Daniel Zeilberger is Of Counsel in the Litigation practice of Paul Hastings and is based in the firm’s Washington, D.C. office.

Mr. Zeilberger’s practice focuses on intellectual property matters, including patent office proceedings, district court litigation, and appeals to the Court of Appeals for the Federal Circuit. Mr. Zeilberger has substantial experience preparing written submissions; taking and defending fact witness and expert depositions; and first- and second-chairing oral arguments.

Mr. Zeilberger has handled matters involving a wide range of technical areas, including Internet-related technologies, mobile devices, semiconductor devices, telecommunications, business methods, medical devices, and pharmaceuticals. Prior to entering private practice, Mr. Zeilberger served as a patent examiner at the USPTO, where he gained valuable experience with USPTO standards and procedures.

Mr. Zeilberger devotes a portion of his time to serving the bar.  He has been actively involved in the PTAB Bar Association for several years, and currently serves on its Board of Directors. Mr. Zeilberger also works on a variety of pro bono matters, and has successfully represented several individuals seeking asylum.


  • Elected to PTAB Bar Association Board of Directors for three-year term (2021–present).
  • Recipient of the Paul Hastings Client Service Excellence Award in 2018.
  • Recognized as Legal Lion by Law360 in 2018 and 2019.


  • Georgetown University Law Center, J.D., cum laude, 2013
  • Johns Hopkins University, B.S., Electrical Engineering, with honors, 2007


  • Avery Dennison RFID Co. v. EVRYTHNG Ltd. (S.D.N.Y. & D. Mass.).  Represented EVRYTHNG in litigation involving Internet of Things (IoT) technology.
  • Chevron Oronite Company v. Infineum USA L.P. (PTAB). Represented Oronite in multiple IPRs.
  • Coalition for Affordable Drugs (ADROCA) LLC v. Acorda Therapeutics, Inc. (PTAB). Represented Acorda in multiple IPRs.
  • CoreLogic, Inc. v. Boundary Solutions Inc. (PTAB). Represented CoreLogic in multiple IPRs.
  • Factual Inc. v. Locata LBS LLC (PTAB). Represented Factual in an IPR.
  • FedEx Corp. v. IpVenture, Inc. (PTAB). Represented FedEx in an IPR.
  • Google LLC et al. v. Conversant Wireless Licensing SARL (PTAB). Represented Google in multiple IPRs.
  • Google LLC v. Flypsi, Inc. (PTAB).  Representing Google in multiple IPRs.
  • Google Inc. v. IXI Mobile (R&D) Ltd. (PTAB). Represented Google in an IPR.
  • Google LLC v. SEVEN Networks, LLC (PTAB)Represented Google in multiple IPRs.
  • Google Inc. v. Silver State Intellectual Technologies, Inc. (PTAB). Represented Google in multiple IPRs.
  • Google LLC v. IPA Technologies Inc. (PTAB). Representing Google in multiple IPRs.
  • Google LLC v. Virentem Ventures LLC (PTAB). Represented Google in multiple IPRs.
  • Infineum USA L.P. v. Chevron Oronite Company (D. Del). Represented Oronite in patent litigation involving lubricating oil technology.
  • Liqwd, Inc. v. L’Oreal USA, Inc. (D. Del.). Represented L’Oreal USA in patent litigation involving hair products.
  • Near Earth Autonomy, Inc. v. Aurora Flight Sciences Corp. (PTAB). Represented Aurora Flight Sciences in an IPR.
  • nVidia Corp. v. Samsung Electronics Co., Ltd. (PTAB). Represented Samsung in multiple IPRs.
  • SNF SA v. Chevron USA Inc(PTAB). Representing Chevron USA in IPR.

Engagement & Publications

  • Speaker, "Effective Use of an Expert in a PTAB Trial," PTAB Bar Association Annual Conference, Mar. 10, 2023.
  • Moderator, "Appeals from the PTAB," PTAB Bar Association Annual Conference, Sept. 23, 2021.
  • Coauthor, "Federal Circuit Rules PTAB APJs Violate Appointments Clause," Lexology, Nov. 1, 2019.
  • Coauthor, "A Divided Supreme Court Upholds Inter Partes Review’s Constitutionality but Constrains the Patent Office's Authority," Lexology, Apr. 25, 2018.
  • Coauthor, "The APA in PTAB Proceedings:  Notice and an Opportunity to Be Heard," Landslide® magazine, Volume 10, Issue 3, Jan./Feb. 2018.
  • Coauthor, "PTAB Section 315(b) Time-Bar Determinations Reviewable at the Federal Circuit," Lexology, Jan. 10, 2018.
  • Coauthor, "No Article III Standing Requirement for Appellees in Appeals from IPR Proceedings," Lexology, Aug. 8, 2017.
  • Coauthor, "Prosecution History Disclaimer Extends to IPR Proceedings," Lexology, May 16, 2017.
  • Coauthor, "PTAB Upholds Acorda’s Ampyra® Patents, Rejecting Challenges Based on Inventors’ Own Work," Lexology, Mar. 15, 2017.
  • Coauthor, "Give Your PTAB Record the Nutrition It Needs to Fight for You: Techniques for Discovery and Success Before the PTAB and the Federal Circuit," AIPLA Mid-Winter Institute, Feb. 3, 2017.
  • Speaker, "Recent Developments in Post Grant Proceedings at the Patent Trial and Appeal Board," IP Strategy Innovation Summit, Boston, MA, Sept. 28, 2016.
  • Coauthor, "Use of PTAB Decisions in District Court Litigation," IP Watchdog, Sept. 19, 2016.
  • Coauthor, "Five Years In:  The AIA’s Effects on Patent Litigation," Bloomberg Law, Sept. 8, 2016.
  • Coauthor, "Some Federal Circuit Guidance on Procedural Safeguards for PTAB," Law360, June 30, 2016.
  • Coauthor, "Federal Circuit Provides Guidance on the APA’s Procedural Safeguards for PTAB Proceedings," Lexology, June 16, 2016.
  • Coauthor, "PTAB Provides Guidance on AIA Estoppel Provisions," Managing Intellectual Property, Oct. 28 2015.
  • Coauthor, "Quick Fixes Implemented, New Rules on the Way for PTAB Trial Practice," Lexology, Apr. 1, 2015.
  • Coauthor for various case summaries for Federal Circuit Bar Association Circuit Case Digest.


  • PTAB Bar Association: Director on Board of Directors (2021–present); Chair of Annual Conference Committee (2019–2021); Vice-Chair of Annual Conference Committee (2018–2019).

Practice Areas


Patent Office

Patent Litigation

Intellectual Property





District of Columbia Bar

Virginia Bar

United States Patent & Trademark Office


Georgetown University Law Center, J.D. 2013

Johns Hopkins University, B.S.E.E. 2007

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