A hearing on Prince Harry immigration records was due to be held in Washington, DC Federal Court in front of a U.S. Federal Judge on Tuesday.
The hearing on the petition filed by The Heritage Foundation's Oversight Project will be open to the press.
The organization is seeking information from the government authorities whether the Duke of Sussex receive preferential treatment from the US government.
The hearing comes at a time when Prince Harry is in the United Kingdom to testify before London High Court in his case against a newspaper group.
It's not clear whether the Duke of Sussex would be represented by his lawyers in the US.
It is also not known whether it's mandatory for Harry to appear before the US judge.
The conservative group said Prince Harry admitted in his book, Spare, to being a prolific drug user. In its complaint the organization said under the "U.S. immigration law, you can’t come in if you admit to a drug crime. You can only come in temporarily if you get a waiver."
Meanwhile, the Duke of Sussex arrived at London's High Court on Tuesday where he will give evidence in his lawsuit against the publisher of British tabloid the Daily Mirror, which he accuses of phone hacking and other unlawful acts.
He failed to appear in court as expected on Monday, but will entered the witness box on Tuesday.
MGN, now owned by Reach (RCH.L), apologised at the start of the trial for one admitted occasion that the Sunday People had unlawfully sought information about Harry, accepting he was entitled to compensation.
Prince Harry and Meghan Markle's confidence tracked at Invictus Games
Prince Harry's dour expression sparks rumors of tense date night with Meghan Markle
Meghan Markle's Royal endorsement sparks revival of 'Pamela Anderson Hair'
Kate Middleton kicks off the weekend with sporting spirit at Stade de Marseille
Prince and Princess of Wales find harmony between family and Royal duties
King Charles's tribute to Queen Elizabeth draws criticism