Justice Fancourt ruled that 15 stories published about Prince Harry by MGN used unlawful information gathering methods such as phone hacking and the use of private investigators.
In all, 33 articles had been submitted for consideration, but the judge ruled fewer than half used unlawful information gathering.
The Duke of Sussex and three other claimants sued the British newspaper group, which publishes The Daily Mirror, The Sunday Mirror and Sunday People, alleging its journalists hacked his phone and used other illicit means to gather information about his life over a roughly 15-year period.
In a statement, the 39-year-old royal said “today is a great day for truth as well as accountability.”
“The court has ruled that unlawful and criminal activities were carried out at all three of Mirror Group’s newspaper titles (The Mirror, The Sunday Mirror and The People) on a habitual and widespread basis for more than a decade,” Prince Harry said.
“Today’s ruling is vindicating and affirming. I’ve been told that slaying dragons will get you burned. But in light of today’s victory and the importance of doing what is needed for a free and honest press – it’s a worthwhile price to pay. The mission continues.”
In a summary of his ruling, the judge said the publisher began to use phone hacking in 1996 and that from 2006 to 2011 the practice “was still extensive during those years” at MGN but the prince’s phone “was only hacked to a modest extent.”
The prince became the first senior member of the British royal family to give evidence on a witness stand in more than 130 years, when he appeared in the witness box back in June.
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MGN’s lawyer, Andrew Green, put the royal under forensic and detailed questioning, probing him on the specifics of his claims and occasionally left him scrambling to recall sections of his written statement or find pieces of evidence.
In June, Prince Harry told the courtroom the distress the press caused him during his youth, saying the articles published by the MGN played a “destructive role” in his adolescence.
The suit is just one of several that the Duke of Sussex has brought against major UK newspaper publishers, including Rupert Murdoch’s News Group Newspapers and Daily Mail publishers Associated Newspapers Limited.
This is a developing story and will be updated.