Kieran Gostin consistently achieves successful results for clients in complex litigation and high-stakes trials, having represented clients in several significant antitrust matters. He was a member of the trial team that secured a groundbreaking victory for Microsoft, defeating the FTC’s efforts to enjoin its $68.7 billion acquisition of Activision Blizzard and winning the second-biggest merger trial in American history. Kieran handled multiple witnesses in the five-day bench trial, following which Judge Jacqueline Scott Corley denied the FTC’s motion for preliminary injunction, finding that the FTC failed to make its case that the acquisition would substantially lessen competition in the gaming industry. Kieran currently serves as co-lead counsel for Visa in connection with an action brought by the DOJ alleging that Visa has illegally monopolized the debit card industry. For these and other representations, Chambers and Partners has recognized Kieran as an “Up and Coming” antitrust attorney.
Kieran has also represented clients in major consumer class actions and products liability trials. Among his many trial victories was the first jury verdict for Bayer in its nationwide Roundup litigation. Kieran was also a member of the trial team in a multi-state class action that accused Bayer of using misleading claims to market One A Day multivitamins. Kieran was responsible for arguing legal issues at the trial, as well as cross-examining one of the class representatives. The jury returned a complete defense verdict in less than two hours.
Kieran has received “Rising Star” awards from the National Law Journal and Law360, and was named a “Future Star” by Benchmark Litigation. Lawdragon has named him to its “500 Leading Litigators in America” list and he has been recommended by Legal 500 for “Sports.”
Before joining the firm, Kieran was a trial attorney in the Federal Programs Branch of the U.S. Department of Justice, where he was the lead attorney in matters challenging the legality of executive agency action, including cases involving challenges to federal healthcare and national security programs.
Kieran’s other notable representations include:
Member of trial team that won complete defense verdicts in first two bellwether trials in In re: Xarelto (Rivaroxaban) Products Liability Litigation, a nationwide federal MDL proceeding involving over 20,000 lawsuits related to the blood-thinner Xarelto. Also, member of trial team that won JNOV in Hartman v. Janssen, the first state-court bellwether trial involving Xarelto in Philadelphia’s Court of Common Pleas.
Represented Forest Laboratories in In re Namenda Direct Purchaser Antitrust Litigation, a certified antitrust class action in the Southern District of New York involving a groundbreaking treatment for dementia in Alzheimer’s patients. Plaintiffs claimed that Forest made an anticompetitive “reverse payment” to settle a generic drug manufacturer’s challenge to Namenda, and that Forest unlawfully tried to effectuate a “hard switch” between a twice-daily and once-daily version of Namenda. Plaintiffs claimed approximately $21 billion in trebled damages; the case settled the night before trial for less than 5% of that amount.
Updated Sep 2025