Meghan Markle has declared victory in her battle against the U.K.’s Mail on Sunday for invading the Duchess of Sussex’s privacy by publishing a letter she wrote to her estranged father.

On Thursday, Judge Mark Warby said Associated Newspapers misused the 39-year-old’s private information in five February 2019 articles in the British tabloid and on the MailOnline website, which published portions of a handwritten letter to former Hollywood lighting director Thomas Markle, after her 2018 royal wedding to Prince Harry.

The judge said the duchess "had a reasonable expectation that the contents of the letter would remain private. The Mail articles interfered with that reasonable expectation."

The ruling is a significant victory for the duchess, who sued the publisher for invasion of privacy and copyright infringement.

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Thomas Markle (right), father to Meghan Markle, Duchess of Sussex (left). (Getty Images/Mega)

Associated Newspapers contested the claim, and a trial was scheduled for the fall. The duchess asked for a summary judgment to settle the case without a trial.

At a hearing last month, Markle’s lawyer, Justin Rushbrooke, argued that the publisher had "no real prospect" of winning the case.

The star's lawyers say the "deeply personal" five-page letter was intended for her father alone.

But the defense argued Markle wrote the letter as part of a media strategy to rebut a negative view conveyed by her father, and with help from the communications team in the royal couple’s Kensington Palace office.

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Meghan Markle currently resides in California with her husband Prince Harry and their son Archie. (Getty)

Thursday’s ruling means Markle has won her case on privacy grounds, but the judge said a "limited trial" should be held to decide some of the copyright issues.

Markle, an American actress and star of TV legal drama "Suits," married Harry, a grandson of Queen Elizabeth II, at Windsor Castle in May 2018. Their son, Archie, was born the following year.

In early 2020, the royal couple announced they were quitting royal duties and moving to North America, citing what they said were the unbearable intrusions and racist attitudes of the British media. They recently bought a house in Santa Barbara, California.

The Associated Press contributed to this report.