The duchess had already won the majority of her claim against Associated Newspapers, which also owns the MailOnline website, relating to five 2019 articles that published parts of a letter show wrote to her father after her 2018 wedding to Prince Harry.
A High Court Judge ruled in her favour in February after deciding the publication of large parts of the handwritten letter was “manifestly excessive” and unlawful. They also granted Meghan’s request for a summary judgment to settle the case – meaning she won that part of the case without having to go to trial.
However the court did not decide whether Meghan was the “sole author” and copyright holder of the letter at the time.
But on Wednesday, the judge sided with Meghan’s lawyers regarding the remaining parts of their copyright claim, after lawyers representing the Queen refuted the claim made by the defence that the letter’s copyright belonged to the Crown.
The newspaper group had initially said it thought the letter had been co-authored by Jason Knauf, the duke and duchesses’ former communications secretary, and thus was the property of the royal household.
The duchess’ lawyer Ian Mill told the court that lawyers for Mr Knauf had confirmed he did not write the letter, and that the defence’s case had “been shown to be completely baseless.”
In his ruling in February, judge Mark Warby said the public disclosure of Meghan’s “personal and private letter” to her father Thomas Markle was “manifestly excessive and hence unlawful”.
“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,” he said. “These are inherently private and personal matters.”
Gerard Cukier, a litigation partner at Keystone Law who were uninvolved in the case, said it would be difficult to challenge the strength of the judgements handed down in the court of appeal.
It comes after the Duchess, who stepped away from royal life along with Prince Harry last year, had her initial claims against the newspaper group dismissed by a judge.
“Having started the fight against the Mail on Sunday badly and losing the first couple of rounds, the Duchess of Sussex has come back swinging. She has won every subsequent court application and finished with a complete knockout of the Mail on Sunday’s case,” he said.
“While we are still waiting to hear whether Associated Newspapers are appealing to the Court of Appeal, successfully challenging Lord Justice Warby’s strong judgments will be difficult.”
Additional reporting by AP