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.
Mei Tsang
- (949) 679-0052
- [email protected]
Mei has an international intellectual property practice focused on helping clients formulate their IP strategy, and shepherding their IP through various business cycles to achieve their business goals worldwide.
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
Martin Fessenmaier Recognized as an IAM Strategy 300 Global Leader for the Fourth Consecutive Year
Umberg/Zipser congratulates Martin Fessenmaier on being named an IAM Strategy 300 Global Leader for the fourth consecutive year. The IAM Strategy 300 recognizes leading professionals from around the world for their strategic insight into patents and intellectual property. Martin’s continued recognition reflects his thoughtful approach to helping clients develop, protect, and maximize the value of their innovation. Congratulations, Martin, on this well-deserved honor.
Five Umberg/Zipser Attorneys Recognized in the 2027 Southern California Super Lawyers® List
Umberg/Zipser LLP is proud to announce that five attorneys have been selected for inclusion in the 2027 Southern California Super Lawyers® list, recognizing attorneys who have attained a high degree of peer recognition and professional achievement. Dean J. Zipser — Business Litigation (recognized for the 23rd year) Mark A. Finkelstein — Intellectual Property Litigation (recognized for the 18th year) Scott B. Garner — Professional
Scott Garner and Amy Lesperance Author “A New Era of Civility?” for Orange County Lawyer
In the August 2026 issue of Orange County Lawyer, Umberg/Zipser partner Scott Garner and associate Amy Lesperance explore the growing emphasis on civility in the legal profession. The article examines recent developments from the California Supreme Court and State Bar, explains why civility is fully compatible with zealous advocacy, and discusses the practical benefits of professionalism for clients, courts, and attorneys alike. Drawing on
Umberg/Zipser Secures Jury Verdict Eliminating Punitive Damages Exposure for MGA Entertainment
Umberg/Zipser Secures Jury Verdict Eliminating Punitive Damages Exposure for MGA Entertainment (July 2, 2026) Umberg/Zipser congratulates Mark Finkelstein and Ellen Kim, who, together with co-counsel at McKool Smith, secured a unanimous federal jury verdict finding that MGA Entertainment and its CEO, Isaac Larian, are not liable for $125 million in punitive damages in the company’s long-running litigation involving rapper T.I. Harris and MGA’s L.O.L.
Mark Finkelstein Named to Orange Coast Magazine’s Best of O.C. Legal 2026 for Intellectual Property Litigation
Congratulations to Umberg/Zipser LLP Managing Partner Mark Finkelstein on his selection to Orange Coast Magazine’s Best of O.C. Legal 2026 for Intellectual Property Litigation. This year’s selection process combined attorney peer feedback, community input, independent research, and analysis guided by a former Super Lawyers publisher to recognize attorneys for excellence in their practice areas. Umberg/Zipser is proud of Mark’s recognition, which reflects the firm’s longstanding commitment
Umberg/Zipser LLP Sponsors OCBA Charitable Fund Annual Judge Kenneth Lae Charity Golf Scramble in Orange County
Umberg/Zipser LLP is proud to continue our sponsorship of the Orange County Bar Association Charitable Fund’s Annual Judge Kenneth Lae Charity Golf Scramble. This event reflects the legal community’s shared commitment to service and access to justice. The OCBA Charitable Fund supports law-related organizations throughout Orange County that strengthen our justice system and expand access to legal services for those in need. This year, Mei
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.