The Duchess of Sussex has won her privacy lawsuit against the Mail on Sunday in the High Court, describing her triumph as a “comprehensive victory” against the newspaper’s “illegal and dehumanizing practices.”

Meghan filed the lawsuit against Associated Newspapers (ANL) for publishing excerpts from a letter she sent to her father.

Meghan, according to Judge Mark Warby, “had a reasonable expectation that the contents of the letter would remain private. The Mail articles interfered with that reasonable expectation.”

However, a trial may be held later to establish if the Duchess was the only author of the letter. It implies that officials nicknamed “the Palace Four” may still testify.

Mr Justice Warby awarded Meghan “summary judgment” in her claim for abuse of private information against the publisher of the Mail on Sunday and MailOnline, indicating that a portion of the case would be settled without a trial.

The High Court’s decision to grant the summary judgment means Meghan will no longer have to testify in her privacy lawsuit, avoiding a “face-off” with her estranged father, who was also scheduled to testify on behalf of the publisher.

“It was, in short, a personal and private letter,” said Mr Justice Warby. “The majority of what was published was about the claimant’s own behaviour, her feelings of anguish about her father’s behaviour – as she saw it – and the resulting rift between them. These are inherently private and personal matters.”

“The claimant had a reasonable expectation that the contents of the letter would remain private. The articles interfered with that reasonable expectation.”

Justice Warby added: ‘On an objective review of the articles in the light of the surrounding circumstances, the inescapable conclusion is… the disclosures made were not a necessary or proportionate means of serving that purpose. For the most part they did not serve that purpose at all.

‘Taken as a whole the disclosures were manifestly excessive and hence unlawful. There is no prospect that a different judgment would be reached after a trial.

‘The interference with freedom of expression which those conclusions represent is a necessary and proportionate means of pursuing the legitimate aim of protecting the claimant’s privacy.’

The Mail on Sunday’s publishers were “surprised” by the decision and were contemplating an appeal yesterday night. According to Mark Stephens of media law firm Howard Kennedy, this was the first judgment of this sort on a privacy issue in 20 years. “That has thrown the law into sufficient uncertainty,” he cautioned.

“People leak letters all the time and the question is whether you can report them or not.

According to this theory, it makes no difference what her motive was; it was her letter, it was private, and it was up to her whether she shared the information or not.

“So essentially what you have is a judicial endorsement of the ­ability to curate your reputation.

“It’s a good day for the rich and powerful who can afford expensive PR people to curate a false image which you then as a member of the media are unable to debunk. It effectively manacles the media from reporting on letters in the future.”

The Duchess of Sussex expressed gratitude to the courts for holding Associated Newspapers accountable.

“For these outlets, it’s a game. For me and so many others, it’s real life, real relationships, and very real sadness,” she said.

“The damage they have done and continue to do runs deep.”

“The world needs reliable, fact-checked, high-quality news. What the Mail on Sunday and its partner publications do is the opposite. We all lose when misinformation sells more than truth, when moral exploitation sells more than decency, and when companies create their business model to profit from people’s pain.

“But, for today, with this comprehensive win on both privacy and copyright, we have all won.”