Sean M. Sullivan

Complex Business Trials and Appeals

• Appellate Brief and Oral Argument Victory (Published): Hay v. Marinkovich, 108 Cal.App.5th 707 (2025) – Secured a published appellate decision representing a former business owner on appeal from a case in which she sued a former employee under California’s Comprehensive Computer Data Access and Fraud Act for copying her hard drive without her permission. Although the defendant escaped liability in the underlying trial, the trial court denied his motion seeking more than $300,000 in attorney’s fees. On appeal, the Fourth District Court of Appeal announced the now-precedential standard governing attorney fee awards to prevailing defendants under the Act, and affirmed the order in the client’s favor denying defendant recovery of any of his attorneys’ fees.
• Breach of Fiduciary Duty Jury Trial: Served as lead trial counsel for a software company in a complex jury trial against one of its own directors for breach of fiduciary duty, securing a jury verdict entirely in the client’s favor.
• Breach of Contract and Fraud Jury Trial: Served as lead trial counsel defending a property owner against claims of financial elder abuse, breach of contract, and fraud based an alleged agreement to sell a home to the plaintiff, the client’s close relative. Obtained a complete and unanimous defense verdict following a week-long jury trial.
• Shareholder Derivative Bench Trial: Served as lead trial counsel for company in a San Diego Superior Court bench trial (shareholder derivative action) involving breach of fiduciary duty claims brought by dissident shareholders, resulting in a judgment in favor of the management defendants.

Intellectual Property and Trade Secrets

• Copyright Infringement Trial (Upheld on Appeal): Trial counsel for a software company in a federal copyright infringement lawsuit. A unanimous jury found no infringement and declared the client the owner of the disputed software copyright, a victory the Ninth Circuit Court of Appeals affirmed.
• Partnership, Trade Secrets and Copyright Dispute: Represented former principals of an architecture firm in litigation with their ex-partners involving claims of copyright infringement, theft of trade secrets, and unfair competition. Pursued counterclaims for breach of fiduciary duty and other misconduct, resulting in a favorable settlement before trial.
• Copyright Act/VARA Claim: Represented large construction company sued under the Visual Artists Rights Act (VARA) and the Copyright Act (17 U.S.C. § 106A), claiming the construction company destroyed an artist’s sculptural work of art during its construction activities in violation of the Act.
• Trade Secrets Dispute (Plaintiff): Represented employer in trade secret litigation against former employees, and obtained direct evidence showing defendants used smartphone to photograph, text and email sensitive, confidential and proprietary customer information to the client’s competitor in violation of California’s Uniform Trade Secret Act.
• Trade Secrets Disputes (Defense): Represented employees accused by employers of unlawfully taking or misusing confidential and proprietary customer information amounting to trade secrets when departing their jobs and/or working for competitors.
• Patent Infringement Trial (Medical Device): Second-chair on trial team defending a medical device distributor in a federal patent infringement case, which concluded with a favorable post-trial settlement for the client.
• Patent Infringement Defense (Software Industry): Defended a software developer/marketer against a patent infringement claim, resolving the case with only a nominal nuisance-value settlement.

Class Actions and Consumer Litigation

• Consumer Finance Class Action (Overdraft Fees): Successfully defended a financial institution in a class action involving ATM overdraft fees, defeating motion for class certification, winning summary judgment on most claims, and obtaining voluntary dismissal of the entire remaining single-plaintiff case without any payment by the client to plaintiff.
• Consumer Class Actions: Represented companies in defending numerous class actions asserting claims under various California and federal consumer statutes asserting unfair competition claims, including with regards to product labelling, product contents, manufacturing processes, membership or subscription autorenewal practices, and website term disclosures. Obtained numerous settlements on favorable terms, including final court orders approving class settlements.
• Environmental Toxic Tort Class Action: Defended a national aerospace manufacturer in a complex toxic tort class action alleging nuisance and trespass due to vapor intrusion of volatile organic compounds, with plaintiffs seeking medical monitoring and other remedies. Final class settlement approved.
• Groundwater Contamination Lawsuit: Defended the same aerospace manufacturer in a related toxic tort action brought by property owners who alleged property damage from groundwater contamination beneath their properties.

Business Counseling and Risk Management

• Preventative Litigation Counseling: Counsel businesses across industries on strategies to minimize litigation risk and handle disputes proactively, leveraging extensive trial experience to resolve issues before they escalate to lawsuits.
• Corporate Governance Advice: Advise corporate boards and executives on fiduciary duties, partnership agreements, bylaws and operating agreements, and governance practices to prevent internal disputes, ensure compliance and minimize or mitigate risks.

Other Significant Representations and Experience

• Maritime Litigation: Extensive experience in maritime law, including representing clients in cases involving serious personal injuries aboard seagoing vessels (admiralty and Jones Act matters).
• Injury Claims Defense: Defended organizer of off-road races in numerous matters related to claims for injuries by participants and spectators.
• Diverse Industry Experience: Has represented clients in a wide array of industries—from aerospace, software, automotive racing, and biotechnology to craft brewing, entertainment, and banking—in high-stakes litigation and dispute resolution.