Katherine A. O’Brien

Managing Associate Partner

San Diego Office

Office Location

8880 Rio San Diego Drive
Suite 725
San Diego, CA 92108

T (619) 961-1193
F (916) 442-1028

Practice Areas

Workers’ Compensation Defense


Admitted to Practice by the State Bar of California: 2012
Number of years in Worker's Compensation: 9
Number of years with Mullen & Filippi, LLP: 2015


Career Basics

Katherine joined Mullen and Filippi in March 2016 as an Associate Attorney and became an Associate Partner in July 2018. She has practiced law in the area of workers’ compensation since 2012, when she initially became a member of the State Bar of California. Prior to joining Mullen and Filippi, Katherine worked for a prominent California workers’ compensation defense firm, where she co-managed their developing Los Angeles office. She has practiced throughout Southern California representing the interests of insurance carriers, self-insured entities, and the California Insurance Guarantee Association and has appeared at numerous WCAB district offices throughout the Los Angeles, San Diego, and Inland Empire regions.


Katherine received her law degree from the University of La Verne College of Law in 2012. During her time at the University of La Verne, Katherine earned the CALI Achievement Award for obtaining the highest grade in several of her law school courses. While in law school, Katherine spent summers interning at the Riverside District Attorney in their Indio office, where she conducted several preliminary hearings, argued various oral motions, and researched and drafted numerous written motions and trial briefs. In 2008, she earned a Bachelor of Arts in English Literature from University of Redlands, where she achieved the Dean’s Honor list for a number of her semesters spent there.

Professional Membership

Katherine is a member of the State Board of California.

Personal Note

Growing up in Palm Springs, I am an outdoor enthusiast and enjoy spending my free time participating in various outdoor activities including walking and hiking. I also have a passion for both reading and writing, and aspire to one day author a fiction novel. Otherwise, I can be found spending time with my family, friends, and my cocker spaniel, Noel.

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