Image: Sean D. Unger

Sean D. Unger

Partner, Litigation Department


Sean D. Unger is a partner in the Litigation practice of Paul Hastings and is based in the firm’s San Francisco office.

Mr. Unger represents and advises clients in mass torts, class actions, antitrust and competition matters, trade secret cases, and intellectual property disputes in State and Federal courts around the country. His practice emphasizes appellate litigation. He has briefed or argued cases in numerous state and federal courts of appeal. He has represented both parties and amicus before the United States and California Supreme Courts. Mr. Unger has also represented clients in need of post-trial disaster mitigation. He has successfully brought post-trial motions for new trial and motions for judgment as a matter of law, reducing or eliminating multi-million dollar judgments.

Clients have included a broad range of companies, including Andersen Windows, Samsung, Gallo Wineries, GE, LG Display, Babcock & Wilcox, and Quanta Computers.


External Recognition

  • Best Lawyers in America "Ones to Watch" - 2024 for Commercial Litigation
  • Best Lawyers in America "Ones to Watch" - California 2023
  • Best Lawyers in America "Ones to Watch" - Northern California 2023
  • Best Lawyers in America "Ones to Watch" - Northern California 2022
  • Selected to the list of Northern California Rising Stars by Super Lawyers Magazine in 2013-2018.


Mr. Unger received a B.A. degree, Phi Beta Kappa, from the University of California, Berkeley. He received a J.D. from Harvard Law School.

Prior Legal Experience

  • Served as a law clerk to the Honorable Richard S. Arnold of the United States Court of Appeals for the Eighth Circuit and the Honorable Boyce F. Martin, Jr. of the United States Court of Appeals for the Sixth Circuit; and 
  • Served as an adjunct professor of law at University of Arkansas, Little Rock, William H. Bowen School of Law.


Appellate and Post-Trial Representations

Mr. Unger serves as a firm resource on questions of appellate and federal jurisdiction. Recent appellate and post-trial representations include: 

  • Representing a defendant in a Price Anderson Act case before the Third Circuit;
  • Representing a video game company before the California Court of Appeal;
  • Representing an OEM to eliminate 90% of a verdict in a multi-million dollar patent dispute; 
  • Representing a manufacturer in a case before the U.S. Supreme Court; 
  • Representing a manufacturer of windows to defend denial of class certification before the California Court of Appeal.

Consumer Class Action and Competition Representations

Mr. Unger’s recent representations in high-exposure consumer class actions and antitrust disputes include: 

  • Representing a manufacturer in successfully opposing class certification in a consumer dispute; 
  • Representing a components manufacturer in antitrust MDL proceedings, including successfully briefing various summary judgment motions; and 
  • Representing a lender in negotiating and implementing class settlement in suit challenging debt-collection practices.


    Engagement & Publications

    • Co-author with Stephen B. Kinnaird, Robert Sherman, Igor V. Timofeyev, and Lisa Leung, Supreme Court Opinion on Preclusive Effect of TTAB’s Registration Decisions Has Important Implications for Trademark Owners, Bloomberg BNA: The United States Law Week (April 14, 2015)
    • Co-author with Katharine F. Murray and Scott M. Klausner, Ninth Circuit Comes Around on CAFA, Law 360, (April 14, 2015)
    • Co-author with John P. Phillips and Kelly Winslow, Ninth Circuit Will Clarify Process Service for International Corporations, Law 350 (April 14, 2015)
    • Co-author with Danielle C. Doremus and Stephen B. Kinnaird, Peeling the Onion: Appellate Lawyers’ Take on Disparate Cases, Bloomberg BNA: The United States Law Week (March 3, 2015)
    • Co-author with John P. Phillips and Christopher M. Mooney, Class Actions and the Ninth Circuit: Different Consumer Contracts Defeat Predominance, Bloomberg BNA: Class Action Litigation Report (March 14, 2014)
    • Co-author with Stephen B. Kinnaird, Charles A. Patrizia, Igor Timofeyev, and Ian A. Herbert, Supreme Court in Daimler AG v. Bauman Limits General Jurisdiction Over Foreign Companies, ABA Section of Public Utility, Communications and Transportation Law, Vol. 53, No. 3 (Spring 2014)
    • Co-author with Stephen B. Kinnaird, Charles A. Patrizia, Igor Timofeyev, and Danielle C. Doremus, High Court Continues To Restrict Personal Jurisdiction, Law 360 (March 5, 2014)
    • Co-author John P. Phillips and Sophie J. Sung, Courts Continue To Accentuate the Ascertainable Class, Law 360 (February 20, 2014)
    • Co-author with John P. Phillips and Jose de Wit, Ninth Circuit Clarifies Scope of Rule 26 Expert Discovery, Law 360 (February 19, 2014)
    • Co-author with Thomas A. Counts, Grace A. Carter, and Angela J. Markle, Settling With Named Plaintiffs in Federal Class Actions: Does Timing Matter?, Bloomberg BNA: Class Action Litigation Report (November 8, 2013)
    • Co-author with Stephen B. Kinnaird and Danielle C. Doremus, An Appellate Lawyer’s Role in a Trial, Bloomberg BNA: The United States Law Week (May 28, 2013)
    • Co-author with Grace A. Carter and Angela J. Markle, Emerging Trends in Class Action Settlements in the Ninth Circuit, Bloomberg BNA: Class Action Litigation Report (January 1, 2013)
    • Co-author with Dennis S. Ellis and Katherine F. Murray, Bifurcated Discovery in Class Actions, Bloomberg BNA: Class Action Litigation Report (August 26, 2011)
    • Co-author with John P. Phillips, Clemens v. Daimler – The Ninth Circuit Addresses a New Twist in the law of Cross-Jurisdictional Tolling, Mealey’s Litigation Report: Class Actions (August 7, 2008)
    • Co-author with Ned N. Isokawa and Katharine Chao, Speeding Things Along, Los Angeles Daily Journal (June 2, 2008)
    • Co-author with John A. Reding, Jay C. Gahndi, Edward Han, and Jason K. Sonoda, The Rise and Fall of the U.S. Capital Markets: The Potential Impact of Recent Developments on U.S. and Foreign Securities Laws, Bloomberg Law Reports: Securities Law (February 4, 2008)
    • Co-author with John A. Reding and Edward Han, Court Weighs Whether Mergers Wipe Out Derivative Actions, San Francisco Daily Journal (April 6, 2006)
    • Judge Arnold’s Four Rules: A Model for a Life in the Law, 27 U. ARK. LITTLE ROCK L. REV. 387 (Spring, 2005)


    • Serves as an advisory board member of the East Bay Community Law Center and is a former board member of AIDS Legal Referral Panel; 
    • Active member of the Ninth Circuit’s pro bono program, having successfully briefed and argued cases having to do with issues ranging from constitutional law to immigration disputes; and 
    • Authored numerous briefs to the United States Supreme Court in conjunction with the Firm’s commitment to the University of Pennsylvania’s Supreme Court Clinic.

    Practice Areas


    Internet of Things

    Appellate Litigation

    Antitrust and Competition

    Class Actions

    Complex Litigation and Arbitration

    International Arbitration

    Securities Litigation




    California Bar


    Harvard Law School, J.D. 2003

    University of California, Berkeley, B.A. 2000

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