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.
Darian McMillan
- (949) 988-7187
- [email protected]
Darian McMillan is an associate at Umberg Zipser, where she practices intellectual property law. Darian advises clients on trademark prosecution and enforcement, copyright, unfair competition, and licensing.
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
Umberg/Zipser Delivers Trial Victory for Startup Founder in Ownership Dispute
Umberg/Zipser LLP secured a significant trial victory in Orange County Superior Court on behalf of a startup founder who was wrongfully removed from his company by his co-founders as the business approached its first major contract. The matter was tried by partners Phil Kaplan and Ethan Feng. Following a bench trial, the court awarded the client the full value of his remaining salary under
The creator economy is booming—but so are the risks.
In this latest article in the Orange County Lawyer, Carole Reagan and Darian McMillan unpack the legal pitfalls of influencer marketing and outline how brands and creators can protect themselves through thoughtful compliance and smart contracts. Read the full article here
Umberg/Zipser LLP Recognized in Chambers Spotlight California 2026 for Intellectual Property and Litigation
IRVINE, Calif. — Umberg/Zipser LLP has been recognized in the Chambers Spotlight California 2026 guide, earning distinction in both Intellectual Property and Litigation: General Commercial. This marks the firm’s second consecutive year recognized for its Intellectual Property practice and its first year included for Litigation. The Chambers Spotlight guide highlights outstanding small to mid-sized firms that deliver sophisticated legal services and serve as strong
Umberg/Zipser LLP Welcomes Jeremy G. Suiter as Partner
IRVINE, Calif., March 23, 2026 — Umberg/Zipser LLP is pleased to announce that Jeremy G. Suiter has joined the firm as a partner in its litigation practice. Suiter brings more than two decades of experience representing businesses and individuals in complex business litigation, including shareholder and partnership conflicts, fraud and business tort claims, trade secret matters, and contract disputes. His practice focuses particularly on disputes
Mei Tsang Featured in Super Lawyers Southern California
We’re proud to share that Umberg/Zipser partner Mei Tsang is featured in the 2026 Super Lawyers Southern California issue (see p. 38). In the profile, Mei reflects on her journey from Xi’an to leadership in Orange County’s legal community, her passion for intellectual property law, and her commitment to mentoring, service, and expanding access to justice. The article highlights her thoughtful, strategic approach to helping
2026 Super Lawyers Honorees
Umberg/Zipser LLP is pleased to share that seven firm partners have been named to the 2026 Southern California Super Lawyers list, an honor awarded to no more than five percent of attorneys statewide. The firm also celebrates Dean Zipser’s continued distinction as one of the Top 50 Orange County Lawyers, marking his eighth consecutive year receiving this recognition. The following Umberg/Zipser attorneys have earned
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.