Two judges appointed by President Donald Trump have overturned a fellow Trump appointee and revived a whistleblower's Medicare fraud lawsuit, adding another chapter to a closely watched fight over how far private plaintiffs can go in enforcing federal fraud laws.

On Tuesday, a panel of the 11th Circuit Court of Appeals vacated a 2024 decision by U.S. District Judge Kathryn Kimball Mizelle of the Middle District of Florida. Appeals Court Judges Elizabeth Branch and Robert Luck found that Mizelle used "fictional" reasoning to dismiss a lawsuit brought by a Medicare whistleblower, according to the court's ruling.

Branch and Luck were both appointed by Trump, as was Mizelle, whom they overruled. Judge Federico Moreno, a George H.W. Bush appointee, joined them in the unanimous ruling.

The lawsuit revived by Branch and Luck was filed by Clarissa Zafirov, a physician who accused her employer and a group of Medicare Advantage insurers of submitting false diagnosis codes to inflate their federal payments, according to the ruling. Zafirov brought the case under the False Claims Act's qui tam provisions, which allow private citizens, or "relators," to pursue fraud claims on the government's behalf, according to the court ruling.

That structure matters because qui tam suits remain an important tool in federal fraud enforcement, especially in healthcare cases where billing practices can be complex and the government may rely on insiders to surface alleged misconduct. The appellate panel's ruling keeps Zafirov's claims alive and leaves the merits of the Medicare coding allegations for further proceedings.

Mizelle had dismissed the case after concluding that whistleblowers like Zafirov are unappointed "officers of the United States" who exercise executive power reserved by the Constitution for presidential appointees. The appeals court rejected that view.

"We disagree and hold that relators are not officers of the United States because they do not occupy a continuing position established by law," Branch wrote in the court's ruling.

Branch was especially critical of Mizelle's central theory, which held that the law created a standing "office of relator."

"There is no 'office of relator,'" Branch wrote. "That term is not in the FCA or any other law."

Branch described the "fictional 'office of relator'" as a departure "from the Supreme Court's methodology" and said a whistleblower's role is temporary and personal rather than a permanent government post. "A relator's tenure is occasional and temporary because it lasts the length of one case," Branch wrote.