The Duke of Sussex's visa application should be made public in light of recent drug use revelations, according to a conservative think tank's appeal, which will be heard by a US judge.
Tuesday in Washington, DC, there will be a federal court hearing that is open to the media.
In his memoir Spare, which was published in January, Prince Harry discussed using marijuana, cocaine, and psychedelic mushrooms.
This is crucial because, despite the fact that the situation is more complicated, prior drug use may be used as a reason to reject a US visa application.
The US hearing is separate from Harry's UK trial regarding alleged newspaper phone hacking.
The Heritage Foundation, a well-known Washington, DC-based think tank that has historically had a significant influence on US public policy, filed the lawsuit.
The foundation claims in the lawsuit that "widespread and continuous" media coverage of Prince Harry's acknowledged drug use has raised concerns about the government's due diligence and the procedures it followed when it granted him entry to the country.
Following the announcement that he and his wife, Meghan Markle, would no longer be performing royal duties, the duke relocated to the US in January 2020.
In a statement, the Heritage Foundation added that it hoped to determine whether "celebrity elites" were receiving preferential treatment and whether the Department of Homeland Security (DHS) was conducting itself "fairly - without fear or favor.".
DHS stated in its response to the lawsuit that the Heritage Foundation had not proven a need for the prompt release of the documents. The government asserted that there was no evidence of "widespread" public interest in viewing the immigration records.
US Customs and Border Protection denied the foundation's earlier, initial request because they required Prince Harry's permission to release his information, according to their justification.
A comment from DHS has been requested by the BBC.
Prince Harry, who is now 38, has acknowledged using drugs both as a teen and an adult. He admitted using cocaine as a teenager and smoking marijuana while a student at Eton in Spare. In the UK, neither drug is permitted.
In his account of using cocaine, he said, "It wasn't much fun, and it didn't make me particularly happy, as it seemed to make everyone around me.". But the main objective was achieved because it did make me feel different. ".
On a trip to California in 2016, he also spoke about consuming psychedelic mushrooms. Although some cities have decriminalized its use, the drug is still illegal in the state.
Since the publication of Spare, interviews have featured similar admissions of drug use.
A comment from the duke has been requested by the BBC.
The use of illegal drugs may, in theory, be grounds for denial of both immigrant and non-immigrant visa requests. These applications' application forms specifically inquire about the applicant's current and past drug use as well as whether they are a "habitual drunkard.".
It is unknown what kind of visa Prince Harry has for the United States. US citizen Ms. Markle is.
According to official US Citizenship and Immigration Services policies, visa applicants "who are found to be drug users or addicts" are ineligible. In actuality, immigration officers are given a great deal of discretion to decide based on various aspects, such as the quantity and intensity of drug use.
In cases where an applicant has acknowledged using drugs, waivers are also an option.
The majority of the time, doing so necessitates a "pretty formal rehabilitation programme," follow-up appointments with a doctor, and a year - or more - without any drug use, according to Stacy Cozart Martin, an immigration lawyer and adjunct law professor at Case Western Reserve University.

Even then, she added, it was up to the [immigration] officer's discretion whether they wanted to let you enter or not.
Perhaps another consideration in Prince Harry's visa application was his celebrity status.
According to Ms. Martin, much immigration is voluntary. They probably will also be given a little bit more wiggle room than the typical person. " .
Eileen Blessinger, an immigration lawyer in Virginia, said that immigration officials deciding on any applicant's entry to the US - or potential removal - would also have to weigh the benefits of letting that person in regardless of past transgressions.
She added that there might be both an economic and a cultural impact on the US. That will all "heavily weigh in favor of getting someone a waiver,".
A visa may be revoked if there are any lies or misrepresentations on the application.
It's unclear when the judge will decide whether or not the documents can be made public. The Heritage Foundation has stated that it expects the situation to be resolved within a few weeks.
Following the hearing on Tuesday, a press conference will be held by the think tank's representatives.
The judge is unlikely to concur with the Heritage Foundation's lawsuit, according to immigration attorneys and experts.
Ms. Martin and Ms. Blessinger both stated that they had never heard of immigration records being made public and cautioned that doing so in the case of Prince Harry would probably have far-reaching consequences in the future.
Such a thing has never crossed my mind. These applications contain an enormous amount of personal data, according to Ms. Martin.
She continued, "If that were to be released to the public, it would be very, very shocking and I think a little frightening.". "For everyone, not just for him.
. "