Attorney Profile

Diane Fenner



Diane Fenner graduated from the University of Pennsylvania Law School, and received her Bachelor of Arts degree with honors from Barnard College. Diane also has a Ph.D. in social psychology from the Graduate School of Arts and Sciences at Columbia University, where she specialized in the intersection between law and psychology, and was involved in jury selection as well as mock jury and focus group work in various high profile cases in the 1970s, including the Kent State trial and the MCI v. AT&T litigation.

Diane has been practicing law since 1983, and has an AV rating from her colleagues, as determined by Martindale-Hubbell. After 4 years at the prestigious Philadelphia-based defense firm of Pepper Hamilton, Diane switched to a practice exclusively devoted to the representation of injured individuals. As such, she has practiced in almost all areas of personal injury, including medical malpractice, automobile accidents, premises liability, product liability, drug and medical device litigation, and workers’ compensation, and has lectured for the American Association of Justice and the Philadelphia Bar Association.

Because of her background as a Ph.D. social psychologist, Diane is particularly interested in the marketing aspects of drug and medical device litigation, as well as settlement negotiation and trial strategy issues. With respect to marketing in particular, her expertise has been put to good use, as lawyers from across the country try to understand the ways in which the drug or medical device manufacturer – sometimes subtly and sometimes not subtly – have led doctors, the FDA and/or the public astray, by the minimizing the risks of their products so as to maximize their profits. Diane was involved extensively in Hormone Therapy (Prempro), Stadol, Vioxx, Invokana and Abilify litigation, and is currently assisting in the discovery aspect of the ongoing Juul litigation.

Because of her unique background and her tenacity, in the area of workers’ compensation, Diane is often seen by clients as the lawyer who will spend hours explaining how the workers’ compensation system works and what the next part of their claim entails, and is seen by adversaries as one of the most aggressive and tenacious lawyers practicing in the workers’ compensation arena.

Because of her passion for getting at the heart of every matter she encounters in life – whether in her work life, her philanthropic life, or her personal life — as simply as possible, Diane has been successful in reducing even complex medical malpractice and product liability matters to easy-to-understand language, and this passion has been the secret of her success.

On a personal note, Diane and her husband, Dr. David Zwillenberg, have five grown children and many adored grandchildren. Diane has been practicing full time since graduating from law school, and recently moved back to Philadelphia after raising her children in the suburbs. Diane is a trained hotline volunteer for domestic violence prevention centers, and has helped countless women find a safe and secure life after experiencing domestic violence.

“Diane Fenner is the bomb lawyer always represented herself with loyalty to me. Thank God for her.”

Why Work With Diane Fenner?

Diane prides herself and has been recognized by numerous clients as taking special care to treat every client as an individual, giving them the attention she would want from them if their roles were reversed.

Areas of Practice

Dangerous Drugs, Defective Medical Devices, Personal Injury, Pharmaceutical Litigation, Product Liability, Medical Malpractice, Premises Liability, and Workers’ Compensation.

Background & Qualifications:

Below is an overview of Diane’s background and qualifications.


  • University of Pennsylvania Law School, J.D., 1983
  • Columbia University, Ph.D., Social Psychology, 1983
  • Barnard College, B.A., with honors, 1973

Bar Admissions

  • Commonwealth of Pennsylvania
  • U.S. District Court, Eastern District of Pennsylvania
  • Supreme Court of Pennsylvania

Associations & Affiliations

  • Philadelphia Bar Association
  • American Association for Justice
  • Pennsylvania Association for Justice

Community Activities

  • Kohelet Yeshiva, Board of Directors, President, 2014-2019


  • AAJ’s Litigating Tort Cases, chapter entitled “Drugs and Medical Devices”

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