Kaspar J. Stoffelmayr

"A strategic trial lawyer who can play the whole field." – Chambers USA Guide 2021

"An amazing strategist. An incredibly talented lawyer who is also easy to work with." – Chambers USA Guide 2025

"An elite trial lawyer” and “a top-notch business adviser." – Chambers USA Guide 2025

"Kaspar is a true strategic partner and a superior trial attorney."  – Chambers USA Guide 2026

Kaspar Stoffelmayr is a litigator and trial lawyer who has spent more than 25 years helping clients meet their most difficult litigation challenges, including mass torts, class actions, and complex commercial disputes. He has led these matters both as outside counsel and as a senior in-house lawyer.

Kaspar has defended mass torts involving products that range from oral contraceptives to hemophilia therapies to widely used over-the-counter drugs. His class action work spans household goods to prescription medical devices. He has litigated these matters in federal MDLs and consolidated state-court proceedings, as well as in single-plaintiff cases. He is equally comfortable as lead counsel before the court, as trial counsel in front of a jury, and as settlement counsel in negotiations.

Since 2018, Kaspar has led Walgreens’ defense in the national prescription opioid litigation, including thousands of cases brought by states, local governments, tribes, hospitals, payors, and individuals in a federal MDL and in state courts nationwide. The team that Kaspar leads has achieved victories on dispositive motions, at trial, and on appeal, plus major settlements with state attorneys general and local governments.

From 2011 to 2014, Kaspar served as head of litigation at Bayer, with overall responsibility for the company’s defense and resolution strategies across a large docket of product liability and mass tort cases, class actions, and other matters. No one appreciates a client’s perspective like a former client.

Kaspar believes that, in mass litigation, clients need lead counsel focused on the whole board, not just the next hearing, the next big motion, or even the next trial. These cases can unfold over years in front of any number of judges with very different views of the litigation. Defendants may face a diverse array of opposing parties with their own interests and incentives. The litigation often brings unique communications, regulatory, and marketplace challenges. A successful outcome can therefore involve much more than winning a particular case. As one source told Chambers USA, Kaspar is both “a true strategic partner and a superior trial attorney.”

Beyond his advocacy for clients, Kaspar is an active voice on legal reform. He is the longtime co-chair of Lawyers for Civil Justice’s MDL Committee. He has testified before Congress on civil procedure and federal jurisdiction, and before the federal Advisory Committee on Civil Rules. He speaks frequently on mass torts, product liability, complex litigation, and class actions.

Kaspar graduated with high honors from the University of Chicago Law School and clerked for Judge A. Raymond Randolph on the D.C. Circuit. He joined Bartlit Beck in 2000 and became a partner in 2003.

Representative Matters

Acetaminophen (Tylenol) Litigation
Lead counsel for a national retailer in litigation alleging a connection between acetaminophen and both autism spectrum disorder and ADHD.

Opioid Litigation
Lead counsel and trial counsel for Walgreens in nationwide litigation relating to the distribution and sale of prescription opioid medications. Liaison counsel for chain pharmacy defendants in the MDL.

Confidential Pharmaceutical Industry Arbitration
Lead counsel and trial counsel for a major pharmaceutical company in the confidential arbitration of a commercial dispute with a competitor.

YAZ/Yasmin Product Liability Litigation
Lead counsel for Bayer in nationwide product liability litigation alleging personal injuries caused by the oral contraceptives YAZ and Yasmin.

Xarelto Product Liability Litigation
Counsel for Bayer in lawsuits alleging personal injuries caused by the novel anticoagulant Xarelto.

Combination Aspirin Products Litigation
Counsel for Bayer in multidistrict class action litigation involving combination aspirin products.

Teflon Litigation
Counsel for DuPont in multidistrict class action litigation related to alleged risks associated with nonstick cookware.

Factor VIII and IX Blood Products Litigation
Counsel for defendants in worldwide product liability litigation alleging infection with HIV and hepatitis C from plasma derivatives used to treat hemophilia.

Anti-TNF Alpha Patent Litigation
Counsel for a patent holder asserting claims relating to multiple anti-TNF alpha monoclonal antibody medications.

Confidential Telecommunications Arbitration
Lead counsel and trial counsel for a leading ISP in the confidential arbitration of a contract dispute with a technology vendor.

PPC v. Arris International
Trial counsel for the defendant in a patent dispute involving coaxial cable products.

C&W Fabricators v. Meriwether Capital
Trial counsel in the arbitration of a commercial dispute over indemnification obligations.

People v. Filliung
Trial counsel for the defense in a first-degree murder trial.