Melissa R. Costello

Of Counsel She / Her / Hers

Melissa R. Costello counsels and represents private businesses, public corporations, and nonprofit organizations in a variety of litigation and transactional matters. Her practice emphasizes civil employment matters involving harassment, discrimination, wage-and-hour law, state and federal leave laws, ADA, FMLA, COVID-19 issues, discipline issues, contracts, trade secret protection, restrictive covenants, and employment separation.

Melissa has assisted clients in formulating policies, procedures, handbooks, contracts, and strategies to minimize the risk of litigation. She has represented clients in administrative matters, including before the U.S. Department of Labor, U.S. Equal Employment Opportunity Commission, Arizona Attorney General’s Office Civil Rights Division, and Industrial Commission of Arizona.

Melissa has co-chaired jury and bench trials in state and federal court.


Representative Matters

State of Arizona v. Bishop Thomas O’Brien

Shaffer v. State of Arizona Citizens Clean Elections Commission

Professional Highlights

Pro Bono Experience

Melissa is committed to providing pro bono employment law counsel for local and national nonprofit organizations.

Professional Activities

American Bar Association, 2001-Present

Arizona State Bar Association, 2001-Present

Maricopa County Bar Association, 2001-Present

Speaking Engagements

Melissa is a frequent presenter on employment law topics throughout the Arizona business community. Recent presentations include:

"Wellness in the Workplace: Expanding Your Workplace to Include Mental Health," Cancer Support Community of Arizona, August 21, 2020

"Managing Your Personnel and Employment Law Issues in a Pandemic," Arizona In-Home Care Association, July 29, 2020

"How Arizona Employers Must Comply With New Supreme Court Ruling Extending Title VII to LGBTQ Employees," in-house client presentation, June 30, 2020

"Hiring and Onboarding: Setting Up New Employees for Success From Day One and Avoiding Risk From Day One," in-house client presentation, co-sponsored with Paychex, November 5, 2019

Board Memberships & Community Service

Cancer Support Community—Board of Directors, 2012-2018; Leadership Council, 2008-2011

Vice Chair, 2015-2016

Governance Chair, 2014-2015

Scottsdale Leadership, 2004-2006

Board of Directors, Recruitment and Selection Vice Chair, 2005-2006



The University of Arizona (J.D., cum laude, 2001)

The University of Arizona (B.A. and B.S., cum laude, 1997)


Spanish (conversational)