Kenneth H. Sonnenfeld, Ph.D.

Partner He / Him / His
New York

Dr. Sonnenfeld is a patent attorney with over 30 years of experience as intellectual property counsel to biotechnology and pharmaceutical industry clients ranging from domestic startups to multinational corporations and research institutions.

Dr. Sonnenfeld uses his technical background in pharmacology to advise on the complex technical issues that arise in biotech and pharmaceutical patent and trade secret matters. Dr. Sonnenfeld counsels clients on a range of inter-party issues, including due diligence, litigation, foreign oppositions, and licensing. He supervises complex, strategic patent prosecution before the U.S. Patent and Trademark Office and oversees foreign prosecution. Dr. Sonnenfeld has provided counsel on diligence matters aggregating in value to several billion dollars.


Representative Matters

  • National Genetics Institute and Baxter International, Inc. v. Talecris Biotherapeutics, Inc. (represented Baxter in case involving pooling of blood/plasma donations; after successful reexamination of asserted claims in USPTO, the case settled.)
  • Daiichi Sankyo Company, Ltd. v. Michelle K. Lee, Director, United States Patent and Trademark Office (represented Daiichi Sankyo in matter seeking correction of patent term)
  • Genentech vs. Novo Nordisk (defended Novo Nordisk in action involving recombinant expression of human growth hormone)
  • Conducted IP diligence and negotiated IP aspects of transaction agreements for acquisition of multiple royalty streams ranging in value up to several hundreds of millions of dollars
  • Served as Hatch-Waxman litigation counsel to Alfa Wassermann (now Alfasigma), working in conjunction with trial counsel from another firm asserting patents protecting Xifaxin® against Actavis (Teva)

Professional Highlights

Recognition & Accomplishments

LMG Life Sciences – Star, General Patent Litigation, Patent Strategy & Management (2019-2023); “Patent Strategy Attorney of the Year - New York,” Shortlist (2022, 2023) 

IAM Patent 1000 Guide, top patent lawyer (2012-2023)

IAM Global Leaders (2022-2024)

Chambers USA, Intellectual Property: Patent (2016-2023)

Managing Intellectual Property, IP Star (2018-2023)

Legal 500, Intellectual Property: Patent Prosecution – utility and design patents (2015)

Speaking Engagements

Speaker, “Digging Into the Weeds of the Supreme Court’s Funk Brothers Case to Dig out of 101 Ineligibility,” New Jersey Intellectual Property Law Association, April 30, 2019

Speaker, “Navigating Hurdles of Patentability: Subject Matter Eligibility Under the USPTO December 16, 2014 Guidance” Center for International Legal Studies: The Protection of Intellectual Property Rights, January 25-30, 2015, Kitzbuhel, Austria

Invited speaker, USPTO 101 Forum, May 9, 2014

Speaker, “Bilski and its Impact on Life Sciences Diagnostic Patents,” Center for International Legal Studies: Global IP Strategies after the Crises, February 3, 2011, Kitzbuhel, Austria.

Speaker, “Future of Medicine Conference 2009 - Open Source Panel,” participant on panel discussion to discuss issues of open source in biotechnology held at MaRS Discovery District, Canada.

Board Memberships & Community Service

Brain & Behavior Research Foundation

Fordham Law School Neuroscience Law Center


Co-author, “Bilski and Beyond: The Impact of the Bilski Decision for Biotech” BioWorld. July 22, 2010.

Author, “US Biotech Patent Law - Shifting Sands.” Life Sciences Law & Business, Issue 5, page 12, December 2004/January 2005.

Author, “US Courts Get Tough On Research Patents.” Scrip Magazine, Issue 132, page 29, March 2004.

Author, “Nerve Growth Factor Receptors on Dissociated Neurofibroma Schwann-like Cells,” Journal of Cancer Research, March 1986



Fordham University School of Law (J.D. 1990)

Columbia University (Ph.D., pharmacology, 1983)

Columbia University (M.Phil., 1979)

Columbia University (M.A., 1978)

Kenyon College (B.A., 1976)


New York


U.S. Patent and Trademark Office

U.S. Court of Appeals for the Federal Circuit

U.S. Supreme Court

U.S. District Court for the Eastern District of New York

U.S. District Court for the Southern District of New York