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William Joseph Mostyn IV

Intellectual property Attorney at Virtual, MA

5.0   2 reviews
  • Licensed for 13 years
    State MA
    Acquired 2010
    Active No misconduct found

We have not found any instances of professional misconduct for this lawyer.

About William

Learn William’s areas of practice.

Practice areas
  1. Intellectual property
    Patents, Trademarks, Copyrights, Trade Secrets and Domain Names

    14 years, 5 cases

  2. Litigation
    Consulting - case assessment and strategy, discovery advice, management of outside counsel

William J. Mostyn is a Registered Patent Attorney with over 18 years of experience in the technology industry.  Prior to founding Mostyn IP, he was an Associate at Cesari and McKenna LLP, a Boston-based intellectual property law firm.

Mr. Mostyn has successfully prosecuted patents for individuals and large international corporations.  His broad technological experience includes chemical, electrical and mechanical technologies, such as medical and dental devices, spectroscopy, small molecules, ion selective electrodes and wastewater treatment.  He has also successfully represented clients in federal district, state district and state appellate courts.

Prior to practicing law, Attorney Mostyn was a Clinical Research Coordinator at Boston Medical Center Hospital, a Research and Development Chemist at a small biotech company in Massachusetts, and an intern at the world-renowned Department of Biochemistry at University College Cork in Cork, Ireland, where he investigated the role of caspase-9 in cell apoptosis.  

Mr. Mostyn studied biochemistry as an undergraduate student and biochemistry, immunology, endocrinology, physiology and histology as a graduate student.

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Mostyn IP, LLC
Virtual, MA

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5.0 / 5.0
  2 customer reviews
5 Star
4 Star
3 Star
2 Star
1 Star
Posted by anonymous | February 7, 2019
This review is from a person who hired this attorney.
| Hired Attorney
One of the best lawyers we've used. Efficient, smart and of the highest integrity - something that's hard to find nowadays. Bill helped us put together a strategy to protect our IP and avoid a number of possible legal pitfalls that we hadn't considered. Bill also helped us resolve a trademark dispute in our favor. I would highly recommend him.
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Posted by Tony | August 20, 2015
This review is from a person who hired this attorney.
| Hired Attorney
Very helpful
We worked with Bill obtaining a patent. He was terrific. Bill knows patent law, is very knowledgeable of the inner workings of the patent process and was extremely helpful in the formulation of the application, suggesting innovative alternative approaches to its filing in order to enhance the possibility of its success. Bill always quickly responds to his client's questions and needs. I hope we can work with him again. Best yet, he is just a nice guy to work with and easy to talk with!
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  • Free Consultation 30 minutes
  • Hourly Rates $ 200-300 per hour
Payment methods
Cash, Check, Credit Card


AVVO RATING 8.3 (Excellent)

Work Experience

  • Founder
  • Mostyn IP, LLC
  • 2016 - Present
  • Associate
  • Cesari and McKenna LLP
  • 2011 - 2016
  • Outside Counsel
  • Genzyme Corporation
  • 2011 - 2011
  • Research Coordinator
  • Boston Medical Center Hospital
  • 2005 - 2006
  • R&D Associate
  • Cytosol Laboratories Inc.
  • 2003 - 2004
View all work experience


  • Northeastern University School of Law
  • JD - Juris Doctor
  • 2010
  • Boston University School of Medicine
  • MA - Masters
  • 2006
  • Ohio Wesleyan University
  • BA - Bachelor of Arts
  • 2003

Sample of Legal Cases

  • Savant Systems, LLC v. Crestron Electronics, Inc. (D. Mass.)
  • Positive
  • Crestron Elecs., Inc. v. Cyber Sound & Security, Inc. (D.N.J.)
  • Positive
  • Lee Valley Tools, LTD. et al. v. Industrial Blade Company (W.D.N.Y.)
  • Positive
View all legal cases


  • Boston Patent Law Association
  • 2011 - Present
  • Boston Bar Association
  • 2010 - Present

Languages Spoken

  • English

Honors and Awards

  • Rising Star
  • Super Lawyers
  • 2018
  • Rising Star
  • SuperLawyers
  • 2017


  • The American Journal of Obstetrics and Gynecology
  • 2006

Attorney endorsements

Received (1)
Given (1)
Endorse William
Intellectual property Attorney | Aug 17
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Intellectual property
Virtual Intellectual property Lawyer William Joseph Mostyn IV
William Joseph Mostyn IV
Intellectual property Attorney
Virtual, MA
Licensed for 13 years
Free Consultation