John J. Gresens

Partner

Chicago, Illinois

John Gresens brings first-chair jury trial litigation experience to Taylor Duma. A registered patent lawyer, Mr. Gresens represents clients in federal courts throughout the United States and before the U.S. Patent and Trademark office. He has experience defending and asserting patent rights for both public and private companies, as well as successfully counseling his clients to avoid litigation through settlements and negotiation. With more than 35 years of legal experience, Mr. Gresens has secured hundreds of patents for his clients.

Prior to joining Taylor Duma, Mr. Gresens served as a partner in an Am Law 100 firm. He counsels both United States companies conducting international business and foreign clients seeking to do business within the United States. He helps guide clients entering new markets through patent enforcement and protection matters, as well as through licensing arrangements.

Mr. Gresens has extensive experience trying cases throughout the United States and internationally. He has first-hand knowledge of U.S. federal courts and the International Trade Commission, where he has obtained jury verdicts and exclusion orders. In addition to his litigation work, Mr. Gresens provides clients with strategic counseling and professional opinions. Beyond trying cases, he has handled inter partes review and International Contested Patent matters. He has also successfully negotiated international patent settlements for sums up to $2 billion.

Throughout his career, Mr. Gresens has gained experience in numerous industries, including chemical technology, biotechnology, material science, pharmaceuticals, nanotechnology, and material technology. In addition to his legal practice, Mr. Gresens served as an adjunct professor at Hamline University School of Law from 1990 to 2000.

Affiliations

  • American Bar Association, Intellectual Property Law Section, Member
  • Section Council, 2004 – 2008
  • American Intellectual Property Law Association, AIPLA Quarterly Journal, Editorial Board, Member, 2001 – 2004
  • Art Institute of Chicago, Lifetime Member
  • Catholic Charities of the Archdiocese of Chicago, Board of Directors
  • Chicago Public Library Foundation, Board of Directors, 2008 – 2018
  • Fire Fighter/EMT (Retired)
  • Minnesota Intellectual Property Law Association, President, 2004 – 2005
  • Minnesota State Bar Association, Member 1988 – 2019, Board of Governors, 2000 – 2006

Education

  • Hamline University School of Law, J.D., Dean’s List, 1986
  • St. John’s University, B.S. in Chemistry, 1981

Bar Admissions

  • Illinois
  • U.S. Patent and Trademark Office

news

Taylor Duma LLP Partners Alan David Barson and Barbara J. Riesberg Named to the Miami-Dade Bar’s 2025 Circle of Excellence

October 9th, 2025

Miami, Florida (October 9, 2025) — Taylor Duma LLP announced today that partners Alan David Barson and Barbara J. Riesberg have been…

Read More
insights

Practical COVID-19 Vaccine Coverage in the Midst of Regulatory Confusion

September 30th, 2025

Ongoing developments regarding COVID-19 vaccine coverage are causing employers who sponsor group health plans to grapple with shifting…

Read More
insights

Many New Tariffs Overturned on Appeal; SCOTUS Review Likely Next

September 2nd, 2025

In late August, a federal appeals court rejected the wide-ranging emergency tariffs implemented by the White House in April and August. …

Read More
insights

Airline Tickets and AI: A Cautionary Tale about Automated Pricing Practices

August 26th, 2025

The business news pages have run several stories in the last month about a group of US senators demanding answers from Delta Airlines…

Read More