Peter T. Holsen
(414) 271-7590

Practice Areas

  • Patent
  • Trademark & Copyright
  • IP Transactions
  • Client Counseling on IP

Technology Areas

  • Mechanical Patents
  • Electrical Patents & Software Patents


  • Marquette University College of Engineering (B.S. Civil Engineering)
  • Marquette University Law School (J.D.)

Bar and Court Admissions

  • United States Patent & Trademark Office
  • U.S. Court of Appeals for the Federal Circuit
  • U.S. District Courts for the Eastern and Western Districts of Wisconsin
  • Supreme Court of Wisconsin
  • U.S. Supreme Court

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Peter T. Holsen is a partner and registered patent attorney at Andrus Intellectual Property Law.

Peter counsels domestic and international clients of all sizes regarding patent, trademark and copyright law. On a part-time basis, he has served as in-house counsel for a Fortune 500® company, working closely with in-house general counsel and engineering management to formulate competitive intellectual property strategies and build a strategic patent portfolio that protects the client's core technology.

Peter has extensive experience preparing and prosecuting patent and trademark applications and drafting technology agreements. He also routinely provides clients with patentability analyses and opinions regarding patent and trademark infringement and validity.

As a registered patent attorney, Peter has worked with a wide variety of mechanical and electro-mechanical technologies, including propulsion devices and related control systems for marine vessels; engines; electric motors; fluid systems; oil and gas extraction, production and transportation systems; automated food processing equipment; automated packaging equipment; packaging materials; materials handling equipment; production machining; rail car and rail yard management technologies; robotic milking devices; medical patient imaging, monitoring and treatment technologies; water and wastewater recovery and treatment systems; and mechanical tools.

He has been selected for inclusion in Thomson Reuters' 2016-2021 Wisconsin Super Lawyers lists, and in the 2014-2021 IAM Patent 1000 lists as a top patent practitioner.

In 2021 and 2022, Peter was named a “Thomson Reuters Stand-Out Lawyer” for providing excellent legal counsel to his clients. The Thomson Reuters Standout Lawyers Program is a resource for in-house counsel which is entirely free from law firm influence.

Peter is an active volunteer and participant in The Rotary Club of Milwaukee. He is also a participant in and has been a contributing author for the International Association for the Protection of Intellectual Property (AIPPI), an international organization dedicated to the development and improvement of intellectual property. He is a member of the American Bar Association and its section of Intellectual Property Law, the American Intellectual Property Law Association, the Wisconsin Intellectual Property Law Association, and the Milwaukee Bar Association.

Peter received a Bachelor of Science in civil engineering from Marquette University and a Juris Doctor from Marquette University Law School. While attending law school, Peter was Editor-in-Chief of the Marquette University Law School Intellectual Property Law Review, for which he also authored a comment. Peter was an Evans Scholar at Marquette University, where he served on the Chapter Board. Prior to law school, Peter served as an engineer at a multi-national engineering and consulting firm where he designed and managed several large-scale engineering projects at electrical, petrochemical and chemical facilities.

Peter is admitted to practice law before the U.S. Supreme Court, the Supreme Court of Wisconsin, the U.S. District Courts for the Eastern and Western Districts of Wisconsin, and the U.S. Court of Appeals for the Federal Circuit. He is also licensed to practice before the U.S. Patent and Trademark Office.