Over the better part of two decades as an attorney and commercial litigator, Mat Harrington has taken over 20 cases to verdict or arbitration decision as lead or co-lead counsel, some of which involved claims worth hundreds of millions of dollars. He has argued numerous appeals and litigated successfully before the U.S. Supreme Court. He has represented individuals and entities in a wide array of industries and in venues ranging from county courthouses to an arbitration in the New York Times building in Manhattan. His practice emphasizes employment law, trust and estate litigation, and Indian law.

Mat’s litigation experience is broad. He has advocated for clients in lawsuits relating to employment law, non-compete agreements, trusts and estates, fiduciary duties, public disclosure laws, the Public Records Act, antitrust law, class actions, breach of contract, deceptive trade practices, fraud, and trade secret misappropriation. He is frequently called upon to advise professionals and Boards of Directors in disputes pertaining to duties, departures, and responsibilities. He also offers mediation services to parties seeking a neutral’s assistance to mediate a dispute.

Mat handles all aspects of complex litigation — from pre-suit investigation and discovery through dispositive motion practice and trial. He was counsel of record in Washington State Department of Licensing v. Cougar Den, 139 S. Ct. 1000 (2019), a landmark U.S. Supreme Court decision affirming a case he argued and prevailed on before the Washington Supreme Court, announcing that the Treaty of 1855 granted Yakama Nation members the right to travel the public highways of the United States free from taxes which encumber that treaty right. His representation of the Tulalip Tribe helped contribute to the passage of a law providing that tribes and the State of Washington may share sale tax receipts for sales occurring on reservations.

Mat is recognized by The Best Lawyers in America® (commercial litigation), Thomson Reuters "Super Lawyers," and in 2016 listed as a Top 100 Lawyers in Washington State by Washington Super Lawyers. 

In addition to his experience in commercial litigation, Mat has a deep commitment to the public interest, arguing a 2019 case before the Washington Supreme Court that that State of Washington must improve the quality of public defense services provided to indigent juveniles accused of offenses.


  • Washington
  • U.S. Supreme Court
  • U.S. District Court for the Eastern and Western Districts of Washington
  • U.S. Court of Appeals for the Ninth Circuit


  • University of Chicago Law School, J.D. (2002)
  • St. Olaf College, B.A. in Economics and Political Science, summa cum laude (1996)

Recognition & Honors

  • Rising Star, Washington Super Lawyers (2006 - 2007, 2011 - 2012)
  • AV Preeminent Peer Review Rated, Martindale-Hubbell's highest ranking
  • Washington Super Lawyers (2014 - 2023)
  • Top-Rated Lawyer, West Coast, National Law Journal (2017)
  • Top 100 Lawyers, Washington Super Lawyers (2016)
  • The Best Lawyers in America in Commercial Litigation (2021 - 2024)

Representative Work

  • As lead counsel, obtained complete defense verdict after two-week jury trial regarding breach of non-compete, non-solicit, and company confidential information. Even though breach had already been found, jury ruled for our client and awarded no damages.
  • Successfully argued appeal to Washington Supreme Court in Cougar Den, Inc. v. Department of Licensing. The Court agreed that treaty rights barred the Washington Department of Licensing from assessing taxes for fuel. Served as counsel of record in subsequent appeal to U.S. Supreme Court, which ruled in favor of the treaty right in a historic decision.
  • Tried and won a bench trial between co-founders and officers of a privately held technology firm, involving fiduciary duty and executive employment claims.
  • Represented a health care entity in a lawsuit filed to invalidate a commercial contract that purported to restrict the entity’s entry into a new market. Prevailed at trial.
  • Trial counsel in federal court bench trial regarding whether Washington State and Snohomish County can collect sales tax on reservation at Quil Ceda Village. Case settled during Ninth Circuit appeal, resulting in ground-breaking compact to share Washington sales taxes with tribes.
  • Complete verdict in client’s favor in intra-family business dispute, tried to jury via Zoom. Jury found no breach of fiduciary duty in management of real estate LLCs.
  • Tried confidential employment arbitration in which claims of pregnancy discrimination, defamation, and improper calculation of physician compensation were successfully defeated.
  • Lead counsel for Canadian manufacturer sued in family of antitrust class actions in the U.S. Prevailed after several rounds of motions to dismiss.
  • Successfully obtained removal of manager of company overseeing deceased rocker’s licensing and royalty rights, via arbitration on behalf of trustee.
  • Represented business partner in intensely litigated dispute over 50% share in the management contract for $500 million casino project. Obtained favorable settlement prior to trial.
  • Represented tribal administrator ousted by later-elected tribal council. Settled favorably at mediation two months before trial.
  • Co-counsel for electronics manufacturer in antitrust price-fixing class action. Settled favorably months prior to trial.
  • Prevailed against Big 3 accounting firm in confidential employment arbitration brought by former partner.
  • Represented start-up company in defeating motion for preliminary injunction for alleged violation of non-compete agreement.
  • Successfully defended breach of fiduciary duty claims asserted by high-net worth individual against corporate fiduciary trustee of trust. Obtained summary judgment dismissal and prevailed on appeal.
  • Represented real estate partnership in claims brought by estate of former partner.
  • Represented CEO in age discrimination suit against former employer.
  • Represented wireless carrier in consumer class actions.
  • Represented wireless carrier in employment dispute.
  • Represented software company in antitrust lawsuits brought by indirect purchasers taken to trial state courts.
  • Represented software company in nationwide consumer class action alleging violations of Washington Consumer Protection Act and RICO.
  • Represented pharmaceutical company in indemnification action and related qui tam fee dispute.
  • Represented utility in defeating preliminary injunction threatening construction of new generating capacity.

