Zachary D. Caplan

Biography

Zachary Caplan represents plaintiffs in complex antitrust and other high-stakes litigation across the United States. He has investigated, briefed, and litigated antitrust cases at every stage, from the development of new claims through dispositive motions, evidentiary hearings, and trial.

Federal courts have appointed Zach to lead major antitrust class actions. He serves as Interim Co-Lead Class Counsel in In re MultiPlan Health Insurance Provider Litigation, MDL No. 3121 (N.D. Ill.), representing healthcare providers who allege that MultiPlan and major insurers colluded to suppress out-of-network payments; the court denied the defendants’ motions to dismiss in 2025, and the case is now in discovery. Zach also serves as Interim Co-Lead Class Counsel in In re Construction Equipment Rental Antitrust Litigation, MDL No. 3152 (N.D. Ill.), representing small businesses who allege that major equipment rental companies used the Rouse data platform to share competitively sensitive information and inflate prices.

Zach’s experience spans many of the most significant antitrust matters of the past decade, and he has done the hands-on work that complex cases turn on, including arguing motions, drafting dispositive briefing, taking and defending depositions, and running the case teams behind contested hearings and trial. In Castro v. Sanofi Pasteur Inc., No. 2:11-cv-07178 (D.N.J.), he was a key member of the team that challenged Sanofi’s monopolization of pediatric vaccine markets through exclusionary bundling, and he ran operations through the multi-day class certification and Daubert hearings. The court certified a class of more than 26,000 vaccine purchasers, rejected Sanofi’s challenge to the plaintiffs’ experts, and the case settled for $61.5 million. Judge Madeline Cox Arleo praised Zach and his team from the bench: “I don’t see lawyering like this every day in the federal courts, and I am very grateful.” In In re Generic Pharmaceuticals Pricing Antitrust Litigation, MDL No. 2724 (E.D. Pa.), one of the largest price-fixing MDLs in the country, Zach represented direct purchasers, for whom settlements have exceeded $465 million, and was a key drafter of dispositive briefing. He was also a member of the trial team in Ross v. American Express Co., No. 1:04-cv-05723 (S.D.N.Y.) ($49.5 million settlement), which involved a conspiracy among major Wall Street banks; in a six-week bench trial before Judge William H. Pauley III, Zach prepared witness examinations and briefed motions during trial.

Beyond monopolization and price-fixing, Zach litigates additional antitrust theories of harm. He has prosecuted reverse-payment and patent-fraud cases, including In re Loestrin 24 Fe Antitrust Litigation, MDL No. 2472 (D.R.I.) ($120 million in settlements) and In re Celebrex Antitrust Litigation, No. 14-cv-361 (E.D. Va.) ($94 million), as well as benchmark-manipulation litigation under the Sherman Act and Commodity Exchange Act. In In re Commodity Exchange, Inc. Gold Futures & Options Trading Litigation, MDL No. 2548 (S.D.N.Y.) ($152 million in settlements), Zach took and defended numerous depositions, argued discovery motions before the court, and drafted dispositive briefing. In the related In re Platinum and Palladium Antitrust Litigation, No. 14-cv-09391 (S.D.N.Y.) ($20 million settlement), he served as a principal drafter of the appellate briefing that persuaded the U.S. Court of Appeals for the Second Circuit to revive the case in 2023 after its dismissal, establishing that the exchange-trader plaintiffs were the most efficient enforcers of the antitrust laws. Zach has also repeatedly argued before the Judicial Panel on Multidistrict Litigation on the consolidation of complex antitrust cases.

Before returning to private practice, Zach served as a trial attorney with the U.S. Department of Justice’s Antitrust Division, where he led teams investigating anticompetitive conduct in healthcare and consumer products, worked on monopolization matters, and served on the Division-wide Discovery and Technology Working Group. That government enforcement experience informs how Zach investigates, structures, and prosecutes cases for his clients today.

Zach is active in the American Antitrust Institute (AAI) and the Committee to Support the Antitrust Laws, and serves on the selection committee for the AAI’s Jerry S. Cohen Award for Antitrust Scholarship. He writes and speaks frequently on antitrust law.