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Daniel M. Sullivan



Daniel Sullivan’s practice focuses on complex commercial litigation, appeals, and transnational litigation. Daniel was named a New York Law Journal Rising Star in 2015, has been named to Benchmark Litigation’s 40 & Under Hot List since 2017 and its Future Star List since 2018, and was named to the New York Law Journal’s inaugural Trailblazer list in 2019 and to the National Law Journal’s Elite Boutique Trailblazer list in 2020.

Before joining Holwell Shuster & Goldberg in April of 2014, Daniel was a litigation associate in the New York office of Gibson, Dunn & Crutcher LLP. 

Before entering private practice in November of 2010, Daniel served as a law clerk to the Honorable Antonin Scalia of the United States Supreme Court during October Term 2009, and before that to the Honorable Diarmuid F. O’Scannlain of the United States Court of Appeals for the Ninth Circuit during the 2008-2009 term.

Notable Cases

Notable Cases

  • Clients in a variety of appeals in state and federal court, including:
    • A primary insurance carrier and an excess carrier in a successful appeal in New York’s First Department in an insurance coverage dispute arising out of the SEC’s late-trading and market-timing investigation of Bear Stearns in the mid-2000s. HSG obtained a reversal of the trial court’s grant of summary judgment to the successors of Bear Stearns, convincing the Appellate Division to hold that, as a matter of law, $140 million in SEC disgorgement imposed on Bear Stearns was an uninsured penalty. The case is pending in New York’s Court of Appeals.
    • Individual in appeal in the Second Circuit from insider-trading conviction arising out of alleged tipping of Medicare reimbursement rules. The case raises novel issues of the meaning and scope of the wire-fraud and conversion-of-government-property statutes. Although the Second Circuit ruled against our client, the defendants petitioned the Supreme Court for certiorari, and the Supreme Court granted the petition, vacated the judgment of the Second Circuit, and remanded for further consideration in light of the Court’s decision in Kelly v. United States, 590 U.S. ___ (2020). Proceedings on remand to the Second Circuit are pending.
    • Insurer in a Second Circuit appeal that raises the question of whether the parties agreed to a binding arbitration agreement or an optional ADR clause conditioned on future agreement. Appeal is pending.
    • Caterpillar, Inc., in a successful appeal in New York’s First Department from an adverse verdict in asbestos litigation. Vacating the verdict and dismissing the complaint against Caterpillar, the First Department refined the law of specific causation in asbestos cases, holding that it is insufficient to measure exposure to the products of a group of defendants because the degree of exposure must be proven from the defendant’s products specifically.
    • Senator Ted Cruz in ballot eligibility challenges in New York in connection with the 2016 Republican Presidential Primary. Daniel successfully defended dismissal of a challenge on appeal in New York State court and, subsequently, obtained dismissal of a second challenge and successfully defended that dismissal on appeal. Daniel represented the Senator in his individual capacity and not on behalf of HSG.
    • Auto parts manufacturer Hilite International in a successful post-trial appeal in the Federal Circuit of patent claims involving variable valve timing in automobile cam phasers. Obtained reversal of trial judgment against client on the grounds that the patent at issue was invalid.
    • Wife in New York’s First Department in appeal from high-profile, high-dollar divorce trial involving valuation and disposition of art collection worth hundreds of millions of dollars. Obtained stay pending appeal of portion of adverse trial judgment directing sale of the art collection. 
    • Westchester County in proceedings in the Second Circuit and S.D.N.Y. regarding legal and constitutional issues arising out of the settlement of a qui tam action against the County.
  • Various affiliates of Chubb in nationwide litigation against manufacturers and distributors of opioids, and national pharmacy chains that sold opioids, over insurance coverage for over 3,000 lawsuits brought by governmental entities across the country. HSG is national trial counsel to Chubb in opioid coverage litigation. 
  • Minority partners, and management of an auto-loan servicing business in Puerto Rico, in a contentious partnership dispute with the majority partner, a prominent New York hedge fund. Daniel led an HSG team that took over the case in the middle of discovery, promptly initiated new litigation in federal court in Puerto Rico, won several key motions in the pending New York action, and fought what became a sprawling litigation across five proceedings. The case ultimately settled favorably.
  • TerraForm Power, an owner and operator of solar and wind power sites, in various litigations, including a shareholder derivative lawsuit brought in Delaware Chancery regarding a private placement of stock with TerraForm’s then-controlling shareholder, and a breach-of-contract arbitration in New Jersey against a counterparty over payments for solar projects on the rooftops of Macy’s store locations. Both lawsuits are pending.
  • Trustees in RMBS putback litigation in New York state and federal court, handling motion practice, document and deposition discovery, expert discovery, trial preparation, and appellate Four federal and two state-court cases Daniel was involved in settled favorably in the middle of discovery. In another federal-court case in which Daniel was involved, HSG was hired after an adverse pre-trial ruling; HSG shifted strategy in further pre-trial motions and engaged in trial preparation, and the case settled favorably on the eve of trial.
  • Former directors and an officer of a publicly traded technology services company in a putative securities fraud class After HSG filed a motion to dismiss, Plaintiffs dropped Securities Exchange Act claims against our clients and, after HSG filed a motion to dismiss an amended complaint, Plaintiffs dropped all claims against our clients. In a related proceeding in the company’s bankruptcy case, in which breach-of-fiduciary-duty claims were alleged against the former directors, the bankruptcy court granted HSG’s motion to dismiss.
  • Governor Andrew Cuomo in constitutional challenge, launched at the end of 2018, to New York statute establishing a commission on prosecutorial misconduct.
  • A Belgian flooring company and its S. affiliate sued for patent infringement. HSG moved to dismiss the complaint or stay the litigation pending a related arbitral proceeding in Switzerland regarding the validity of a sublicense, which had been granted to HSG’s clients, to use the patents-in-suit. The district court granted HSG’s motion to stay and the plaintiff eventually agreed to dismiss the action.
  • Dow Jones in putative consumer class action alleging various common law and New York statutory claims, successfully moving for summary judgment and defending victory on appeal.
  • Clients in a wide variety of industries and circumstances regarding appellate, constitutional, and other legal issues arising in potential or pending state and federal litigation. Recent examples include advising an owner and operator of renewable energy assets on a portfolio of contract and shareholder litigation, advising a State government considering potential challenges to prospective legislation, assisting a hedge fund regarding Supreme Court litigation related to the fund’s interests, evaluating RICO claims arising out of the Flint water crisis, and advising a real estate developer regarding the constitutionality of state taxation laws.
  • Pro bono clients in immigration. For example, Daniel represented a legal permanent resident under an order of removal in a Ninth Circuit appeal raising novel issues of the retroactive application of statutes. After Daniel filed his opening brief, the Government agreed to a favorable remand. Daniel also represented a legal permanent resident in an Eleventh Circuit appeal raising whether the BIA must defer to a state-court clarification of a prior sentencing record. Once again, after Daniel filed his opening brief, the Government agreed to a favorable remand. Daniel then successfully moved to dismiss the removal proceeding before the BIA.

