People / Costello Matthew
Costello Matt

Matthew Costello


* Admitted in California. Practice temporarily authorized in Colorado pending admission under C.R.C.P. 205.6.

Matt Costello is a member of the Labor and Employment practice group in the firm’s Orange County and Denver offices. His practice includes employment litigation, client counseling, internal investigations, executive agreements, employment-law audit and compliance projects, and the employment aspects of corporate transactions. On the litigation front, he handles all facets of day-to-day case management in court, arbitration, and administrative agency employment matters.

He has obtained favorable results for Fortune 500 companies spanning a variety of industries, including energy, healthcare, and technology, in a wide range of single-plaintiff, complex, and class-action employment cases involving allegations of discrimination, harassment, wrongful termination, and wage and hour violations.

Matt also regularly counsels corporate clients on internal investigations, employee handbooks and policies, discrimination and harassment prevention, employee hiring and terminations, and restrictive covenants in employee contracts. He has also represented clients in complex business disputes, including trade secrets and unfair competition litigation. 

Matt regularly engages in, and is committed to, pro bono efforts, and was recently selected to the Board of Directors of the Public Law Center, a pro-bono law firm that provides access to justice for low-income residents of Orange County, California. For example, Matt assisted an Army veteran in seeking a discharge upgrade, including appearing before the Army Discharge Review Board in Washington, D.C. where he first-chaired a hearing before a five-officer military tribunal. He was also an integral part of a team of Haynes and Boone lawyers who partnered with several public interest groups to bring a housing discrimination lawsuit triggered by a local municipality’s efforts to shutter motels that provided long-term housing to residents of limited means, including many families with children or people with disabilities.

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  • Alumni, Leadership Counsel on Legal Diversity
  • Associate Board, Orange County Bar Foundation
  • Board Member, Public Law Center
  • Los Angeles Bar Association
  • Orange County Bar Association
  • Included in the "Ones to Watch" category of Best Lawyers in America, Woodward/White, Inc., 2021-2022
  • Received the Wiley W. Manuel Certificate for Pro Bono Legal Services, State Bar of California - 2016
  • “California Employment Law Update,” co-presenter, November 11, 2020.
  • “CAL OSHA, OSHA, and Labor and Employment Update,” presenter, National Armored Car Association’s Annual Meeting, San Diego, California, October 1, 2019.
  • “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.


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, 2006


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




Court Admissions

U.S. Court of Appeals for the Ninth Circuit

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

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

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

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

California Doubles Down on its Noncompete Prohibition: Employers May Need to Provide Notice by Feb. [...]
February 09, 2024

Effective Jan. 1, Senate Bill (SB) 699 and Assembly Bill (AB) 1076 restate California’s prohibition on employee non-competition provisions but also create new obligations, including the obligation to inform current and former employees of any void noncompete provision in any existing agreements. California Public Policy Prohibits Non-Competes California has long prohibited contractual non-competit [...]