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Overview
Daniel Zeilberger is a partner in the Litigation Department of Paul Hastings and is based in the firm’s Washington, D.C. office.
Daniel'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. Daniel has substantial experience leading teams in all aspects of IP litigation. His cases involve 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, Daniel served as a patent examiner at the USPTO, where he gained valuable experience with USPTO standards and procedures.
Accolades
- Treasurer, PTAB Bar Association (2025–Present) and Board of Directors (2021–24)
- Rising Star, Managing Intellectual Property's IP Stars (2025)
- Paul Hastings Client Service Excellence Award
- Legal Lion, Law360
Education
- Georgetown University Law Center, J.D. (cum laude) 2013
- Johns Hopkins University, B.S., Electrical Engineering (with honors) 2007
Representations
- 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 Chevron Oronite in IPR challenging patent directed to lubricating oil composition. All claims found unpatentable by PTAB and decision affirmed on appeal.
- Coalition for Affordable Drugs (ADROCA) LLC v. Acorda Therapeutics, Inc. (PTAB). Represented Acorda as patent owner in multiple IPRs. Secured denial of institution and/or affirmance of all claims at final written decision in all IPRs.
- Google LLC v. Flypsi, Inc. (PTAB). Representing Google in multiple IPRs and on appeal. Case is ongoing.
- Google Inc. v. IXI Mobile (R&D) Ltd. (PTAB). Represented Google in an IPR. Resulted in adverse judgment against the patent owner.
- Google LLC v. IPA Technologies Inc. (PTAB). Representing Google in multiple IPRs and on appeal. Case is ongoing.
- Google LLC v. Virentem Ventures LLC (PTAB). Represented Google in multiple IPRs challenging nine patents. All challenged claims found unpatentable by PTAB and decisions affirmed on appeal.
- Infineum USA L.P. v. Chevron Oronite Company (D. Del). Represented Chevron Oronite in patent litigation involving lubricating oil technology. Case terminated following invalidation of patent-at-issue.
- Johns Hopkins University v. Merck Sharp & Dohme LLC (D. Md.). Representing Merck in district court patent litigation. Case is ongoing.
- Liqwd, Inc. v. L’Oreal USA, Inc. (D. Del.). Represented L’Oreal USA in district court patent litigation involving hair products and on appeal.
- Merck Sharp & Dohme LLC v. Johns Hopkins University (PTAB). Representing Merck in multiple IPRs. Case is ongoing.
- Pilot Energy Solutions, LLC v. Chevron U.S.A. Inc. (S.D. Tex.). Represented Chevron in district court litigation.
- Samsung Electronics Co., Ltd. v. Lynk Labs, Inc. (PTAB). Representing Samsung in multiple IPRs and on appeal. Case is ongoing.
Insights
Engagement & Publications
- “Effective Use of an Expert in a PTAB Trial,” PTAB Bar Association Annual Conference, Speaker (March 10, 2023)
- “Appeals from the PTAB,” PTAB Bar Association Annual Conference, Moderator (Sept. 23, 2021)
- “Recent Developments in Post Grant Proceedings at the Patent Trial and Appeal Board,” IP Strategy Innovation Summit, Boston, MA, Speaker (Sept. 28, 2016.
- “Federal Circuit Clarifies the Scope of IPR Estoppel,” Lexology, Co-author (May 9, 2025)
- “USPTO Rescinds Memorandum Addressing Discretionary Denial Procedures,” Lexology, Co-author (March 3, 2025)
- “Federal Circuit Rules PTAB APJs Violate Appointments Clause,” Lexology, Co-author (Nov. 1, 2019)
- “A Divided Supreme Court Upholds Inter Partes Review’s Constitutionality but Constrains the Patent Office's Authority,” Lexology, Co-author (April 25, 2018)
- "The APA in PTAB Proceedings: Notice and an Opportunity to Be Heard,” Landslide® magazine, Volume 10, Issue 3, Co-author (January/February 2018)
- “PTAB Section 315(b) Time-Bar Determinations Reviewable at the Federal Circuit,” Lexology, Co-author (Jan. 10, 2018)
- “No Article III Standing Requirement for Appellees in Appeals from IPR Proceedings,” Lexology, Co-author (Aug. 8, 2017)
- “Prosecution History Disclaimer Extends to IPR Proceedings,” Lexology, Co-author (May 16, 2017)
- “PTAB Upholds Acorda’s Ampyra® Patents, Rejecting Challenges Based on Inventors’ Own Work,” Lexology, Co-author (March 15, 2017)
- “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, Co-author (Feb. 3, 2017)
- “Use of PTAB Decisions in District Court Litigation,” IP Watchdog, Co-author (Sept. 19, 2016)
- “Five Years In: The AIA’s Effects on Patent Litigation,” Bloomberg Law, Co-author (Sept. 8, 2016)
- “Some Federal Circuit Guidance on Procedural Safeguards for PTAB,” Law360, Co-author (June 30, 2016)
- “Federal Circuit Provides Guidance on the APA’s Procedural Safeguards for PTAB Proceedings,” Lexology, Co-author (June 16, 2016)
- “PTAB Provides Guidance on AIA Estoppel Provisions,” Managing Intellectual Property, Co-author (Oct. 28, 2015)
- “Quick Fixes Implemented, New Rules on the Way for PTAB Trial Practice,” Lexology, Co-author (April 1, 2015)
- Various case summaries, Federal Circuit Bar Association Circuit Case Digest, Co-author
Involvement
- Treasurer (2025–Present); Board of Directors (2021–2024); Chair of Annual Conference Committee (2019–2021); Vice-Chair of Annual Conference Committee (2018–2019) – PTAB Bar Association