President Trump’s younger brother filed a temporary restraining order on Tuesday in an attempt to block the publication of an unflattering tell-all book by the President’s niece, Mary L. Trump.

The filing, a copy of which was obtained by CNN, listed Robert S. Trump as the plaintiff. Mary Trump and the publisher of her forthcoming book, Simon & Schuster, were listed as defendants.

Robert Trump, who is represented by the President’s attorney, Charles Harder, argued in the filing that Mary Trump was breaking a confidentiality agreement by publishing the book.

The filing said that after the death of Fred Trump, litigation ensued over his will. As part of a settlement, the filing said, a confidentiality provision was agreed upon by all parties, including Mary Trump.

The New York Times was first to report the news of the temporary restraining order.

Ted Boutrous, the attorney representing Mary Trump, who has also represented CNN on First Amendment issues in the past, said in a statement that the legal move aimed to “suppress a book that will discuss matters of utmost public importance.”

“They are pursuing this unlawful prior restraint because they do not want the American people to know the truth,” Boutrous said. “The courts will not tolerate this brazen effort to squelch speech in violation of the First Amendment.”

Simon & Schuster describes Mary Trump’s book online as a “revelatory, authoritative portrait of Donald J. Trump and the toxic family that made him.”

The book, the publisher says, will shine “a bright light on the dark history of their family in order to explain how her uncle became the man who now threatens the world’s health, economic security, and social fabric.”

Adam Rothberg, a spokesperson for Simon & Schuster, said in a statement, “As the plaintiff and his attorney well know, the courts take a dim view of prior restraint, and this attempt to block publication will meet the same fate as those that have gone before.”

“In ‘Too Much and Never Enough: How My Family Created the World’s Most Dangerous Man,’ Mary Trump has written a compelling personal story of worldwide significance, and we look forward to helping her tell her story,” Rothberg added.

The Trump administration recently took legal action in an attempt to block the tell-all book of John Bolton, the former national security advisor.

But a federal judge denied the Department of Justice’s motion, writing in his decision that Bolton’s book had already been widely distributed and that the court would “not order a nationwide seizure and destruction of a political memoir.”

Harder, the attorney representing Robert Trump, has a history of filing lawsuits against news organizations on behalf of President Trump. The lawsuits have been dismissed by legal experts as public relations stunts with little chance of success in court.