EXACTLY WHICH detail in the tell-all book by a former adviser and confidant of first lady Melania Trump prompted the Justice Department to take the extraordinary action of suing the author? Was it Ms. Trump’s dislike of her stepdaughter? Her nonchalance about her husband’s behavior and lewd comments about women? Her obsession with her image? As titillating as some of those revelations may be — and embarrassing to President Trump and his wife — they are not matters of national security or information that is classified. It is alarming to see the Justice Department used yet again to retaliate against people who are exercising their First Amendment rights.

The Justice Department filed suit Tuesday in federal court against Stephanie Winston Wolkoff, a onetime friend of Ms. Trump, alleging she violated a nondisclosure agreement she signed when she volunteered in the East Wing in 2017. The book, “Melania and Me: The Rise and Fall of My Friendship With the First Lady,” sketches an unflattering picture of the first lady, buttressed by the release of tapes secretly recorded of Ms. Trump. “Who gives a [expletive] about the Christmas stuff and decorations?” she was recorded as saying, expressing her frustration at being criticized for the administration’s family separation policy at the same time she was expected to perform the traditional duties of the first lady, such as overseeing holiday decorations for the White House. The suit seeks to claim all proceeds from the sale of the book.

The lawsuit is the Justice Department’s latest effort to try to block damaging disclosures about Mr. Trump. Last month, it moved to replace Mr. Trump’s personal lawyers with government attorneys in a defamation suit brought against him by a woman who accused him of raping her in a department store in the 1990s. It sued unsuccessfully to block publication of former national security adviser John Bolton’s scathing memoir and now seeks to seize Mr. Bolton’s advance.

In Mr. Bolton’s case, there is at least some claim to be litigated about the possible disclosure of classified information. No such argument can be made about Ms. Winston Wolkoff. Material in her book is the standard fare of memoirs that have come to be somewhat of a tradition by former White House aides and are clearly protected by the First Amendment.

Mr. Trump thinks the rules — and constitutional amendments — don’t apply to him. From the start of his administration, indeed, even before he took office, he has wielded nondisclosure agreements, common in the private sector but unheard of in government, to try to silence people. His campaign is in litigation with former aide Omarosa Manigault Newman, who signed such an agreement in 2016 and wrote a book that characterized Mr. Trump as a racist. Mr. Trump’s family tried unsuccessfully to stop publication of Mary Trump’s book, “Too Much and Never Enough: How My Family Created the World’s Most Dangerous Man,” on grounds she, too, violated a nondisclosure agreement.

An attorney for Ms. Winston Wolkoff called the suit “meritless,” and we hope the court moves quickly to dismiss it. That will not undo the disgrace of Attorney General William P. Barr allowing the Justice Department to be used to bully Mr. Trump’s — and now his wife’s — critics.

Read more: