Patrick Brennan is a member of the firm’s Intellectual Property practice group counseling clients, from Fortune 500 companies to universities and startups. He regularly meets with in-house counsel, engineering and design teams to guide clients through patent preparation, prosecution and enforcement of U.S. and foreign patents, most often in the mechanical arts.

In one significant area of his practice, Patrick counsels clients on clearance and right-to-use analysis, and performs risk assessments for clients. Patrick has extensive experience in a wide range of personal care products, absorbent products, baby care and nursing products, recreational products, processing and manufacturing equipment, pest control devices and medical devices.

Patrick also represents a number of prestigious universities across the country and works closely with their research teams in various disciplines to patent cutting-edge technologies.

Registered to practice before the U.S. Patent and Trademark Office, Patrick also defends clients' patents and challenges competitors' patents at the U.S. Patent and Trademark Office in ex parte reexamination proceedings as well as inter partes review proceedings. He has successfully defended his clients in matters before the U.S. Court of Appeals for the Federal Circuit. In addition, Patrick advises clients concerning freedom-to-operate and provides recommendations for progressing or alternatives to mitigate client risk.


  • Saint Louis University School of Law  (J.D., 2002)
    • Academic Achievement Awards (Civil and Family Law)
  • University of Missouri-Rolla  (B.S., 1993)
    • Geological Engineering


  • Missouri, 2003
  • U.S. Patent and Trademark Office
  • U.S. Court of Appeals, Federal Circuit

Professional Activities

  • The Missouri Bar


  • Named among the "Best Patent Attorneys," St. Louis Small Business Monthly (2019)


Prior to law school, Patrick was an environmental engineer for an international engineering consulting firm. As a former registered professional geologist and professional engineer, he assisted clients in remediating groundwater and soil contamination, as well as reporting to state and federal regulatory agencies.