Meghan Markle has waged a legal battle against a British newspaper for publishing a confidential letter she wrote to her father, Thomas Markle, at the height of their fractured relationship.

The United Kingdom’s High Court held its first hearing in the privacy lawsuit last month and a legal expert told Fox News the courtroom drama will become heightened if and when the Duchess and her estranged father testify against each other.

“The big battle is going to be between Meghan and her dad. That will be horrible for both of them, I suspect,” Amber Melville-Brown, head of media and reputation at legal firm Withers, told Fox News in an interview.

This case is all about whether [Meghan] had a reasonable expectation of privacy. This means she’ll have to give evidence as to what she did with the letter and the impact [the publishing of it] had on her. The court won’t know how deeply distressing this is to her unless she gives evidence,” explained Melville-Brown, who is dual-certified in both the U.K. and New York.

It’s a bold move for the Duchess of Sussex, who, alongside husband Harry, has voiced disdain for the couple’s personal matters and recent departure from the royal family becoming tabloid fodder. Last month, the couple announced that they will no longer cooperate with certain British tabloids.

She is suing the Mail on Sunday’s publisher, Associated Newspapers, for copyright infringement and misuse of private information for releasing the contents of the letter. She also argues the publisher violated the U.K.’s data protection act.

The veteran privacy lawyer stressed the importance of protecting the privacy of clients but worries that Meghan Markle has already “overbaked the litigation cake” by taking news coverage too personally. Melville-Brown says that the lawsuit may lead to a win when it comes to copyright infringement, but it won’t put an end to the public’s interest in her private life.