Denise Tsai is a litigator with an emphasis on securities and financial services litigation, complex commercial disputes, and internal corporate and government investigations. Ms. Tsai has defended numerous corporations and their officers and directors against claims of breaches of fiduciary duty, fraud, and accounting issues, in matters before the Securities and Exchange Commission (“SEC”), the Department of Justice (“DOJ”), and other regulators, as well as in civil and criminal litigation. She has experience handling all phases of civil litigation including dispositive motion practice and preparing witnesses for depositions and trial, and has worked on winning trial and appellate teams. Ms. Tsai has also advised companies and secured successful resolutions in government investigations by the SEC, DOJ, the Financial Industry Regulatory Authority, and other federal and state regulators. Ms. Tsai also maintains a robust pro bono practice, particularly in assisting immigrants through the US naturalization process and in civil rights litigation.

In 2020, Ms. Tsai served as a Special Assistant Attorney General in the Massachusetts Attorney General’s Office’s Trial Division, where she engaged in all aspects of civil litigation, including successful arguments before the Supreme Judicial Court and the Massachusetts Appeals Court.

Ms. Tsai co-teaches the seminar, “Asian Americans and the Law,” at Harvard Law School. 

Prior to joining the firm, Ms. Tsai clerked for the Honorable Kiyo A. Matsumoto of the US District Court for the Eastern District of New York. During law school, she was a student lawyer in the Immigrants' Rights Clinic at Stanford Law School, and a research assistant for Stanford Law School Professor David F. Engstrom in the area of qui tam litigation. She also served as a consultant to the Royal Government of Bhutan through Stanford Law School’s Bhutan Law and Policy Project. 

Prior to law school, Ms. Tsai was an honors paralegal at the Antitrust Division of the US Department of Justice in Washington DC, where she worked on a variety of merger investigations.


  • Represents several African-American organizations and individuals in a successful challenge to Georgia’s enacted state maps under Section 2 of the Voting Rights Act in the Northern District of Georgia, and pending appeal in US Court of Appeals for the Eleventh Circuit Court
  • Defended a public company’s board members in shareholder class action alleging breaches of fiduciary duty arising from going-private transaction in Delaware Chancery Court
  • Defended Special Purpose Acquisition Company (“SPAC”) in SEC securities fraud and DOJ criminal investigations
  • Secured trial victory and injunction in favor of T-Mobile in high-stakes contract dispute against Cox Communications in Delaware Chancery Court
  • Secured judgment on all counts for Harvard University in a case challenging the use of race in its undergraduate admissions process following three-week federal bench trial
  • Conducted internal investigation of telecommunications expense management company relating to accounting and revenue recognition practices, and defended company in related SEC investigation as well as shareholder open market fraud class action in Delaware Chancery Court
  • Defended a major Boston-based financial institution in a cross-border investigation relating to allegations of fraud, including before the SEC and DOJ
  • Represented various public corporations in the consumer products and services sector in internal and government investigations as well as shareholder class action and derivative lawsuits relating to accounting practices, stock drops, and corporate governance and controls


  • Named to Boston Magazine’s Top Lawyers list in the area of securities law (2023).
  • Selected for inclusion in Best Lawyers: Ones to Watch for securities litigation (2021–2024), white-collar criminal defense (2022–2024) and labor and commercial litigation (2024).

Insights & News


  • Education

    • JD, Stanford Law School, 2013

      Submissions Chair, Stanford Journal of International Law
    • BA, Political Science, Amherst College, 2007

      magna cum laude, with Distinction in English Phi Beta Kappa
  • Admissions

    • Massachusetts

    • US Court of Appeals for the First Circuit

    • US Court of Appeals for the Eleventh Circuit

  • Clerkships

    • The Hon. Kiyo A. Matsumoto, US District Court for the Eastern District of New York, 2013 - 2014



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