Lawyers for the Duchess of Sussex say the publication of Meghan's letter to her estranged father Thomas Markle was "a triple-barrelled invasion of her privacy rights".
The Duchess' legal team returned to the courtroom on Tuesday in the latest hearing for Meghan's privacy claim against Associated Newspapers Ltd (ANL).
During the remote hearing in front of Mr Justice Warby over two days, the court will hear an application for summary judgment – a legal step which would see the case resolved without a trial – when Meghan's legal team will argue that ANL's defence has no prospect of succeeding at a trial.
If successful, the case will then be closed, negating the need for a full trial.
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Meghan, 39, is suing Associated Newspapers Ltd for breach of copyright, infringement of her privacy, and breaches of the Data Protection Act over articles which showed parts of a letter she had written to her father, 76-year-old Thomas Markle, in August 2018.
However, ANL claims Meghan wrote the letter "with a view to it being disclosed publicly at some future point".
The Duchess' full claim was due to be heard at the High Court this month, but last year the case was adjourned until autumn 2021 for a "confidential" reason.
On Tuesday, Justin Rushbrooke QC, representing the Duchess, described the hand-written letter as "a heartfelt plea from an anguished daughter to her father", which Meghan sent to Mr Markle "at his home in Mexico via a trusted contact … to reduce the risk of interception".
He said the "contents and character of the letter were intrinsically private, personal and sensitive in nature" and that Meghan therefore "had a reasonable expectation of privacy in respect of the contents of the letter".
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Harry and Meghan pictured in March 2020
During the hearing it emerged that the Duchess had told her estranged father in the last line of the letter she wrote him: "I ask for nothing other than peace and I wish the same for you."
Mr Rushbrooke said in written submissions: "It is as good an example as one could find of a letter that any person of ordinary sensibilities would not want to be disclosed to third parties, let alone in a mass media publication, in a sensational context and to serve the commercial purposes of the newspaper."
He added that ANL "has no viable defence" to Meghan's claim for misuse of private information.
The letter was sent to Meghan's father in August 2018
ANL said in its response that the case was "wholly unsuitable for summary judgment".
Antony White QC, representing ANL, said there was "uncertainty as to a number of significant factual matters which can, and should, be investigated at trial when the court will have the full picture in terms of disclosure and evidence".
Mr White also referred to the involvement of the Kensington Palace communications team before the letter was sent, saying: "No truly private letter from daughter to father would require any input from the Kensington Palace communications team."
In relation to Meghan's copyright claim, Ian Mill QC, representing the Duchess, argued that "she and she alone" created a draft of the letter to her father "which she then transcribed by hand".
Mr Mill said the letter was "a heartfelt expression of sentiment, it's opinion, it's emotional", adding that it was the product of "some considerable intellectual effort".
Finding Freedom was published in August 2020
A judge ruled in September that the Mail On Sunday can rely on a recent royal biography Finding Freedom in its defence to Meghan's privacy claim.
The Duchess subsequently lost the bid to appeal such an inclusion during a hearing in October.
However, the publisher's attempts to name five of Meghan's friends who gave an anonymous interview to People magazine – which ANL says brought the letter to her father into the public domain – was dismissed last August.
The remote hearing before Mr Justice Warby is due to continue on Wednesday and it is expected he will reserve his judgment to a later date.
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