Dion Cominos joined GRSM in 1987 and served as Firmwide Managing Partner/Chairman from 2006-2026. During that time, it expanded more than tenfold (as the fastest-growing AmLaw 100 firm) and transformed from a modest regional presence into the nation’s 6th largest law firm with more than 2,000 attorneys practicing in nearly 90 offices nationwide and as the first and only legal services business in the country with a physical presence and attorneys in all 50 states.
In 2026, Dion returned to practicing law full time as a Senior Partner in GRSM’s Commercial Litigation, Construction, and Professional Liability Practice Groups. He has consistently been recognized as an outstanding practitioner by virtually every leading industry publication, including being named a Legal 500 Elite in the field of Commercial Litigation, one of the Best Lawyers in America©, a Martindale-Hubbell top-rated AV Preeminent Lawyer, and a Super Lawyer®.
Litigation
Dion specializes in defending businesses and individuals in a wide variety of claims involving commercial disputes and professional liability matters including:
- Commercial/Business/Real Estate/Construction Litigation
- Errors & Omissions Claims (including accountants, attorneys, financial planners, tax advisors, teachers, architects, engineers, etc.)
- D&O Litigation
- Artificial Intelligence Claims
- Unfair Competition/Unfair Debt Collection-FDCPA Claims/§17200 Lawsuits
- Misappropriation/Trade Secret Matters
- Securities Litigation
- Commercial Contract/Business Torts
- Consumer Class Actions
- Franchise and Related Contractual Disputes
- First Amendment/Media/Defamation Actions
- Technology/Data Privacy/Security Claims
He has also handled a broad variety of other claims involving construction, environmental site contamination/bodily injury, artificial intelligence, product liability, employment and insurance, and has arbitration and trial experience in numerous civil and administrative proceedings in federal districts and state counties throughout California. In the arena of data privacy/security claims, Dion has defended businesses and individuals in connection with numerous claims involving pretexting, identity theft, database hacking, improper dissemination of private information, and alleged violations of various state and federal statutes including the TCPA, the “Can-Spam” Act, California Business & Professions Code §17529, et seq., and many others.
Appellate/ADR/Administrative Matters
In addition to his trial and arbitration work, Mr. Cominos has also successfully handled appellate cases before the California Supreme Court, the 9th Circuit Court of Appeals and the California State Court of Appeal, and reported decisions include Winston Square Homeowner’s Assn. v. Centex West, Inc. (1988) 213 Cal.App.3d 282, and Wells v. One2One Learning Foundation (2006) 39 Cal.4th 1164. Mr. Cominos also has extensive experience in all forms of alternative dispute resolution, including mediations both in California and abroad, has served as both a mediator and arbitrator, and has represented clients before administrative bodies such as planning commissions, city councils, boards of supervisors, health departments, OSHA, WCAB, HUD, DFEH, BAAQMD and various other disciplinary and professional boards.
In addition to being published in a number of legal journals and periodicals, Mr. Cominos has spoken as a guest panelist at annual meetings of the American Bar Association, the Association of Defense Counsel, the DRI and PLUS.
Presentations
- Presenter, AI at 3: Are the Terrible 2s Behind Us? An Exploration of How Artificial Intelligence Continues to Evolve in the Legal and Insurance World and the Practical and Ethical Implications Involved in its Use, GRSM Legal Education Conference, New York, NY, May 2026
- Presenter, AI at 3: Are the Terrible 2s Behind Us? An Exploration of How Artificial Intelligence Continues to Evolve in the Legal and Insurance World and the Practical and Ethical Implications Involved in its Use, GRSM Legal Education Conference, Hartford, CT, May 2026
- Presenter, AI at 3: Are the Terrible 2s Behind Us? An Exploration of How Artificial Intelligence Continues to Evolve in the Legal and Insurance World and the Practical and Ethical Implications Involved in its Use, GRSM Legal Education Conference, Chicago, IL, March 2026
- Presenter, Did You Just Press Rewind? Impact of the New Administration on Employers, GRSM Legal Education Conference, Los Angeles, CA, June 2025
- Presenter, Hey Hey, My My: Should I Trust This New AI?, GRSM Legal Education Conference, New York, NY, May 2025
- Presenter, Hey Hey, My My: Should I Trust This New AI?, GRSM Legal Education Conference, Hartford, CT, May 2025
- Presenter, AI DIY: A Guide to Avoiding Employment Pitfalls in the Workplace, GRSM Legal Education Conference, San Francisco, CA, September 2024
- Presenter, AI DIY: A Guide to Avoiding Employment Pitfalls in the Workplace, GRSM Legal Education Conference, Los Angeles, CA, June 2024
- Presenter, AI DIY: A Guide to Avoiding Ethical Pitfalls with Artificial Intelligence, GRSM Legal Education Conference, New York, NY, May 2024
- Presenter, AI DIY: A Guide to Avoiding Ethical Pitfalls with Artificial Intelligence, GRSM Legal Education Conference, Hartford, CT, April 2024
- Presenter, AI FYI: Cutting Edge Technological Issues Impacting Employers, GRSM Legal Education Conference, Los Angeles, CA, June 2023
- Presenter, Hashtag Ethics: Navigating Social Media Legal Ethics in 2023, GRSM Legal Education Conference, New York, NY, May 2023
- Presenter, Hashtag Ethics: Navigating Social Media Legal Ethics in 2023, GRSM Legal Education Conference, Hartford, CT, May 2023
- Presenter, Don’t Let the Bytes Bite You: Ethics in the Digital Age, GRSM Legal Education Conference, San Francisco, Chicago, New York and Hartford, October 2019
- Presenter, Reframing the Psychology of Victory in the Realm of Civil Litigation, GRSM Legal Education Conference, Los Angeles, June 2019
- Presenter, Handling “Tag Along” Employment Claims, Best Practices for Defending Against Ancillary Causes of Action Increasingly Included in EPL Lawsuits, GRSM Legal Education Conference, San Francisco and Los Angeles, 2018
- Presenter, ETHICS – Successfully Navigating Through Ethical Minefields, GRSM Legal Education Conference, New York and Hartford, May 2018
Admissions
- California
- U.S. District Courts, California
- U.S. Court of Appeals, Ninth Circuit
Memberships
- Defense Research Institute – Professional Liability Section
- Professional Liability Underwriting Society – Northern California Chapter
- Association of Defense Counsel – Northern California Construction Practice Chapter
- American Bar Association
- Claims and Litigation Management (CLM) Alliance
- Tort and Insurance Practice Section
- State Bar of California
- Business Law Practice Section
Community Involvement
Dion has been actively involved with the San Francisco charitable Foodbank program, and previously served as a member of the Board of Directors for the Legal Aid Society of San Francisco.
Education
- J.D., University of California, Hastings College of the Law
– Twice received the American Jurisprudence award for academic excellence - B.A., University of California, Berkeley
Honors
- Top Rated Lawyer-AV® Preeminent™, Martindale-Hubbell
- Best Lawyers in America® distinction in Construction Law, 2021-2026
- Super Lawyers® distinction in Civil Litigation Defense and Business Litigation, 2004-2019, 2022-2025
- San Francisco Elite Rankings in Commercial Litigation, Legal 500, 2026
- 100 Managing Partners You Need to Know, Lawdragon, 2026
- Distinguished Leader Finalist, California Legal Awards, The Recorder and Law.com, 2026