Jillian Thornton Flax


Jillian focuses her practice on product liability litigation and product regulatory compliance. She represents clients in the home safety product, medical device, pharmaceutical, cosmetic, highway safety product, consumer good, and retail industries. She serves as national coordinating and trial counsel for a home safety product manufacturer and highway safety product manufacturer in product liability matters throughout the United States. Jillian possesses considerable knowledge in cases involving manufacturing, design defect, and inadequate warning claims. She has significant experience litigating cases in the federal and state courts throughout the United States, where she has achieved results ranging from full defense verdicts to summary judgment dismissals on behalf of her clients.

Given her years defending clients in product liability disputes, Jillian is particularly adept at helping regulated manufacturers and distributors proactively reduce and manage their business, product liability, and regulatory compliance risk. She actively counsels clients on product development, regulatory approval, labeling, good manufacturing practices and procedures, and a wide range of matters across the regulated product life cycle.

In addition, Jillian has represented private companies, public companies, and individuals, including banks, insurance companies, and health services providers, in complex commercial litigation cases.

Based on Jillian’s trial skills, she was selected to serve as an assistant district attorney as part of the Cozen O'Connor Partners Program. In this role, Jillian worked as prosecutor in the Philadelphia District Attorney’s Office, effectively handling hundreds of criminal trials and preliminary hearings.

Jillian devotes a substantial amount of time toward pro bono cases. She recently represented a juvenile defendant previously sentenced to life without the possibility of parole in obtaining a new, constitutional sentence. 

Jillian earned her law degree from Harvard Law School and her undergraduate degree, summa cum laude, from the University of Pittsburgh.



42 Cozen O'Connor Attorneys Named Pennsylvania Super Lawyers & Rising Stars

May 24, 2023

Super Lawyers has selected 42 Cozen O'Connor attorneys to the 2023 Pennsylvania Super Lawyers and Rising Stars lists.

Jillian Flax Honored as a 2020 Lawyer on the Fast Track

June 10, 2020

Jillian Flax, member of Cozen O’Connor’s Commercial Litigation Department, has been recognized by The Legal Intelligencer as one of this year’s Lawyers on the Fast Track category.

Jillian Thornton Flax Named to Product Liability Advisory Council “Future Leaders”

April 24, 2019

Jillian Thornton Flax, a member in Cozen O’Connor's Commercial Litigation Department, was admitted to the Product Liability Advisory Council, Inc. (PLAC) as a part of their “Future Leaders” program.

$120M State AG Deal With GM Preludes More State Actions

October 20, 2017

Jillian Thornton Flax, a member in Cozen O'Connor's Commercial Litigation Department, was quoted in Law360's recent article, "$120M State AG Deal With GM Preludes More State Actions."

GM Faces Potential Mountain of New Claims in Ignition MDL

July 14, 2016

Jillian Thornton Flax, a member of Cozen O'Connor's Products Liability practice, discusses the new claims that GM is facing in Law360.


8th Circuit Reverses to Uphold Successor Liability Defense, Highlighting The Importance of Consistent, Clear Descriptions Of Acquisitions To Avoid the de facto Merger Exception [Products Liability Prevention & Defense Blog]

June 01, 2018

On April 5, the Court of Appeals for the Eighth Circuit wiped out a jury verdict in a products liability action and $13 million punitive damages award against a manufacturer and its wholly owned subsidiary on the basis that the parent company manufacturer could assert a successor liability defense....

FDA releases draft guidance on expansion of abbreviated 510(k) Program [Products Liability Prevention & Defense Blog]

May 01, 2018

On April 12, the FDA released draft guidance discussing an expansion of its Abbreviated 510(k) program for medical devices. This new guidance would allow a submitter to establish substantial equivalence by demonstrating that a new medical device meets certain performance criteria, rather than by...

Proposed Legislation to Relax Rules on Medical Device Reporting Passes U.S. House [Products Liability Prevention & Defense Blog]

July 17, 2017

On July 13, 2017, the U.S. House of Representatives passed a bill that would triple the amount of time in which medical device manufacturers are required to report certain malfunctions of some products to the Food and Drug Administration.  Companies currently must report product malfunctions within...

The Harbor Might Not Be Safe: Failure To Update Generic Drug Labels Can Invite a Storm of State-Law Claims [Products Liability Prevention & Defense Blog]

August 30, 2016

The New Jersey Supreme Court ruled on August 22 that consumers’ state-law claims that manufacturers of a generic Reglan, a heartburn medication, did not adequately warn about its risks are not preempted by federal law.[1] Under the Federal Food, Drug, and Cosmetic Act, manufacturers of brand-name...

New FDA Draft Guidance on Benefit-Risk Factors Affecting Medical Device Compliance, and Enforcement [Products Liability Alert]

August 08, 2016

Abby Sacunas and Jillian Flax discuss the U.S. Food and Drug Administration recently released draft guidance to clarify the benefit and risk factors it may consider in compliance and enforcement actions involving medical devices.


  • Harvard Law School, J.D., 2008
  • University of Pittsburgh, B.S., summa cum laude, 2005

Awards & Honors

Pennsylvania Super Lawyers "Rising Star" 2023

Lawyer on the Fast Track, The Legal Intelligencer, 2020

JD Supra’s Readers’ Choice Award Top Authors Medical Device Industry 2017

BillyPenn.com “Who’s Next in the Law: 18 young leaders making a difference in Philly’s legal community”


  • Pennsylvania
  • U.S. District Court -- Eastern District of Pennsylvania

Legal Clinic for the Disabled, former board member

Pennsylvania Bar Association Commission on Women in the Profession

Product Liability Advisory Counsel