Sheila A.G. Armbrust

SHEILA ARMBRUST has spent her career at the intersection of technology, life sciences, and high-stakes litigation. She represents a variety of clients, including software and AI developers, autonomous vehicle makers, medical device manufacturers, biopharma manufacturers, and fintech companies. As a former federal prosecutor, Sheila diligently guides clients through complex legal challenges which include internal and government-facing investigations, civil litigation in federal court, and compliance programs.

“Sheila is a fierce litigator and very personable, a rare combination that makes her incredibly valuable to clients.”
Chambers USA 2025

Leveraging her experience as a former Assistant U.S. Attorney for the Northern District of California, Sheila brings a strategic advantage to the defense of companies and executives facing inquiries from the U.S. Department of Justice (DOJ), Securities and Exchange Commission (SEC), Federal Trade Commission (FTC), and state attorneys general. She has persuaded the DOJ and SEC to close investigations without enforcement action in multiple matters, and she brings that same insider fluency to the other side of the table, representing victims in support of federal criminal prosecutions. Sheila also regularly advises boards and special committees navigating the intersection of government scrutiny and corporate governance.

Sheila has served as lead counsel in major federal litigation across the same industries, representing plaintiffs and defendants in bet-the-company litigation. She represented senior executives of one of the world’s most prominent technology platforms in a high-profile dispute following a major acquisition, which settled favorably. She has served as trial counsel in a federal RICO class action in which she successfully moved to decertify a class of hundreds of thousands of potential plaintiffs, and as lead counsel for multiple financial services companies in defeating claims on motions to dismiss. Sheila is adept at both trial advocacy and recognizing when a negotiated resolution better serves her client’s interests.

While at the U.S. Attorney’s office, Sheila handled sophisticated white-collar crime, including securities fraud, wire fraud, trade secret theft, computer fraud, and violations of the Food, Drug, and Cosmetic Act.

Sheila has been recognized by Chambers USA for Litigation: White-Collar Crime & Government Investigations in California (2024–2025). In the 2025 edition, clients have praised her service and legal prowess, calling her “someone who masters the facts of her cases and is able to translate them to prosecutors in a way that is extremely impressive. She really gets the job done — she is an exceptional attorney,” and that she is an “excellent trial lawyer.”

• Lead counsel for money services business defending against federal and state law claims involving customer data.
• Representing an American biopharmaceuticals company and several executives in connection with DOJ and SEC investigations related to the development a cutting edge drug. Successfully convinced the DOJ to drop the investigation. 
• Represented an artificial intelligence company in DOJ and SEC investigations. Successfully closed the investigation without enforcement action from both government agencies.
• Representing an autonomous vehicle company in crisis management planning in the aftermath of DOJ and SEC investigations. 
• Representing the Special Committee of the board of an online video game company in a DOJ and state AG investigation.
• Representing fintech and financial services companies in DOJ investigations in connection with PPP loans. Successfully convinced the DOJ to decline intervention. 
• Representing life sciences company in a DOJ investigation involving allegations of off-label promotion and kickbacks.
• Trial counsel for a telecommunications client in federal RICO litigation who successfully moved to decertify a class of hundreds of thousands of potential litigants.
• Representing a leading public company retailer in internal and government investigations relating to management of supply chain issues.
• Representing a trade association in a highly publicized investigation by the California Attorney General involving allegations of fraud in connection with claims about the recyclability of plastics.
• Represented a blockchain technology company in responding to DOJ investigations.
• Represented a cybersecurity company in a trade secret misappropriation investigation.
• Represented the independent directors of the board of a medical device company in DOJ investigation.
• Represented a pharmaceutical manufacturer in lengthy criminal and civil investigations involving allegations of off-label promotion and kickbacks.

• San Francisco Inclusion Committee Partner Chair
• San Francisco leader, SidleyWomen

• Obtained declination of DOJ investigation and voluntary dismissal of civil lawsuit for a not-for-profit scientific institution in an FCA matter.
• Obtained compassionate release from federal prison sentence for client facing more than 16 years for a first-time criminal offense.
• Obtained a state court order to seal arrest record for client who was factually innocent of crimes for which she was arrested but not charged.
• Obtained asylum for woman and her minor children from Mexico.