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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.
Daniel devotes a portion of his time to serving the bar. He has been actively involved in the PTAB Bar Association for many years, and he currently serves as its Treasurer and on its Board of Directors. Daniel also works on a variety of pro bono matters.
Accolades
- Elected as Treasurer of PTAB Bar Association (2025–Present) and to Board of Directors (2021–24)
- Named "Rising Star" by Managing Intellectual Property's IP Stars (2025)
- Recipient of the Paul Hastings Client Service Excellence Award
- Recognized as Legal Lion by Law360 various times
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.
- Samsung Electronics Co., Ltd. v. Broadphone LLC (PTAB). Represented Samsung in IPRs filed against three patents. All challenged claims found unpatentable.
- SNF SA v. Chevron USA Inc. (PTAB). Defended Chevron USA’s patent in an IPR. Secured decision confirming patentability of all claims.
Engagement & Publications
- Co-author, “Federal Circuit Clarifies the Scope of IPR Estoppel,” Lexology, May 9, 2025.
- Co-author, “USPTO Rescinds Memorandum Addressing Discretionary Denial Procedures,” Lexology, March 3, 2025.
- Speaker, “Effective Use of an Expert in a PTAB Trial,” PTAB Bar Association Annual Conference, March 10, 2023.
- Moderator, “Appeals from the PTAB,” PTAB Bar Association Annual Conference, September 23, 2021.
- Co-author, “Federal Circuit Rules PTAB APJs Violate Appointments Clause,” Lexology, November 1, 2019.
- Co-author, “A Divided Supreme Court Upholds Inter Partes Review’s Constitutionality but Constrains the Patent Office's Authority,” Lexology, April 25, 2018.
- Co-author, “The APA in PTAB Proceedings: Notice and an Opportunity to Be Heard,” Landslide® magazine, Volume 10, Issue 3, January/February 2018.
- Co-author, “PTAB Section 315(b) Time-Bar Determinations Reviewable at the Federal Circuit,” Lexology, January 10, 2018.
- Co-author, “No Article III Standing Requirement for Appellees in Appeals from IPR Proceedings,” Lexology, August 8, 2017.
- Co-author, “Prosecution History Disclaimer Extends to IPR Proceedings,” Lexology, May 16, 2017.
- Co-author, “PTAB Upholds Acorda’s Ampyra® Patents, Rejecting Challenges Based on Inventors’ Own Work,” Lexology, March 15, 2017.
- Co-author, “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, February 3, 2017.
- Speaker, “Recent Developments in Post Grant Proceedings at the Patent Trial and Appeal Board,” IP Strategy Innovation Summit, Boston, MA, September 28, 2016.
- Co-author, “Use of PTAB Decisions in District Court Litigation,” IP Watchdog, September 19, 2016.
- Co-author, “Five Years In: The AIA’s Effects on Patent Litigation,” Bloomberg Law, September 8, 2016.
- Co-author, “Some Federal Circuit Guidance on Procedural Safeguards for PTAB,” Law360, June 30, 2016.
- Co-author, “Federal Circuit Provides Guidance on the APA’s Procedural Safeguards for PTAB Proceedings,” Lexology, June 16, 2016.
- Co-author, “PTAB Provides Guidance on AIA Estoppel Provisions,” Managing Intellectual Property, October 28, 2015.
- Co-author, “Quick Fixes Implemented, New Rules on the Way for PTAB Trial Practice,” Lexology, April 1, 2015.
- Co-author for various case summaries for Federal Circuit Bar Association Circuit Case Digest.
Involvement
- PTAB Bar Association: Treasurer (2025–Present); Board of Directors (2021–2024); Chair of Annual Conference Committee (2019–2021); Vice-Chair of Annual Conference Committee (2018–2019)