A former law clerk to Justice Antonin Scalia of the U.S. Supreme Court and to Judge Diarmuid F. O’Scannlain of the Ninth Circuit, Daniel Sullivan is a true generalist, whose practice ranges across trial litigation and appeals over numerous subject matters, postures, and aspects of the profession. Described by clients as “bright, incisive, deep, and relentless,” Dan has led or played a key role in cases in forums around the country, as well as leading arbitrations before JAMS and AAA.
A leader of HSG’s appellate practice, he is currently spearheading or has argued appeals in the Second, Seventh, and Eleventh Circuits, as well as New York’s First and Third Departments and Court of Appeals, the Supreme Courts of Nevada and West Virginia, and the Arkansas Court of Appeals. Dan currently represents opt-out investors in an appeal to the Nevada Supreme Court addressing, for the first time, the standards for direct shareholder actions under Nevada corporate law. He recently argued an appeal in the West Virginia Supreme Court raising novel questions regarding when an anti-suit injunction is appropriate. He obtained partial reversal from the Second Circuit of a portion of a judgment confirming an arbitration award against his client, TIG Insurance Company; an order from the U.S. Supreme Court vacating a Second Circuit decision in an appeal with significant implications for insider trading prosecutions, ultimately leading to a complete vacatur of the conviction against his client; reversal of a jury verdict in New York’s First Department in an appeal establishing an important precedent in asbestos cases; and a reversal in the Federal Circuit of a jury trial judgment in a patent-infringement case against an auto-parts manufacturer.
He also has had a leading role in trial-level commercial litigation, including representing Chubb in approximately 20 insurance coverage actions nationwide arising out of the national opioid epidemic, managing RMBS putback cases covering billions of dollars in loans, representing AmTrust in a dispute with its managing agent, securities fraud matters, partnership breakdowns, earnout disputes, and other business litigation. Dan was also appointed to serve as plaintiffs’ liaison counsel in a high-profile multi-district litigation alleging that pregnant women’s prenatal use of acetaminophen, such as Tylenol, caused autism and ADHD in their children.
Dan recently joined the advisory board of the Institute of Judicial Administration at NYU School of Law, a prestigious group of judges and appellate advocates recognized for their contributions to the justice system and has been a regular panelist for the New York Federal Bar Council’s annual Supreme Court preview program since 2018. He was named a Rising Star and a Trailblazer by the New York Law Journal, an Elite Boutique Trailblazer by The National Law Journal, and a Litigation Star by Benchmark Litigation.
Key Practice Areas: Appellate; Business & Commercial; Civil Litigation; Class Action; Constitutional; Intellectual Property; Securities; Trials
Year Joined Firm: 2014
Education: The University of Chicago Law School (J.D.), Order of the Coif; The University of Chicago (B.A.)
Updated Sep 2024
