Barclay Damon
Barclay Damon

Denis J. Sullivan

Denis J. Sullivan


p: 315.425.2868

f: 315.703.6252

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Syracuse Office

Barclay Damon Tower
125 East Jefferson Street
Syracuse, New York 13202

Denis is a nationally recognized intellectual property lawyer and leads Barclay Damon’s Intellectual Property Group. Clients value the depth and breadth of Denis’ capabilities. As a registered patent attorney, he handles patent infringement disputes in federal district court and at the International Trade Commission, patent office proceedings such as inter partes reviews and reexaminations, and the preparation of patent applications. His experience as both a patent litigator and a patent prosecutor enables Denis to successfully challenge and defend patents under the America Invents Act before the US Patent and Trademark Office. He regularly serves as lead counsel in IPRs of patents involved in district court litigation.

Denis’ ability to provide clients with high-value intellectual property counsel is enhanced by his strong engineering background. He graduated first in his class with a bachelor’s degree in electrical engineering and worked for several years as a licensed professional engineer. This technical background enables Denis to handle patent matters in a wide variety of technologies and industries, including health care, telecommunications, semi-conductor manufacturing, and oil and gas industries.

After graduating first in his class from law school, Denis began his legal career as an intellectual property litigation associate at Kirkland & Ellis. He later joined an intellectual property boutique, where he became managing partner before joining Barclay Damon in 2011.

Representative Experience

  • Lead counsel for a patent owner in over 20 IPRs of patents involved in district court litigation. Representative proceedings where all patent claims survived without amendment include IPR2014-00440, IPR2014-00441, IPR2014-00736, IPR2015-01952, and IPR2015-01955.
  • Lead counsel for a patent owner in Federal Circuit appeals of an IPR. Obtained dismissals of appeals based on lack of jurisdiction.
  • Lead counsel for a patent owner in reexaminations of several patents involved in district court litigation. Representative proceedings where all patent claims survived without amendment include Control Nos. 90/13,068 and 90/013,069.
  • Prepare and prosecute patent applications and appeals for domestic and foreign clients, including Fortune 100 clients.
  • Lead counsel for a patent owner in patent infringement action involving software patents for electronic shareholder communications. (D. Del.) 
  • Trial counsel for a patent owner in an ITC proceeding involving patents for coaxial cable connectors. Obtained two general exclusion orders and one limited exclusion order. 
  • Trial counsel for a patent owner in declaratory judgment action involving patents for chemical de-icers, successfully defending the validity of the patents. (N.D.N.Y.) 
  • Lead patent counsel in a district court appeal of the USPTO interference proceeding. Obtained summary judgment reversing the patent office to preserve the validity of the patent. (N.D.N.Y.) 
  • Provide counseling and legal opinions concerning the validity and infringement of patents.

Practice Areas


  • New York Law School, J.D., summa cum laude (Class Rank: 1), New York Law School Law Review, 2002
  • Manhattan College, B.S., summa cum laude (Class Rank: 1), General Excellence Award in Electrical Engineering, 1993

Admitted To Practice

  • New York, 2003
  • U.S. Patent and Trademark Office
  • U.S. District Court, Northern District of New York
  • U.S. District Court, Southern District of New York
  • U.S. District Court, Eastern District of New York
  • U.S. District Court, Western District of New York
  • U.S. Court of Appeals, Federal Circuit

Memberships & Affiliations

  • Intellectual Property and Innovation American Inn of Court, Member
  • New York State Bar Association
  • American Intellectual Property Law Association
  • New York State Licensed Professional Engineer

Speaking & Publications

  • Practicing Law Institute (PLI), 11th Annual Patent Law Institute, April 2017, New York, NY, Panelist, "The Patent Trial and Appeal Board Turns Five"
  • "Strategies For Avoiding Institution Of An IPR," Law360, January 25, 2017
  • IP Counsel Exchange, December 2016, New York, NY, Panelist, “PTAB Litigation Crash Course: A Litigator’s Guide to Obtaining Successful Results at the PTAB” 
  • Rochester Intellectual Property Law Association (RIPLA), November 2015, Rochester, NY, Presenter, “Escaping from Wonderland: An Analysis of Decisions Where Patent Claims Have Survived Section 101 Challenges Under Alice Corp. v. CLS Bank.”
  • Practicing Law Institute (PLI), 9th Annual Patent Law Institute, February 2015, New York, NY, Presenter, "Inter Partes Review and Post-Grant Review - Interplay of PTAB/District Court Litigation"

Prior Experience

  • Marjama Muldoon Blasiak & Sullivan LLP, Partner
  • Kirkland & Ellis LLP, Associate
  • Port Authority of New York and New Jersey, Electrical Engineer and Project Manager

Patent Experience