The ruling that President Trump’s eldest daughter, Ivanka, will be forced to testify in her father’s civil fraud case will deliver to the stand a woman who once was at the center of her father’s presidential administration but has, along with her husband, held his re-election effort at arm’s length. 

Judge Arthur Engoron, in court Friday morning, rejected Ms. Trump’s efforts to quash her subpoena. He explained, “I want to see her in person. That is how we prefer testimony.” He added that “a trial is a search for the truth, and the law is entitled to every person’s evidence.”  

It could be a coup for the prosecutor, Attorney General Letitia James, who has already won summary judgment on the question of whether Mr. Trump, his two eldest sons — Donald Jr. and Eric — and their organization committed “persistent” fraud. The trial in which Ms. Trump must now testify is focused solely on tabulating damages, which could be substantial. 

Ms. Trump, who is married to Mr. Trump’s erstwhile senior adviser, Jared Kushner, will take the stand after a failed effort to avoid that outcome. She was previously a defendant in the case, as Ms. James alleged that she participated in the overvaluation of assets during her tenure as the Trump Organization’s executive vice president for development and acquisitions.

An appeals court dismissed the allegations against her, reasoning that her role predated the window for liability allowed by the relevant statutes of limitations. Ms. James, though, reckons that her testimony could be valuable in New York’s quest to exact the maximum damages — $250 million — from her family.

Ms. Trump, in her motion to quash the subpoena, called the request for her testimony a prosecutorial “end run” and accused the attorney general of “effectively trying to force” Ms. Trump “back into this case from which she was dismissed.” She pointed out that she, Mr. Kushner, and their three children have moved to Florida from New York, and that her involvement with the family business has attenuated. 

Judge Engoron was not convinced. He found that “Ms. Trump owns property in New York and has done business in New York,” threads of connection he viewed as substantive enough to subject her to the jurisdiction of a Lower Manhattan courtroom. The Supreme Court has held that jurisdiction is constitutional when “notions of fair play and substantial justice would not be offended.”

Ms. Trump’s lawyer, Bennett Moskowitz, objected on those grounds, calling Ms. James’s attempts to dragoon his client into testifying a “bridge too far” and arguing that the state’s argument “falls on its face.” Judge Engoron did not agree, but he did give Ms. Trump time to appeal, as her testimony will be scheduled for Wednesday, at the earliest. 

Prosecutors are likely to be especially interested in Ms. Trump’s work on the Trump International Hotel Washington, D.C., which closed last May, having occupied the Old Post Office property on Pennsylvania Avenue. She was the primary contact for lenders. Judge Engoron found the Trumps “liable as a matter of law for persistent violations” of New York’s fraud code with respect to that property, along with many others, including Mar-a-Lago.

The Trump International Hotel signed a 60-year lease but was sold in May 2022. It reopened as a Waldorf-Astoria hotel. While under the aegis of the Trumps during his presidency, its hosting of foreign dignitaries became a source of legal challenge on the basis of the Emoluments Clause, which ordains that no “Person holding any Office of Profit or Trust under [the United States], shall, without the Consent of the Congress, accept of any present, Emolument, Office, or Title, of any kind whatever, from any King, Prince, or foreign State.” 

In a court filing arguing for the indispensability of Ms. Trump’s testimony — one that evidently persuaded Judge Engoron — Ms. James maintains that the former president’s second eldest child “remains financially and professionally intertwined with the Trump Organization and other Defendants and can be called as a person still under their control.”

Both Mr. Kushner and Ms. Trump are estimated to be be worth in the hundreds of millions of dollars. Mr. Kushner is the heir to a sprawling real estate fortune, with properties strewn throughout New York and New Jersey. The couple recently bought a lot on Miami’s Indian Creek Island for about $32 million and are building a family estate there. 

One consolation to Ms. Trump regarding her compulsory testimony may be that once on the stand, she will be able to invoke the Fifth Amendment’s protection against self-incrimination. A century ago, in McCarthy v. Arndstein, the Supreme Court held that dispensation extends to civil cases as well as criminal ones.