Attorney Charles Harder, who is representing Robert Trump—the brother of President Donald Trump—in a lawsuit seeking to block publication of Mary Trump's upcoming book about the president and his family, argued that Mary Trump is still bound by a confidentiality agreement even though her uncle has been elected president.

In a reply brief asking for a preliminary injunction late Tuesday, Harder argued that the book's publisher, Simon & Schuster, should not have hurried toward publication after receiving notice that Mary Trump had signed a confidentiality provision of the 2001 settlement agreement associated with her grandfather Fred Trump's will, which prohibited her from publishing information about the president, Robert Trump and their sister, former Judge Maryanne Trump Barry of the U.S. Court of Appeals for the Third Circuit, without the trio's consent.

Attorneys representing Mary Trump and Simon & Schuster have argued that Mary Trump's right to publish is protected by the First Amendment and that court orders blocking publication of the book are a form of prior restraint.

Mary Trump remains under a temporary restraining order imposed by Dutchess County Supreme Court Justice Hal Greenwald, whose TRO against Simon & Schuster was lifted by an appellate court judge July 1. Mary Trump's attorney, Gibson, Dunn & Crutcher partner Theodore Boutrous, has argued the publisher is acting independently and that she is unable to stop the book's release.

Days before Robert Trump filed suit, the Department of Justice sued former national security adviser John Bolton to block publication of his White House memoir days before publication. A federal judge found that the horse was "out of the barn" at that point, because Bolton's book had been widely distributed and reviewed in the press.

Harder built on the horse metaphor, noting that Simon & Schuster recently moved the planned publication of the book up to July 14 from July 28. Several major news organizations obtained copies of the book and published details about its contents Tuesday.

"In fact, Simon & Schuster, knowing full well that the owner of the horse had signed an agreement not to let him out, snuck out to the stables at midnight and deliberately let the horse out anyway," he wrote.

Harder argued that Mary Trump's observations about her relationships with the Trump siblings are not a form of political speech.

"Even as to Donald Trump, who became president 15 years after the settlement agreement at issue was formed, her descriptions and accounts of her "relationship" with Donald Trump are personal observations, not political commentary," Harder wrote, adding that the president's niece is free to express her opinions on politics and the president's performance in office.

If anyone can break a contract to speak about material "relevant to the election," Harder argued, nothing would stop lawyers or psychotherapists from breaking their professions' confidentiality rules to discuss their communications with people running for office.

First Amendment arguments set forth by Simon & Schuster and in amicus briefs have relied on a false analogy between book publishers and newspapers, Harder argued.

"Book publishers do not passively receive, from sources, information independently obtained (perhaps sometimes through wrongful means)," he wrote. "Rather, book publishers pay their authors to create books under lucrative publishing contracts; the manuscripts are then edited by employees of the publisher, as well as the author, in a collaborative process before publication."

Boutrous dismissed Harder's arguments in a statement late Tuesday.

"Robert Trump's brief defies the First Amendment, ignores basic contract law and fails completely to justify a prior restraint muzzling Mary Trump from publishing her book and engaging in core political speech about the President based on her own experiences and observations," he said.

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