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Overview

Cassidy Mandelbaum focuses her litigation practice on commercial disputes and intellectual property matters, including trademark and copyright litigation in Florida’s federal and state courts. Her work spans discovery strategy and disputes, protective order practice, and motion drafting from filing through resolution. Cassidy has prepared and filed trademark applications before the USPTO, guiding clients through the application, examination, and registration process, including 2(d) likelihood of confusion office action responses and specimen advisory. Clients value working with Cassidy for her accessibility and clear communication. She stays reachable throughout a matter and explains legal strategy in plain, straightforward terms. She works to give clients a sense of comfort, security, and control over their matter.

Cassidy earned her Juris Doctor from Washington University in St. Louis School of Law in May 2025. As a law student, she was a member of the Global Studies Law Review, received the William M. Pomerantz Award for her performance in the INTA Saul Lefkowitz Trademark Moot Court Competition, and worked in the First Amendment Clinic representing clients in speech-rights matters.

Before joining Jimerson Birr, Cassidy was a Legal Intern at the U.S. Attorney’s Office for the Middle District of Florida, Jacksonville Division, where she gained trial experience from filing through sentencing across the criminal litigation process.

A Jacksonville-area native from Fernandina Beach, Cassidy is a triple Gator: she holds a bachelor’s degree in marketing, a bachelor’s degree in Tourism, Hospitality, Event and Sport Management, a minor in real estate, and an MBA in Marketing, all from the University of Florida. She returned to Northeast Florida after law school to practice in her home community.

Outside the office, Cassidy is an artist and children’s book author.

  • Bar and Court Admissions

    • The Florida Bar
    • U.S. District Court, Middle District of Florida
    • U.S. District Court, Southern District of Florida
  • Education

    • Washington University in St. Louis School of Law, Juris Doctor
    • University of Florida, Master of Business Administration in Marketing
    • University of Florida, Bachelor of Science in Marketing; Bachelor of Science in Tourism, Hospitality, Event and Sport Management; Real Estate Minor; Honors
  • Representative Matters

    • Advised a trademark owner on enforcement against multiple defendants.
    • Asserted Lanham Act, trade secret, contract, and unfair trade practices claims in a pre-suit demand on behalf of a business against a former employee’s competing venture.
    • Drafted motions to suspend proceedings and extend time in a TTAB cancellation proceeding paired with a federal trademark action in the Southern District of Florida, on behalf of the registrant.
    • Defended a company and its officers in a federal intellectual property infringement action in the Middle District of Florida.
    • Overcame a USPTO Section 2(d) likelihood-of-confusion refusal citing four marks and secured registration for a consumer packaged goods brand.
    • Prepared trademark clearance opinion letters and advised on registration strategy, including for marks with foreign-language meanings.
    • Represented a defendant in a design patent infringement action in the Southern District of Florida with a negotiated resolution.
    • Successfully defended against a pre-suit copyright infringement demand.

    PRIOR RESULTS DO NOT GUARANTEE A SIMILAR OUTCOME

Industries

Cassidy Mandelbaum
Banking and Financial Services Learn more
Cassidy Mandelbaum
Communications & Media Learn more
Cassidy Mandelbaum
Manufacturing and Distribution Learn more
Cassidy Mandelbaum
Transportation and Logistics Learn more
Cassidy Mandelbaum
Professional Services Learn more

News

Jimerson Birr Welcomes Six New Attorneys Strengthening Firm’s Litigation and Transactional Practices
  1. News
Jimerson Birr Welcomes Six New Attorneys Strengthening Firm’s Litigation and Transactional Practices

Jacksonville, FL – Jimerson Birr is proud to announce the return of six new attorneys: Olivia A. “Liv” King, Cassidy M. Mandelbaum,…

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Best Firms badge for Jimerson Birr, P.A., [2027] edition by Best Lawyers
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Law Firm 500, Fastest Growing Law Firms in the United States
Florida Trend Legal Elite
National Veteran-Owned Business Association, Certified Veteran's Business Enterprise
GrowFL Florida Companies to Watch, 2025
Top Workplaces, 2025
U.S. Department of Defense SkillBridge Program
Jacksonville Business Journal Best Places to Work, 2020
Best Lawyers
Gator100, University of Florida
Best Places to Work, 2021
Martindale-Hubbell AV Preeminent Peer Review Rated
Jacksonville Magazine's Companies with Heart, 2026
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