News and Writings



  • "Bristol-Myers Squibb v. Superior Court: Practical Implications and Doctrinal Conundrums," Bloomberg BNA Class Action Litigation Report (August 14, 2017) (co-author)
  • "Statutory Interpretation and the Morrison Presumption Against Extraterritoriality," Bloomberg Law Week (March 23, 2017) (co- author)
  • "A Gentleman of the Law: A Tribute to Judge Diarmuid F. O’Scannlain" National Review Online (January 5, 2017) (co-author)
  • "International Aspects of S. Litigation," American Bar Association (co-author of chapter on personal jurisdiction (2017))
  • "Microsoft United States Addresses the Presumption Against Extraterritoriality in the Digital Context" The Cross-Border Cut (December 2016), Holwell Shuster & Goldberg LLP Transnational Litigation and Arbitration Briefing (co-author)
  • "BG Group PLC Republic Of Argentina: The Supreme Court Applies Domestic and Commercial Arbitration Principles to the Review of Investment Treaty Arbitration Awards," Mealey’s International Arbitration Report (2014)
  • "U.S. Supreme Court Holds that Presumption Against Extraterritoriality Applies to the Alien Tort Statute," Gibson, Dunn & Crutcher LLP Client Alert (co-author, 2013)
  • "U.S. Supreme Court Clarifies Limitations Period for Federal Enforcement Actions," Gibson, Dunn & Crutcher LLP Client Alert (co-author, 2013)
  • "Truly Original," The Daily (2011), A Review of Living Originalism, by Jack Balkin
  • "Big Boys and Chinese Walls," 175 University of Chicago Law Review 533 (2008)
Photo of Daniel M. Sullivan


  • Hon. Antonin Scalia, Supreme Court of the United States, 2009-2010
  • Hon. Diarmuid F. O’Scannlain, U.S. Court of Appeals for the Ninth Circuit, 2008-2009


The University of Chicago Law School (J.D., high honors, 2008; Order of the Coif; Appellate Advocacy Clinic, Representation in the U.S. Court of Appeals for the Seventh Circuit; Staff Member, The University of Chicago Law Review)

The University of Chicago (B.A., History (honors) and Fundamentals (honors), 2004; John Olin Fellow; Student Marshall; Phi Beta Kappa; Karafiol Prize for best B.A. essay in European History)

Bar and Court Admissions

  • New York
  • Supreme Court of the United States
  • U.S. Court of Appeals, Federal Circuit
  • U.S. Court of Appeals, First Circuit
  • U.S. Court of Appeals, Second Circuit
  • U.S. Court of Appeals, Fifth Circuit
  • U.S. Court of Appeals, Seventh Circuit
  • U.S. Court of Appeals, Ninth Circuit
  • U.S. Court of Appeals, Eleventh Circuit
  • U.S. District Court, Eastern District of New York
  • U.S. District Court, Southern District of New York
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