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. He counsels domestic and international clients of all sizes regarding patent, trademark, and copyright law. He 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. On a part-time basis, Peter has served as in-house counsel for a Fortune 500® company, where he worked 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 counseled clients regarding intellectual property matters related to a wide variety of mechanical and electro-mechanical technologies, including:

  • propulsion devices and related control systems for marine vessels
  • engines
  • electric motors
  • mechanical and electro-mechanical tools
  • 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

From 2021-2023, 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. He has also been selected for inclusion in the 2016-2023 Thomson Reuters' Wisconsin Super Lawyers lists, and the 2014-2023 IAM Patent 1000 lists as a top patent practitioner, in which he received client accolades such as: “There is no one like [Peter Holsen] when it comes to service-mindedness, responsiveness, knowledge, and legal and technical capabilities. He can understand any invention, no matter how complicated, and apply it in a legal setting.”

Education and Engineering Experience

Peter received a B.S. in civil engineering from Marquette University and a J.D from Marquette University Law School, where he was Editor-in-Chief of the school’s Intellectual Property Law Review. He was an Evans Scholar at Marquette University, where he served on the Chapter Board. Prior to law school, Peter was a lead engineer at a multi-national engineering and consulting firm, where he designed and managed large-scale engineering projects at electrical, petrochemical, and chemical facilities.