Experience
Integrity
Results
Firm Overview
About Us
Umberg/Zipser LLP is a premier business litigation and intellectual property boutique law firm. Drawing on decades of experience in some of the nation’s largest and most prestigious law firms, as well as national and state government service, our lawyers provide exceptional work with the unparalleled personal service of a boutique.
Our Culture
Umberg/Zipser believes in giving back, both to our community and to our profession. We regularly handle pro bono matters, and our attorneys devote countless hours to supporting — and leading — professional and community organizations. It would be difficult to find another firm in Orange County, regardless of size, that can boast the number of community leaders that exist at Umberg/Zipser.
Why Us?
By combining big-firm experience with small-firm efficiencies, we can handle complex matters for large companies, but we also are nimble enough to represent small companies and entrepreneurs. Our clients come to us because we deliver the highest quality work product together with extraordinary service.
Practice Areas
We Have the Experience to Handle a Wide Array of Matters
Professionals
We Have Exceptional Attorneys Who Stand Ready to Serve Our Clients
Ryan S. Dean
(949) 679-0052
[email protected]
Ryan specializes in global patent and trademark prosecution for clients of all sizes, and focuses primarily in the areas of mechanical and aerospace engineering
Ethan Feng
- (949) 679-0052
- [email protected]
Ethan Feng is an associate at Umberg/Zipser where he focuses his practice in complex commercial litigation, professional liability disputes, and employment litigation.
Martin Fessenmaier, Ph.D.
- (949) 679-0052
- [email protected]
Martin has almost two decades of experience in domestic and International patent prosecution, working in the fields of biochemistry and molecular biology, bioinformatics, medical devices, organic chemistry, and general mechanical arts.
Mark A. Finkelstein
- (949) 679-0052
- [email protected]
Mark Finkelstein is a partner at Umberg/Zipser with more than 30 years of intellectual property and complex litigation experience.
Scott B. Garner
- (949) 679-0052
[email protected]
Scott B. Garner is a partner at Umberg/Zipser in Irvine, California. He represents clients in complex business litigation matters, with a particular focus on professional liability disputes and ethics counseling.
Amy Lesperance Han
(949) 679.0052- [email protected]
Amy Lesperance Han is an associate with Umberg/Zipser and focuses her practice on complex commercial litigation. Amy has experience litigating a wide variety of complex disputes, representing clients from the discovery phase through trial and appeal.
Phillip R. Kaplan
Partner
(949) 679-0052- [email protected]
Phillip R. Kaplan is a recognized leader in the Orange County legal community, and is an accomplished business trial lawyer with a record of handling his client’s most difficult cases.
Nasser Khateeb
- 949.679.0052
- [email protected]
Nasser Khateeb is an attorney at Umberg/Zipser LLP and focuses his practice on intellectual property law, helping clients secure, protect, and grow their innovations.
Ellen S. Kim
- (949) 679-0052
- [email protected]
Ellen Kim is an Associate at Umberg/Zipser LLP where she focuses her practice in complex commercial litigation. Prior to joining the firm, Ellen was an Associate at Jones Day. Ellen also served as a law clerk to the Honorable Diana Saldaña in the United States District Court for the Southern District of Texas and to the Honorable Robert Huie in the United States District Court for the Southern District of California.
Molly Magnuson
- (949) 679-0052
- [email protected]
Molly Magnuson is an experienced, results-oriented litigation attorney. Molly’s experience comes not only from working for significant clients, but also from working in some of America’s top law firms, which has created exposure to high-stakes, complex commercial litigation.
Priti Phukan, Ph.D.
- (949) 679-0052
- [email protected]
Priti Phukan concentrates her practice on patent and trademark prosecution across various technology industries, including chemistry, life sciences, diagnostics, medical devices, and mechanical engineering.
Marcus S. Quintanilla
- (949) 679-0052
- [email protected]
Marcus Quintanilla is Of Counsel at Umberg/Zipser and has over twenty years’ experience litigating and arbitrating complex domestic and cross-border cases.
Carole E. Reagan
- (949) 679-0052
- [email protected]
Carole E. Reagan’s practice focuses on intellectual property and complex commercial litigation. She has successfully represented business clients across a diverse array of industries.
Todd W. Smith
- (949) 679-0052
- [email protected]
Todd Smith’s practice focuses on complex business litigation in state and federal courts representing companies and individuals in partnership disputes, shareholder and derivative litigation, real estate disputes, trade secrets, and unfair competition claims.
Jeremy G. Suiter
- (949) 679-0052
- [email protected]
Jeremy is a seasoned business litigator with over 20 years of experience handling complex commercial and trade secret disputes. He represents closely held companies in matters involving contracts, fraud, and internal business conflicts, offering practical and cost-effective legal strategies. Known for his clear guidance and results-driven approach, Jeremy helps clients navigate disputes while minimizing business disruption.
