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40 & Under List

Litigation Star

Practice area:


A former clerk for Justice Antonin Scalia and for Judge Diarmuid F. O’Scannlain on the Ninth Circuit, Daniel Sullivan has been recognized as a Rising Star (2015) and a Trailblazer (2020) by the New York Law Journal, and an Elite Boutique Trailblazer (2020) by The National Law Journal. He has also been named to Benchmark Litigation’s 40 & Under since 2017, and was recognized as a Litigation Star in 2021.

Dan is a leader of Holwell Shuster & Goldberg’s appellate practice. He recently obtained 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. In January 2021, he won an order from the U.S. Supreme Court vacating a Second Circuit decision in an appeal with significant implications for insider trading prosecutions. He is presently representing TIG Insurance Company in an appeal in the Second Circuit addressing the interpretation of conditions precedent to arbitration. That appeal has been consolidated with another in the same case raising whether the district court’s decision should have been vacated because the judge held stock in TIG’s adversary when he ruled in its favor—a high profile issue in the wake of a Wall Street Journal exposé on judicial stockholdings that cited HSG’s motion to vacate. Dan is also representing 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.

Individually, Dan represented Senator Ted Cruz in ballot eligibility challenges in New York State and federal court in connection with the 2016 Republican Presidential Primary election, prevailing in every case. 

Simultaneously, he has a leading role in trial-level commercial litigation. This includes managing massive RMBS putback cases covering billions of dollars in loans, managing insurance coverage disputes in multiple fora arising out of the opioid crisis—where Dan recently successfully argued a summary judgment motion for Chubb in the Northern District of California—securities fraud matters, and other business litigation. Recently, Dan came into a case, after an adverse ruling, on behalf of minority partners and management of a Puerto Rican auto-loan servicing business in a contentious partnership dispute with a prominent hedge fund. After initiating several new fronts in the litigation and prevailing in several key motions, the case settled favorably. 

Dan is also an active member of HSG’s pro bono practice, especially in immigration appeals. In two recent cases in federal circuit courts, he represented legal permanent residents under orders of removal in appeals raising novel legal questions. In both, after Dan filed his opening brief, the government agreed to a favorable remand. 


Key Practice Areas:

  • Appellate
  • Business & Commercial
  • Civil Litigation
  • Class Action
  • Constitutional
  • Intellectual Property
  • Securities

Year Joined Firm:


  • The University of Chicago Law School (J.D., Order of the Coif);
  • The University of Chicago (B.A.)


Updated Aug 2022