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Tammy L. Roy

Tammy L. Roy


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Cahill Gordon & Reindel LLP
32 Old Slip
New York, NY 10005



  • George Washington University Law School, J.D., 2001, High Honors
  • University of Pennsylvania, B.A., 1998, cum laude


  • New York
  • Massachusetts

Tammy Roy, member of Cahill's Executive Committee and Co-Chair of the firm's Commercial Litigation practice group, represents global corporations and financial institutions in complex commercial and securities litigation in federal and state courts throughout the country and in connection with regulatory investigations and enforcement matters.

Tammy has served as a lead counsel in the defense of one of the world’s leading credit rating agencies in connection with civil lawsuits and government inquiries around the United States and abroad, arising out of its ratings of structured finance securities, sovereigns, public finance, and bond insurers.

"Tammy is intelligent, practical and really takes the time to understand not only the issue at hand but also to understand its impact on the business." – Chambers USA

Tammy has been praised by Chambers as a “partner who is the full picture,” "pragmatic in terms of how she thinks about the business perspective and needs," and “great on her feet in court and a real talent.” Clients note that she is "super detail-oriented and great at handling thorny issues in the details." In addition to being ranked as a leading litigator by Chambers USA, Tammy has also been recognized by The Legal 500, named as a Litigation Star by Benchmark Litigation, and was featured among the 2020 Notable Women in Law by Crain’s New York Business.

In 2024, Tammy was named as a Thomson Reuters Stand-out Lawyer. She was recognized as a 2023 General Litigation Trailblazer by The National Law Journal, and in 2022 as one of The American Lawyer’s Litigators of the Week, for her role in the winning defense of Credit Suisse in a jury trial in the Southern District of New York involving claims of a 16-bank global conspiracy to fix prices in the foreign exchange market in violation of the federal antitrust laws. Tammy was shortlisted for the Women in Business Law Awards Americas, Financial Regulation Lawyer of the Year for both 2022 and 2023 and is listed in Lawdragon’s 500 Leading Litigators in America guide. Earlier in her career, Tammy was named to Benchmark Litigation’s “Under 40 Hot list”.

Tammy joined Cahill in 2001, and was elected to the partnership in 2010. She serves as Chair of the firm’s Women’s Initiatives Committee.

  • Won dismissals, affirmed on appeal, of multiple putative securities class actions against S&P alleging that it was subject to liability as an underwriter under Section 11 of the Securities Act of 1933 in connection with its ratings of residential mortgage-backed securities.
  • Won dismissal, affirmed on appeal, of a putative securities class action against S&P and certain of its former officers alleging violations of the federal securities laws in connection with alleged misstatements and omissions in S&P’s SEC filings and other public statements.
  • Defended a leading global insurer in a class action in state court in Alabama alleging fraud claims in connection with the earlier settlement of multiple securities class actions.
  • Prevailed on behalf of a public company in obtaining the dismissal with prejudice of a putative securities class action filed after the company announced its intent to restate certain of its prior financial statements.
  • Represented a major financial institution in a bench trial in federal court in connection with claims relating to its role as lead underwriter for an issuance of pension obligation bonds.
  • Has represented companies in a variety of industries in defense of purported class action lawsuits involving alleged violations of the federal securities laws.
  • Has successfully defended multiple companies in arbitration trials seeking hundreds of millions of dollars in damages. 
  • Successfully defended numerous actions (including state and federal class actions and several arbitrations) that alleged an employee benefit plan offered by a securities retail brokerage firm operated to effect an illegal forfeiture of wages.