Ryan T. Tran
- (949) 679-0052
- [email protected]
Ryan T. Tran is an associate at Umberg/Zipser LLP, where he focuses on complex civil litigation, including real estate, business, and contract disputes. He also handles pro bono asylum cases and brings a strategic, client-focused approach to every matter.
Thomas J. Umberg
(949) 679-0052- [email protected]
Thomas J. Umberg has extensive trial experience in both federal and state courts and has been selected as a “Best Lawyer” for the prestigious publication “The Best Lawyers in America®” in commercial litigation for 12 consecutive years.
Chris Wang
- (949) 679-0052
- [email protected]
Chris Wang is an associate at Umberg/Zipser, focusing on complex commercial litigation and bringing experience from his time at Gibson, Dunn & Crutcher, where he handled high-stakes litigation and investigations. He earned his J.D. magna cum laude from UC Irvine School of Law, where he held editorial and clinical roles and received multiple scholarships. He also holds a B.A. in International Affairs with a minor in Sociocultural Anthropology from George Washington University, graduating cum laude.
Dean J. Zipser
(949) 679-0052- [email protected]
Dean J. Zipser is a recognized leader in the Orange County legal community, having served as President of the Orange County Bar Association (OCBA) along with many other professional leadership positions.
NEWS and EVENTS
Umberg/Zipser in the Community
Umberg/Zipser Recognized Among Daily Journal’s 2026 Top Boutiques in California
Umberg/Zipser LLP is pleased to announce that the firm has been named one of the Daily Journal’s 2026 Top Boutiques in California. The recognition highlights the firm’s work and the dedication of the firm’s attorneys and team to providing sophisticated legal counsel with the responsiveness, collaboration, and personal attention of a boutique practice. We’re proud of the firm we’ve built and grateful to our
Todd Smith Examines Imputed Conflicts in Orange County Lawyer
Umberg/Zipser partner Todd Smith authored “When Lawyers Move: Imputed Conflicts and the Two Roads Out,” published in the October 2026 issue of Orange County Lawyer. The article examines a recent California appellate decision addressing conflicts of interest arising from lateral attorney hires, including ethical screening requirements and available options for firms seeking to avoid disqualification. Click here to read the article
Umberg/Zipser Co-Founder Dean Zipser to Retire from Firm and Join JAMS as Mediator
IRVINE, Calif., October 5, 2026 — Umberg/Zipser LLP announced today that co-founder Dean J. Zipser will retire from the firm at the end of 2026 and begin the next chapter of his career as a neutral with JAMS. Zipser co-founded Umberg/Zipser in 2014, building the firm around a commitment to exceptional legal work, collaboration, professional integrity, client service, and giving back to the profession
Umberg/Zipser Secures $2.9 Million Judgment for 24 Investors in Pro Bono Fraud Case
IRVINE, Calif., September 14, 2026 – Umberg/Zipser LLP secured a $2,896,550 judgment on behalf of 24 individuals in a pro bono fraud and breach of contract case involving nearly 70 written investment agreements. In Cervantes et al. v. Verdin d/b/a Achilles Investments LLC, the plaintiffs alleged that defendant Jonathan Verdin induced them to enter into written contracts by promising returns of more than twice,
Enforcing Third-Party Discovery Subpoenas in Arbitration
In “Enforcing Third-Party Discovery Subpoenas in Arbitration,” U/Z attorney Chris Wang examines recent developments under the California Arbitration Act and Federal Arbitration Act and what they may mean for third-party discovery in arbitration. The article was originally published in Volume XXVII No. 2 of the ABTL OC Report.
Umberg/Zipser Recognized as a 2026 Civic 50 Orange County Honoree for the Eighth Consecutive Year
Umberg/Zipser LLP is proud to announce that it has been recognized as a 2026 Civic 50 Orange County Honoree, marking the eighth consecutive year the firm has received this distinction. Presented by OneOC in partnership with Points of Light, the Civic 50 Orange County recognizes companies that demonstrate an outstanding commitment to corporate social responsibility and community engagement. At Umberg/Zipser, giving back is in
CAREERS
At Umberg/Zipser LLP, it’s the quality of our people that makes our firm and work environment rewarding and unique. We are proud to have repeatedly been recognized by our team as one of Orange County’s “Best Places to Work.”
If you are an exceptional attorney, who thrives on delivering top-notch client service, and enjoys practicing law in a strong team culture, we invite you to contact us to learn more about how we can support your career growth.
Umberg/Zipser is also proud to have created a work environment that promotes and honors diversity and we are an equal opportunity employer. We look forward to hearing from you soon.