Biography
Ellen Leonida is an accomplished trial lawyer with more than two decades of experience in white collar criminal defense, internal and government investigations, and complex commercial litigation. A Fellow of the American College of Trial Lawyers—one of the premier professional organizations in North America that recognizes the top trial lawyers in the United States and Canada for their exceptional advocacy, professionalism, and integrity—Ellen has tried more than 80 jury cases to verdict in state and federal courts.
Ellen advises both individuals and companies in a wide range of criminal matters, including trade secret theft, bribery, money laundering, and fraud. She also guides clients through internal investigations and government inquiries, offering practical counsel to minimize exposure and resolve matters efficiently. A nationally recognized expert in forensic evidence, Ellen frequently lectures on topics including DNA, digital forensics, and trial strategy.
In addition to her criminal defense practice, Ellen represents clients in complex civil litigation, including disputes involving breach of contract, trade secret misappropriation, and unfair business practices. She also handles probate litigation matters such as will and trust contests, fiduciary duty claims, and disputes over estate administration.
In addition to her criminal defense and civil litigation practices, Ellen is deeply committed to public service. Her pro bono work has focused on protecting civil rights and advancing access to justice, including representing classes of incarcerated individuals and immigrants challenging systemic government misconduct, and defending free speech and opposing censorship in public institutions.
Before joining Sideman & Bancroft, Ellen led the impact litigation and white collar groups at a boutique litigation firm in San Francisco. Earlier in her career, she served as a Federal Public Defender in the Northern District of California.
Experience
• Secured a jury verdict and $21 million judgment, plus attorneys’ fees, for a consumer packaged goods start-up against a manufacturer in a breach of contract dispute
• Secured a permanent injunction for a biotech start-up after its co-founder misappropriated trade secrets to form a competing company
• Represented library patrons fighting censorship in a Texas public library; obtained an injunction requiring the county to restore censored books
• Represented a defendant charged with trafficking counterfeit merchandise; obtained acquittal on all counts after jury trial
• Represented a defendant charged with murder; obtained acquittal on all counts after jury trial
• Represented a company in a false claims investigation; obtained declination of prosecution
• Represented a defendant charged with extortion; obtained deferred prosecution
Professional Involvement
A 2023, 2024, and 2025 California Super Lawyer, Ms. Leonida has been widely recognized for her excellence in civil and criminal litigation. She received the Fr. Cuchulain Moriarty Award from the Lawyers’ Committee for Civil Rights of the San Francisco Bay Area (2024) and was twice named in The American Lawyer’s “Litigator of the Week – Shout Outs” (2023). In 2025, she was inducted into the American College of Trial Lawyers.
Appointed by the judges of the Northern District of California, Ms. Leonida serves as the Criminal Justice Act Panel Attorney Representative for the district. She is also a member of the Bar Association of San Francisco’s Criminal Justice Task Force and serves on the Executive Committee of the Northern District of California Federal Bar Association.
Ms. Leonida currently teaches as an adjunct professor at the University of San Francisco School of Law and has previously taught at the University of California, Berkeley School of Law. She also served as a Lawyer Representative for the Northern District of California Judicial Conference from 2016 to 2018.
Education
- University of California, Santa Cruz B.A. 1993
- University of California, Berkeley J.D. 1996
Admissions
- California
Awards
