Prince Harry and Meghan Markle relocated to the US in 2020 after stepping down from their senior royal roles.
The couple have spoken about their decision to leave the UK, detailing the pressures they faced from the British press, as well as their fractured relationships with other members of the family, in their Netflix documentary Harry & Meghan.
The Duke of Sussex also opened up about everything from his childhood, to processing his grief following the death of his mother, the late Princess Diana, to his difficulties with Camilla, Queen Consort in his memoir, Spare.
However, his admission that he has taken drugs in the past could impact his US visa according to one lawyer.
In his book, Harry said that he had used experimental drugs to help him deal with the loss of his mother, and also shared an anecdote about taking magic mushrooms at Courteney Cox's house.
Now, US lawyer Samuel Dewey - speaking on behalf of conservative think tank The Heritage Foundation - has told Express.co.uk that this admission could impact Harry's visa if he had not declared it to authorities.
Dewey is campaigning for his visa application to be made public as he claims he is concerned that the Duke might have received 'preferential treatment'.
According to US immigration law, failure to declare drug use could result in deportation or a permanent ban from applying for citizenship.
While Dewey claims the foundation is not interested in whether or not Harry should get a waiver, he believes the details should be made public as 'if improper treatment has been given that's a huge concern as it relates to the enforcement of the law'.
It is unclear what visa Harry holds in the US, or the information related to his application as the details remain confidential as per the US Customs and Border Protection authorities and the State Department.
Prince Harry has not yet commented.
