of diplomatic immunity to the American suspect in the case of Anne Sacoolas.
The family's lawyers also made an alternative claim to "pay material damages" for the charges of violation of the European Convention on Human Rights.
The teenager was killed when his motorcycle was involved in a car crash in front of the RAF in Croughton, Northamptonshire, on August 27th.
Ms. Sacoolas, the alleged motorist responsible for the accident, invoked diplomatic immunity.
She was then allowed to return to the United States.
The complaint against the FCO issued on behalf of Dunn's parents, Charlotte Charles and Tim Dunn, alleged that the diplomatic immunity granted to Ms. Sacoolas was "wrong in law".
In the FCO's response, seen by the PA, the family was informed that the allegation was not accepted.
They also learned that the accusations that Foreign Minister Dominic Raab had "committed mischief" were also totally unfounded.
Family spokesman Radd Seiger said the FCO's response had been received and that it was being digested with lawyers.
In its letter, the FCO wrote: "It is not accepted that the application for judicial review proposed on behalf of your clients in your letter of October 25 identifies any reasonably justifiable reason for court challenges.
"It is therefore not acceptable for you to have identified any arguable basis for suggesting that the FCO should now either" withdraw the advice provided to the police ", or" pay damages for the prejudice suffered on the ground violation of Articles 2 and 6 of the ECHR. & # 39 ;.
"The unprecedented allegation that the Secretary of State for Foreign and Commonwealth Affairs (SSFCA) abused his power and / or abused his power and / or committed a breach of the law in the performance of his duties is entirely unfounded. "
The answer continued as follows: "With regard to the alternative ground of appeal based on Articles 2 and 6 of the ECHR, it is not accepted that you have identified a ground for criticizing the actions of the SSFCA.
"The SSFCA therefore refuses to take the action you have asked it to take on behalf of your clients and would oppose any application for leave to file an application for judicial review.
"We therefore invite you not to proceed with the proposed claim.If the claim is issued, it will be defended, the claim will be challenged and the Secretary of State will claim the cost."
In a statement on Twitter, Mr Seiger added: "The FCO relies on two private agreements concluded in 1995 and 2001 between the United States and the United Kingdom to argue that Anne Sacoolas was enjoying the same status as the other. a diplomatic immunity, in response to the complaint of the family of Harry Dunn against them advice to @nothantspolice.
"After taking the advice of a legal advisor, the family's position is clear: these arrangements have no legal basis and, as Dominic Raab himself said in his statement in the House of Commons, they have never been tested by the courts.
"As it was not enough for the family to suffer the loss of Harry, the British government now seems to want to make it undergo a long and unnecessary judicial battle ending in court. will not rest until justice is done, but shame on the government. "
Report by PA.