The Duke of Sussex admitted to taking cocaine, marijuana, and psychedelic mushrooms in his book Spare

Prince Harry’s “unique” US visa drugs lawsuit should be reopened due to secrecy around the Biden administration’s private submissions to the judge, a think tank has claimed.

The Duke of Sussex’s US visa documents were at the centre of a court battle since he admitted to taking illegal drugs, including cocaine, marijuana and psychedelic mushrooms, in the UK and America in his memoir Spare.

The Heritage Foundation, a conservative think tank, previously took legal action against the Department of Homeland Security (DHS) in a bid to force officials to release Harry’s visa documents.

The organisation wanted to see if the royal admitted to using illegal drugs before gaining a US visa.

Prince Harry’s US visa documents have not been made publicGetty

The case was terminated in September after the Washington department successfully argued that Harry had a right to privacy.

However, the Heritage Foundation is now calling for the lawsuit to be reopened on the basis that it was not granted access to private submissions made by the Biden administration to the judge, Newsweek has revealed.

The think tank has just submitted an application to “vacate” that ruling and release private correspondence between the government department and the judge.

The court filing reads: “This Court should vacate its opinion and order, enter all ex parte correspondence on the docket, unseal ex parte correspondence consistent with the Opinion.”

Whilst the judge acted to prevent the duke’s privacy being breached, the think tank argued that this hindered their ability to fight their case.

This “severely compromises [Heritage’s] ability to prepare arguments on appeal”, lawyers said.

They also claimed that there was “ample evidence of agency bad faith”, stating: “[Heritage lawyers] of course are not blind to the fact that they have brought a unique case that is fraught with these complexities. [Heritage lawyers] simply submit that the way forward taken by the Court does not comport with our adversarial system.

“[Heritage lawyers] simply submit that the way forward taken by the Court does not comport with our adversarial system.”

The lawsuit was brought by The Heritage Foundation against the DHS after a Freedom of Information Act request was rejected.

Prince Harry’s US visa case has been quietly terminated GETTY

According to the think tank, the release of the royal’s visa documents was of “immense public interest”.

However, Judge Nichols said the public’s interest in Harry’s immigration records is “outweighed by the duke’s privacy interest”.

He said: “Public disclosure of records about a single admission of a foreign national in the circumstances described above would provide the public, at best, limited information about the department’s general policy in admitting aliens.

“And the marginal public benefit of knowing that limited information is outweighed by the privacy interest the duke retains in his immigration status and records.”

In his memoir, the duke said cocaine “didn’t do anything for me”, but: “Marijuana is different, that actually really did help me.”