Meghan Markle felt "unprotected" by the British royal family during her pregnancy with son Archie, she says in new court documents.© Karwai Tang/WireImage Meghan Markle
The documents surfaced Wednesday as part of Meghan and Prince Harry's lawsuit against a British media company claimed that the Duchess of Sussex, 38, was "prohibited from defending herself" by the monarchy against media intrusion.
"The Claimant had become the subject of a large number of false and damaging articles by the U.K. tabloid media, specifically by the Defendant, which caused tremendous emotional distress and damage to her mental health," according to the new documents filed by Meghan's legal team.
"As her friends had never seen her in this state before, they were rightly concerned for her welfare, specifically as she was pregnant, unprotected by the Institution, and prohibited from defending herself," the documents continue.
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Meghan, 38, is suing publishers Associated Newspapers and the Mail on Sunday for publishing extracts of what she describes as a "private and confidential" letter sent to her father, Thomas Markle, in August 2018 — three months after her wedding to Prince Harry, 35.
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"This case centers on a private and hand-written letter from a daughter to her father that was published by The Mail on Sunday," a source close to the couple tells PEOPLE. "This gross violation of any person's right to privacy is obvious and unlawful."
The existence of the letter was first publicly disclosed in a PEOPLE story in which five of Meghan's friends spoke out against the "global bullying" they said was aimed at the Duchess of Sussex. In the new court documents, Meghan says she did not authorize her friends to speak to PEOPLE, nor was she aware of the story in advance.
After the PEOPLE story was published, The Mail on Sunday published the letter Meghan had written to her father.
"The Duchess’ rights were violated; the legal boundaries around privacy were crossed," the source adds. "Throughout this process, the extremes to which The Mail on Sunday used distortive, manipulative and dishonest tactics to target The Duchess of Sussex have been put on full display."
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Following a pre-trial hearing in April, to which Meghan and Harry listened in from their home in Los Angeles, the legal case will focus on whether the Mail on Sunday infringed on Meghan's privacy and U.K. laws surrounding copyright and data protection by printing excerpts of a handwritten letter she sent to her father in August 2018.
The lawsuit is expected to go to a full trial in late 2020 or early 2021.© Provided by People Samir Hussein/WireImage Meghan Markle and Prince Harry
Meghan and Prince Harry announced on April 19 that they and their representatives will not deal with four U.K. outlets, announcing "there will be no corroboration and zero engagement" in a letter to the editors.
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The Duke and Duchess of Sussex said they fundamentally disagree with the "style of reporting" of four tabloids —The Sun, The Daily Mail, The Mirror and The Express — which they say have "pulled apart" the lives of many individuals.