Gibson Dunn Expands Market-Leading Mass Torts and Product Liability Practice With Three-Partner Trial Team Led by Kimberly Branscome
Press Release | September 18, 2026
Gibson Dunn announced today that accomplished trial lawyers Kimberly Branscome, Yahonnes Cleary, and Jonathan Tam have joined the firm’s premier Mass Torts and Product Liability Practice Group as partners, with Kimberly joining as Co-Chair. The team brings significant first-chair trial experience in some of the country’s most consequential product liability and mass tort litigation, particularly in the pharmaceutical, medical device, consumer product, and industrial sectors. Kimberly and Jonathan practice in Los Angeles, and Yahonnes practices in New York.
“Kimberly, Yahonnes, and Jonathan are exceptional trial lawyers with tremendous market credibility and a proven record of success in some of the most challenging venues in the country,” said Theodore J. Boutrous Jr., a litigation partner in Gibson Dunn’s Los Angeles office. “Their lead trial lawyer experience in complex and industry-threatening commercial cases is a perfect fit for our firm history and platform and will be a significant asset to clients facing their most consequential product liability and mass tort matters in California and nationwide.”
The team has secured defense verdicts in some of the most closely watched product liability trials of the past decade for clients including Bayer, Johnson & Johnson, 3M, and Pfizer.
“We’ve worked alongside this team on major product liability litigation, so we know firsthand what they bring when the stakes are highest,” said Lauren Goldman, Co-Chair of Gibson Dunn’s Mass Torts and Product Liability Practice Group. “For clients defending major mass tort litigation, trials can shape the entire docket. They need lawyers who can set the strategy, drive the critical legal and expert issues, and persuade the jury. This team brings that rare combination. Together, we offer clients unmatched depth from strategy through trial and appeal.”
“Gibson Dunn has built an extraordinary litigation platform, with elite trial, appellate, complex litigation, and environmental capabilities and a genuinely collaborative culture,” said Kimberly. “Bringing our team onto that platform, with the many synergies across our practices, was a uniquely compelling opportunity. Product liability litigation is becoming larger, more complex, and higher stakes across jurisdictions, and clients need exceptional depth at every stage. We’re excited to help clients navigate their most consequential matters in California and nationally.”
About the Team
- Kimberly Branscome – Kimberly is a seasoned first-chair trial lawyer and litigation strategist specializing in product liability, mass torts, and complex commercial litigation. She serves as lead counsel in high-profile pharmaceutical, medical device, consumer product, and industrial litigation, including nationwide mass torts and multidistrict litigation (MDL). With degrees in biomedical and chemical engineering, Kimberly brings a deep understanding of the complex scientific and technical issues at the heart of many of these matters, including epidemiology, toxicology, product design, exposure, and causation. She has significant experience trying sensitive, business-threatening cases and also serves as national counsel in large MDLs, advising clients at all stages of litigation and crisis management. Her clients include leading companies across the life sciences, consumer products, energy, automotive, and manufacturing sectors.
- Yahonnes Cleary – Yahonnes is a complex commercial litigator with particular expertise in product liability and mass tort disputes and trial. Yahonnes’ clients include sophisticated institutions in highly regulated sectors: pharmaceutical and life sciences, energy and chemical businesses, technology and consumer data companies, financial institutions, insurers, and quasi-public organizations. In addition to product liability and mass tort, his experience includes consumer class actions, data privacy, securities litigation, regulatory matters, and internal investigations. He defends clients at all phases of litigation and trial.
- Jonathan Tam – Jonathan is a litigation strategist and trial lawyer. His practice focuses on representing companies in their most complex and high-stakes product liability litigations, mass torts, class actions, and civil actions brought by State Attorneys General. His experience includes defending companies in the largest and most complex federal MDLs in history. His clients have spanned across a variety of industries, including pharmaceutical, medical device, life science, high-tech, and other innovative companies.
About the Mass Torts and Product Liability Practice Group
Gibson Dunn’s Mass Torts and Product Liability Practice Group stands at the forefront of the most consequential litigation in the country, representing a broad spectrum of clients in their most complex, high-profile, and high-stakes matters. The team has significant capabilities across a host of disciplines and industries, and our practice is built around national strategy, dispositive legal and expert issues, trials, and appellate work — the capabilities that win the largest matters. The practice recently earned Band 1 rankings in Chambers USA nationally for both Product Liability & Mass Torts and Toxic Torts.