Matthew Costello


Education and Clerkships

J.D., Loyola University Chicago School of Law, 2013, magna cum laude; Editor-in-Chief, Loyola University Chicago Law Journal

B.A., Psychology, Minor in Political Science, University of California, Los Angeles (UCLA), 2006

  • Extern to the Honorable Ronald A. Guzman, U.S. District Court for the Northern District of Illinois


California, 2013

Court Admissions

U.S. Court of Appeals for the Ninth Circuit

U.S. District Court for the Northern District of California

U.S. District Court for the Eastern District of California

U.S. District Court for the Central District of California

U.S. District Court for the Southern District of California


Matthew Costello, committed to professionalism, integrity and delivering high quality work product, maintains a diverse practice that includes a wide range of business and employment litigation matters in state and federal court.

Matt’s experience litigating complex business disputes includes the recent representation of a client suing for breach of a partnership agreement and breach of fiduciary duty, for which Matt managed all facets of electronic and written discovery, drafted numerous successful motions, took and defended depositions, and communicated directly with the client and its inside attorney on a daily basis to ensure a positive working relationship. Matt has also been an integral part of litigation teams handling contract disputes, trade secrets litigation, and unfair competition claims.

Matt also advises small and large employers on their employment-related matters and tirelessly litigates against employee claims in court, arbitration, and administrative proceedings. He has obtained favorable results for Fortune 500 companies in discrimination suits, wrongful termination cases, and wage and hour class actions, including successfully defending against a motion for Fair Labor Standards Act collective action certification brought in arbitration.

Matt is dedicated to pro bono work. He works closely with Orange County’s Public Law Center to help those in dire need of legal services. For example, Matt recently assisted a former U.S. Army serviceman in seeking a discharge upgrade, including appearing before the Discharge Review Board in Washington, D.C. where he first-chaired a hearing before a five-officer panel. Matt is also part of a team of Haynes and Boone lawyers working with several public interest groups that obtained a preliminary injunction against the City of Costa Mesa preventing the eviction of any current motel residents under a new ordinance pending trial.

Professional Recognition

  • Received the Wiley W. Manuel Certificate for Pro Bono Legal Services, State Bar of California - 2016

Selected Publications and Speeches

  • “Navigating Hiring Pitfalls” author, handbook provided at Haynes and Boone’s Employer Food for Thought panel event, New York, New York, 2015.
  • “Helping Military Veterans Navigate the Legal Framework of Discharge Upgrades,” co-author, OC Lawyer, 2014.

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