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

Kaspar Stoffelmayr is a litigator and trial lawyer at Bartlit Beck in Chicago. He has extensive background in mass tort, product liability, and class action defense, as well as in prosecuting and defending commercial disputes. In addition to successful courtroom advocacy, his experience includes the development of creative litigation and resolution strategies, the efficient management of large teams in mass litigations, and working with clients to address the public relations, regulatory, marketplace, and other issues that can arise in connection with a major litigation.

From 2011 to 2014, Kaspar took a leave of absence from the firm to serve as Vice President and Associate General Counsel at Bayer Corporation, where he was the head of litigation, managing the function that handled major U.S. litigation matters of Bayer Group companies, including Bayer HealthCare, Bayer MaterialScience, and Bayer CropScience. In that capacity, he had overall responsibility for developing and implementing the company's defense strategies for a large docket of product liability and mass tort cases, class actions, and a variety of other matters.

Kaspar graduated from The University of Chicago Law School with High Honors in 1996 and clerked for Judge A. Raymond Randolph on the U.S. Court of Appeals for the D.C. Circuit. He received a B.A. with Honors from Grinnell College and an M.A. from the University of Washington. He joined Bartlit Beck in 2000 and became a partner in 2003

Kaspar is a frequent speaker on complex litigation, mass torts, product liability, and class actions. He has testified before the Judicial Conference Advisory Committee on Rules of Civil Procedure for the federal courts and the House Judiciary Committee (Subcommittee on Courts, Intellectual Property, and the Internet).

Representative Matters

Opioids Litigation
Lead counsel and trial counsel for Walgreens in nationwide litigation relating to the distribution and sale of prescription opioid medications, including over 2,500 cases brought by states, cities, counties, tribes, and private parties seeking recovery in connection with the opioid abuse crisis. MDL in the Northern District of Ohio and a large number of related cases pending in other state and federal courts. Liaison counsel for all 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 another large pharmaceutical manufacturer. Case won.

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. MDL in the Southern District of Illinois and large coordinated state-court proceedings in California, New Jersey, and Pennsylvania. No adverse judgments among approximately 20,000 lawsuits and claims resolved on motions to dismiss or summary judgment, voluntary dismissals, and settlements.

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

Confidential Telecommunications Arbitration
Lead counsel and trial counsel for a major cable company in the confidential arbitration of a contract dispute with an internet technology vendor. Case won.

Combination Aspirin Products Litigation
National counsel for Bayer in multidistrict class action litigation involving sales of combination aspirin products. MDL in the Eastern District of New York. Litigation settled.

Bayer HealthCare v. Abbott
Bayer HealthCare v. Centocor Ortho Biotech
Represented Bayer in patent litigation in the District of Massachusetts relating to human anti-TNF alpha antibodies, Abbott's Humira medication, and Centocor's Simponi medication. Cases settled.

Teflon Product Liability Litigation
National counsel for DuPont in an MDL in the Southern District of Iowa including numerous purported class actions brought by consumers who purchased cookware made with Teflon non-stick coatings. Cases dismissed.

Factor VIII and IX Blood Products Litigation
National counsel for Bayer in worldwide product liability litigation alleging infection with HIV and hepatitis C from plasma derivatives used to treat hemophilia. MDL in the Northern District of Illinois and counterpart litigation in multiple foreign countries. Cases dismissed or settled.

PPC v. Arris International
Trial counsel for Arris in patent litigation in Colorado and Wisconsin regarding coaxial cable connectors. Jury trial in Madison, Wisconsin. Cases settled following a jury verdict for PPC on some issues and the grant of a new trial to Arris on others.

C&W Fabricators v. Meriwether Capital
Trial counsel for the buyers of a business in an arbitration against the sellers regarding indemnification for warranty obligations. Case won.

People v. Filliung
Trial counsel in the first-degree murder trial in Cook County, Illinois, of a defendant with a history of mental illness. Obtained a verdict of not guilty.

SWANCC v. U.S. Army Corps of Engineers
Represented the Solid Waste Agency of Northern Cook County in a United States Supreme Court challenge to the scope of the Clean Water Act. Judgment reversed.

Neder v. United States
Represented a criminal defendant challenging his convictions on fraud and RICO charges in the United States Supreme Court. Judgment reversed in part.

Education & Honors

The University of Chicago Law School, 1996, J.D., with High Honors

Order of the Coif

Joseph Henry Beale Prize

Comment Editor, The University of Chicago Law Review

University of Washington, 1993, M.A.

Grinnell College, 1991, B.A., with Honors

Phi Beta Kappa


  • Honorable A. Raymond Randolph, U.S. Court of Appeals for the District of Columbia Circuit, 1996-1997

Awards & Recognition

Ranked by Chambers USA as one of the leading Product Liability & Mass Torts lawyers in the United States

Recognized in Benchmark Litigation as a Litigation Star

Lawdragon 500 Leading Litigators in America

Recognized as an Illinois Super Lawyer


  • Illinois
  • Pennsylvania
  • Colorado (inactive)
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