PrinceHarry, the younger son ofKing Charles III, will take the stand Wednesday in a London courtroom.
Harry is scheduled to testify in the privacy invasion case against publisher Associated Newspapers Limited, the publishers of the Daily Mail and Mail on Sunday.
He is the first witness to be called in the trial, which began Monday.
The Duke of Sussex, along with six other parties including musician Elton John and actress Elizabeth Hurley, have accused Associated Newspapers of illegal information-gathering practices.
Prince Harry returns to UK for 1st day of tabloid court case
They have specifically accused the publisher of allegedly hiring private investigators who they claim used unlawful means to gather information on them in the late 1990s and early 2000s, including secretly placing listening devices inside cars and homes and allegedly paying police officials for inside information.
Meghan Markle, Prince Harry share new family photo featuring Archie, Lilibet
Associated Newspapers is denying all allegations from the plaintiffs, calling them "preposterous" and says the claims are "unsubstantiated and highly defamatory" and "based on no credible evidence."
Harry traveled to the U.K. for the trial from California, where he lives full-time with his wifeMeghan, the Duchess of Sussex, and theirtwo children.
Harry and Meghan moved to California in 2020 after stepping away from their senior royal roles.
