Prince Harry’s battle against the British tabloids reaches a critical juncture next week as the Duke of Sussex prepares to take the stand at London’s High Court in his privacy lawsuit against the publisher of the Daily Mail.

The 41-year-old prince joins singer Elton John, actress Liz Hurley, and four other public figures in suing Associated Newspapers over allegedly unlawful newsgathering practices during the late 1990s and early 2000s.

The lawsuit, filed last year, alleges the company hired private investigators to plant listening devices in cars and homes, hack voicemail messages, and bribe police officials for confidential information. The claimants also accuse Associated Newspapers of obtaining private medical records and flight details through impersonation, a practice known as “blagging.”

The trial commences Monday and Prince Harry is expected to spend a full day on the stand on Thursday, according to a draft trial timetable. Sir Elton, Ms. Hurley, and Baroness Doreen Lawrence are also likely to give evidence during the nine-week trial. The remaining claimants include Sir Elton’s husband, David Furnish, a former member of British parliament, Simon Hughes, and actress Sadie Frost. 

Associated Newspapers has vociferously denied all allegations, dismissing the claims as “lurid” and “simply preposterous.” The publisher is expected to call current and former editors and senior journalists to the stand, including the former longtime editor of the Daily Mail, Paul Dacre. 

The financial stakes are high. Any losing claimants will be responsible for covering the paper’s legal costs, which could come out to tens of millions of pounds. In December two judges urged the claimants to gain the “clearest possible understanding” of the penalties they may face if they are unsuccessful. 

The trial marks a significant development in Prince Harry’s campaign to hold the British press accountable for privacy violations and follows his successful actions against Mirror Group Newspapers and Rupert Murdoch’s News Group Newspapers.

Prince Harry’s case against Mirror Group — during which he became the first senior British royal in 130 years to give evidence in court — ended with the outlet paying substantial damages, covering the duke’s legal costs, and issuing an apology for past wrongdoing. His case against News Group Newspapers, publisher of The Sun, settled last January with similar terms.

News Group Newspapers faced public reckoning in 2011 when it came out that journalists writing for its now-defunct Sunday paper, the News of the World, had hacked the phones of high-profile figures in the pursuit of stories. The scandal triggered mass resignations and prompted a public inquiry that resulted in multiple arrests and convictions, including that of former News of the World managing editor Andy Coulson.

Prince Harry’s antagonism toward the British media traces to the death of his mother, Princess Diana, who was killed in a car crash in 1997 while fleeing a mob of aggressive paparazzi. Princess Diana endured relentless media harassment throughout her 17 years in the public eye, and her death sparked widespread condemnation of Britain’s tabloid culture. 

The duke and his wife, an American former actress, Meghan Markle, cite the media’s intrusive tactics as a factor in their decision to step back from royal duties and relocate to California in 2020.