Zimmer, Citron & Clarke

Zimmer, Citron & Clarke is a specialized appellate litigation boutique co-founded in March 2025 by David Zimmer, Eric Citron, and Edwina Clarke. With offices in Boston, Massachusetts; Washington, D.C.; and Madison, Wisconsin, the firm focuses on high-stakes appeals and complex motions practice in both federal and state courts, including the U.S. Supreme Court. The firm offers a unique model, providing sophisticated appellate advocacy and legal analysis, often in collaborative arrangements with plaintiff-side trial firms, and also offers strategic insight to investment firms and litigation funders. The firm is not listed in the AmLaw 100 or Chambers Global rankings, consistent with its boutique and recently formed nature.

The firm's IP litigation specialty includes handling patent appeals in the Federal Circuit, representing both patent owners and defendants across various technologies such as pharmaceuticals, medical devices, and computing technology. David Zimmer, a co-founder, has extensive experience in appeals and complex civil litigation, including dozens of appeals in federal and state appellate courts. Edwina Clarke, another co-founder, also brings experience in patent litigation from her previous role at Goodwin Procter.

Zimmer, Citron & Clarke demonstrates a balanced approach to patent litigation, appearing for both plaintiffs and defendants. The firm has represented Viasat, Inc. as plaintiff and Western Digital Technologies, Inc. as defendant in separate but related patent disputes concerning flash memory technology. This indicates their capability to engage on either side of a patent infringement or validity challenge.

One notable outcome involves Viasat, Inc. v. Western Digital Technologies, Inc., where the U.S. Court of Appeals for the Federal Circuit affirmed the Patent Trial and Appeal Board's (PTAB) decision that Viasat's flash memory patent claims were unpatentable for obviousness. David Zimmer was listed as counsel for Viasat in the Federal Circuit appeal, highlighting the firm's involvement in post-grant review proceedings and appellate challenges.

While the firm's primary focus is appellate litigation and complex motion practice, its involvement in the Viasat case at the Federal Circuit, which originated from an inter partes review (IPR) at the PTAB, confirms their engagement in post-grant review processes. The firm's practice description notes experience arguing or leading briefing for dozens of patent appeals in the Federal Circuit, encompassing a range of technologies. Key partners leading the firm's litigation efforts include co-founders David Zimmer, Eric Citron, and Edwina Clarke. David Zimmer is recognized in Chambers USA's Nationwide Appellate Rankings and was a Law360 Appellate Rising Star in 2021. Edwina Clarke has been named to Benchmark Litigation's "40 & Under Hot List" for multiple years and recognized by Best Lawyers in America for appellate litigation. Eric Citron has significant experience in high-stakes plaintiff-side litigation and has handled multiple cases at the U.S. Supreme Court.