Publications & Presentations

  • "2020 Employment Law Update," moderator (November 2020)
  • "Non-Competes and Other Restrictive Covenants: What's Enforceable After January 1, 2020?" co-presenter, 2019 Employment Law Update for Washington Employers (November 2019)
  • "Sales Tax and Other Double Taxation Issues," presenter, 21st Annual Tax Conference, National Intertribal Tax Alliance (August 2019)
  • "U.S. Supreme Court Upholds Yakama Treaty Rights in Washington State Department of Licensing v. Cougar Den, Inc.," co-author, article, Indian Law Newsletter (Spring 2019)
  • "Treaty Rights and Reservation Disestablishment Before the U.S. Supreme Court," panelist, 2019 Indian Law Conference, Federal Bar Association (April 2019)
  • "Treaty Rights and Washington State Department of Licensing v. Cougar Den," panelist, Tenth Annual Indian Law Conference, Spokane County Bar Association Indian Law Section (March 2019)
  • "Washington Paid Sick Leave Law & Other Hot Topics - Your Questions Answered," panelist, 2017 Employment Law Update for Washington Employers (October 2017)
  • "Developments in Washington State Employment Law," presenter, 2017 Employment Law Update for Washington Employers (October 2017)
  • "Employment Practices Litigation Insurance (EPLI): Your Questions Answered," co-presenter with Carolyn Cairns, Stokes Lawrence Employment Law Institute (December 2015)
  • "Insurance Issues in Employment Litigation," presenter, Employment Law Institute CLE, King County Bar Association (September 2015)
  • WSBA’s Annual Antitrust, Consumer Protection and Unfair Business Practices Seminar, Antitrust presenter (November 2014)
  • "Noncompetes & Nonsolicitation," presenter, Stokes Lawrence Employment Law Institute CLE (August 2014)
  • "Recent Arbitration Law Developments - Washington State & Federal Law," co-presenter with Olivia Gonzalez, Stokes Lawrence Employment Law Institute CLE (August 2014)
  • "Should You Include Arbitration Clauses in Employment Contracts?" co-presenter with Olivia Gonzalez, Stokes Lawrence Employment Law Institute Client Workshop (August 2014)
  • "Superior Court Boot Camp:  A Motion and Trial Practice Skills Seminar," presenter (2014)
  • WSBA's Annual Antitrust, Consumer Protection and Unfair Business Practices Seminar, co-chair (November 2013)
  • "The Importance of Filing Creditor's Claims for Real Estate Lenders and Homeowners' Associations in a Challenging Economy," co-authored with Scott A.W. Johnson and Joan Hemphill, WSBA Real Property Probate and Trust Section Newsletter (Fall 2012)
  • "Jury Selection and Opening Statements in an Employment Case," Employment Litigation from Start to Finish, presented by NBI (2012)
  • "Antitrust Compliance Review," closely held manufacturing company (most recently 2012)
  • "Managing Risks for Employers: Trends and Tips," presenter, Stokes Law Briefs for Closely Held Businesses (June 2011)
  • "Sexual Harassment Compliance Training," various employers (multiple dates)
  • "It's Out of My Hands? A party's duty to preserve documents in the possession of others," co-authored with Charles Ha, LexisNexis Mealey's Litigation Report, Discovery, Vol. 5, Issue 8
  • Antitrust Law Developments, contributing drafter for the ABA Section of Antitrust Law's annual review (2008)

Professional & Community Activities

Mat dedicates a portion of his practice to providing individuals with legal services pro bono. He argued before the Washington Supreme Court the question of whether the State of Washington is providing adequate public defense services for indigent juveniles. He has successfully pursued constitutional claims on behalf of students who were subjected to suspicionless drug tests. Mat has also provided pro bono advice regarding a smart phone app designed to record possible civil rights violations.

In early 2011, Mat served as a Special Deputy Prosecuting Attorney during a fellowship with the King County Prosecutor’s Economic Crimes Unit. The Prosecutor’s Trial Fellowship Program enlists lawyers from law firms as trial attorneys assigning them a regular caseload of felony criminal trials.

He has represented victims of domestic violence in obtaining protection orders and determining child custody.

Mat's other professional activities include: 

  • Board Member, King County Bar Foundation
  • Board Member, Roosevelt Jazz Booster Club


Background & Interests

Mat litigated cases with international law firm Heller Ehrman for six years prior to joining Stokes Lawrence in 2008.