Chelsea Cosillos is a litigator who focuses her practice on complex commercial matters in federal and state courts and arbitration proceedings, including class action and appellate cases. Across a variety of industries, she has represented clients in disputes involving ERISA, antitrust, fraud, breach of contract, product liability, breach of fiduciary duty, and securities claims.
Chelsea also maintains an active pro bono practice, with an emphasis on immigration and criminal appeal matters.
- Representing a major health insurer in a variety of matters, including cases involving ERISA, fraud, breach of contract, and antitrust claims.
- Obtained complete victory on behalf of a major health insurer against multiple hospitals alleging improper reimbursement of certain out-of-network emergency services claims; successfully narrowed the hospitals’ causes of actions through multiple rounds of motions to dismiss and defeated the hospitals’ remaining statutory claim at summary judgment on the eve of an anticipated two-week federal jury trial in the Southern District of Florida.
- Represented a major health insurer in lawsuit against large for-profit health system for the health systems’ misrepresentations and breach of contract; after four-week arbitration and post-hearing briefing, case settled favorably in a global resolution of other disputes and open business issues.
- Represented a home textile manufacturer in defense of putative class actions alleging product mislabeling, including successful defense to challenges in multiple courts to class-wide settlement.*
*Matter handled prior to joining McDermott
- Empire State Counsel Program Honoree, 2018
Harvard Law School, JD, 2018
Arizona State University, BS, summa cum laude, 2013