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Justin J. Leisey


[email protected]



Justin is a registered patent attorney with a background in chemical engineering. He drafts and prosecutes US and foreign patent applications for clients in a variety of industries, including the life sciences, biotechnology, medtech, pharmaceuticals, energy and sustainability, cleantech, manufacturing, and technology sectors.

Justin regularly conducts patent searches and drafts invalidity/infringement and patentability opinions, assesses risks associated with freedom-to-operate issues, drafts landscape analyses and competitive intelligence reports, and identifies whitespace opportunities. His work also includes performing due diligence on third-party intellectual property, reviewing and drafting IP provisions of transactional and licensing agreements, and handling patent litigation, inter partes review, and interference matters.  

Prior to joining Mintz, Justin was an associate in the San Diego and Boston offices of an international law firm. He also worked as intellectual property counsel and as a patent agent/law clerk at Reflexite Corporation (now part of ORAFOL GmbH), a manufacturing company producing reflective materials. In addition, he taught executive-MBA class sessions on intellectual property protection at San Diego State University and maintained an active pro bono practice.

Before he earned his law degree, Justin worked as a process engineering manager and as a process engineer at Reflexite, and as a production supervisor/engineer and process engineer at Ablestik Laboratories, Inc.

He has experience working with technologies including drug delivery polymers, nutraceuticals, syringes, endoscope tube sets, laparoscopic staplers, medical devices, lithium batteries, ultracapacitors, electronic devices, engineered fuels, graphene composites, liquid-impregnated surfaces, microtrenching, polymers, polymer processing, rotary/linear actuators, basalt fibers, and variable data printing.


  • University of Connecticut (JD)
  • Virginia Polytechnic Institute & State University (BS, Chemical Engineering, cum laude)


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Understanding Chinese Voluntary Divisional Application Patent Practice

February 10, 2021 | Blog | By Andrew D. Skale, Justin J. Leisey

For many parts of the world, a voluntary divisional application (known as a continuation application in the U.S.) may be filed at any time during the pendency of any parent application.  The claims in the voluntary divisional application must be supported by the original specification and cannot introduce any new matter.  
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An Informative PTAB Decision on Patent Eligibility under 35 U.S.C. § 101

January 30, 2020 | Blog | By Christina Sperry, Justin J. Leisey

The U.S. Patent Trial and Appeal Board (“PTAB”) recently designated its decision in Ex Parte HANNUN (Appeal 2018-003323) (“HANNUN”) as being informative regarding the application of the latest 2019 revised guidance on patent-eligible subject matter. 
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Ex parte WILHELM HEINE: PTAB Rejects Examiner’s Unreasonable Claim Construction

October 7, 2019 | Blog | By Andrew D. Skale, Justin J. Leisey

During patent prosecution, Examiners often liberally apply the broadest reasonable interpretation standard in rejecting claims.  When responding to these rejections, it is important to remember that there are limits to an Examiner’s broadest reasonable interpretation. 
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Federal Circuit Closes Another AIA Loophole

June 28, 2019 | Blog | By Michael Van Loy, Justin J. Leisey

The Federal Circuit recently ruled that state sovereign immunity does not apply in Inter Partes Review (IPR) proceedings, closing another America Invents Act (AIA) loophole.  The case, Regents of the University of Minnesota v. LSI Corporation and Avago Technologies U.S. Inc. (Fed. Circ., 2018-1559), included the review of six Patent Trial and Appeal Board (PTAB) IPRs where the Regents of the University of Minnesota (UMN) filed motions to dismiss based on state sovereign immunity. 
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