Meghan, Duchess of Sussex, could face her father in the legal battle against a British tabloid that published parts of a private letter between her and her father, Thomas Markle. The Mail on Sunday, the paper that Meghan is suing, is planning to call her father as a "key witness" for the defense, its sister paper The Daily Mail reports.

The duchess sued the paper in October, claiming it illegally published a private letter she sent to her estranged father. The lawsuit accuses the tabloid and its parent company, Associated Newspapers, of misusing private information, infringement of copyright, and breach of a U.K. data protection act that went into force in 2018.

In an official statement announcing the lawsuit, Prince Harry said Meghan "has become one of the latest victims of a British tabloid press," and noted that the lawsuit hinges on only one instance in a "long and disturbing pattern of behavior by British tabloid media."

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Now, The Mail on Sunday has filed defense papers at the High Court in London that indicate Thomas Markle, 75, is prepared to give evidence against his daughter, The Daily Mail reports. Thomas Markle has provided lawyers for the paper with text messages he sent to the couple in the lead-up to their royal wedding in May 2018.

The BBC reports that Samantha Markle, Mr. Markle's daughter from his first marriage, said that if her father is called to testify, he will come to the United Kingdom.

In Prince Harry's statement, he claimed the paper "strategically" omitted certain paragraphs, sentences, and words "to mask the lies they had perpetuated for over a year." The paper responded to that claim, saying that the edited portions it released accurately conveyed the tone, content and meaning of the letter, the BBC reports.

The paper appears to be mounting the defense that Thomas Markle had a right to publish the letter. "(He) had a weighty right to tell his version of what had happened between himself and his daughter, including the contents of the letter," the paper claims, according to The Associated Press.

Furthermore, the paper argued that Meghan's actions show she was aware the letter would be seen publicly. In legal documents, the paper said the letter was "immaculately copied" in Meghan's "elaborate handwriting," implying she anticipated it would be read by an audience, the BBC reports.

"(The Royal Family) rely on publicity about themselves and their lives in order to maintain the privileged positions they hold and promote themselves," according to the paper's legal filing, which also notes, "There is a huge and legitimate public interest in the Royal Family and the activities, conduct and standards of behavior of its members."

It adds, "This extends not merely to their public conduct, but to their personal and family relationships because those are integral to the proper functioning of the monarchy."

Meghan is currently in Canada with her 8-month-old son Archie. She returned to Canada after the royal couple made the bombshell announcement that they will be stepping away from their "senior" royal roles and splitting their time between the U.K. and North America.