By Sara Mieczkowski and Eddie Suarez / www:SuarezLawFirm.com
On December 12, 2025, the Eleventh Circuit heard oral arguments in a case that could reshape False Claims Act enforcement for decades. At stake in United States ex rel. Zafirov v. Florida Medical Associates is nothing less than the constitutional foundation of the qui tam mechanism that drives most FCA litigation.
The Constitutional Question
Judge Kathryn Kimball Mizelle’s September 2024 decision made legal history. She became the first federal judge to hold that the FCA’s qui tam provisions violate Article II of the Constitution. Her reasoning: when private citizens file FCA suits in the government’s name, they exercise executive power without proper appointment, a violation of the Appointments Clause.
This isn’t an abstract academic debate. The FCA’s qui tam provisions generated $2.4 billion in recoveries in fiscal year 2024 alone. Private whistleblowers filed a record 979 new cases that year. If Zafirov’s reasoning prevails, that entire enforcement framework crumbles.
What Happened at Oral Argument
The three-judge panel asked probing questions of all sides, testing the competing theories against constitutional text and practical realities.
Judge Elizabeth Branch cut to the chase early. She noted that several Supreme Court justices have recently signaled their willingness to reconsider qui tam constitutionality, a development the government’s attorney couldn’t ignore. Justice Clarence Thomas’s 2023 dissent in Polansky questioned whether the Constitution permits private parties to prosecute claims on the government’s behalf. Justice Brett Kavanaugh’s February 2025 concurrence in Wisconsin Bell signaled that the Court should consider the competing arguments on the Article II issue in an appropriate case.
The government argued that qui tam actions have deep historical roots, tracing back to 13th-century England. The First Congress passed several qui tam statutes, suggesting the Founders saw no constitutional problem with the mechanism. The defense countered that historical practice cannot override clear constitutional text and that modern FCA relators exercise far more power than their historical predecessors.
The Defense Implications
For defense practitioners, Zafirov creates both opportunity and uncertainty.
The opportunity: If the Eleventh Circuit affirms Judge Mizelle’s ruling, defendants gain a powerful new weapon. Constitutional challenges could lead to dismissal of declined qui tam cases throughout the circuit and potentially nationwide if the Supreme Court takes up the question.
Even before a final ruling, Zafirov is already reshaping litigation strategy. Defendants are invoking the constitutional arguments to limit relator participation in intervened cases, arguing that even when DOJ takes the lead, the relator’s continued role raises Article II problems.
The uncertainty: No one knows how the Eleventh Circuit will rule, or how quickly. A ruling affirming Mizelle would almost certainly draw a Supreme Court petition. A reversal would quiet the constitutional debate, at least temporarily, though other circuits may reach different conclusions.
What’s Next
The Eleventh Circuit will issue its decision in the coming months. Meanwhile, the Third Circuit will consider similar issues in the Janssen Products appeal involving a $1.6 billion FCA judgment. The Sixth Circuit may also weigh in, after a district court certified an interlocutory appeal on the constitutional question.
Defense counsel should preserve constitutional arguments in all FCA cases. Even if the Eleventh Circuit reverses, the Supreme Court’s interest in these questions makes eventual review likely. The justices have given defendants a roadmap; prudent practitioners will follow it.
For now, we watch and wait. But make no mistake: the outcome of Zafirov will shape FCA defense strategy for years to come.
