Lev Dassin’s practice focuses on representing companies, boards of directors, and executives in government investigations, complex commercial litigation, and crisis management.

He often represents clients in matters involving multiple investigations in the U.S. and around the world, as well as related civil litigation, involving various forms of alleged misconduct, including financial fraud, corrupt payments, and antitrust offenses. He also frequently represents clients in private commercial disputes, including antitrust, contract, securities, mass tort, and intellectual property litigation.

Before returning to private practice in 2009, Lev served as Acting U.S. Attorney for the Southern District of New York. In that capacity, he was responsible for all criminal and civil litigation in the district on behalf of the United States and supervised more than 220 Assistant U.S. Attorneys. Lev previously served as Deputy United States Attorney, the second in command of the office, and as Chief of the Criminal Division, in charge of all of the criminal prosecutions and investigations in the district.

Earlier in his career, Lev served as an Assistant U.S. Attorney. At that time, he prosecuted a wide range of cases involving terrorist acts, racketeering violations, money laundering and other white-collar crimes. Lev was a lead prosecutor in the investigation and prosecution of Ramzi Yousef, the mastermind of the 1993 terrorist bombing of the World Trade Center. In recognition of his work on that case, Lev was honored with the Attorney General’s Award for Distinguished Service. He also received the Attorney General’s Award for Exceptional Service for his role in the investigation and prosecution of four other defendants for their participation in the 1993 World Trade Center bombing.

Lev has taught trial practice at Columbia Law School since 1999.

Lev joined the firm as a partner in 2009.

Notable Experience

  • AIG in connection with the resolution of various criminal and regulatory investigations and related civil litigation in Italy, U.K., and Argentina involving the sale of insurance products in those regions by a former AIG subsidiary.

  • Alpha Natural Resources in various matters, including in reaching a comprehensive settlement  with the U.S. Department of Justice and U.S. Mine Safety & Health Administration resolving potential corporate criminal and civil liability related to the tragic explosion at Upper Big Branch Mine on April 5, 2010, that killed 29 miners.

  • Citigroup in various matters, including in connection with various government investigations and related civil litigation involving financial benchmarks, including LIBOR, foreign exchange trading, and ISDAFIX.

  • Commerzbank AG in various matters, including its resolution of various U.S. criminal and regulatory enforcement investigations involving compliance with U.S. anti-money laundering requirements.

  • National Amusements Inc. (NAI), Shari Redstone, and Sumner Redstone in Delaware Chancery Court litigation against CBS Corporation and certain members of its Board of Directors concerning CBS’s attempt to dilute NAI’s voting control of CBS, ending in favorable resolution rescinding dilutive stock dividend and dismissal of all claims.

  • Pfizer in various matters, including as trial counsel with respect to product liability litigation related to a developmental anti-inflammatory and separately with respect to the antidiabetic drug.

  • Sanofi U.S. in winning summary judgment in a multibillion-dollar monopolization lawsuit brought by a competitor challenging Sanofi U.S.’s loyalty discounts for its anticoagulant drug, Lovenox, and successfully defending the decision on appeal to the Third Circuit.

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Selected Activities

Lecturer in Law, Columbia Law School


Second Circuit: Criminal Fraud Statutes Do Not Require Prosecutors to Show that Tippers in Insider-Trading Cases Received a ‘Personal Benefit,’” (co-author) Cleary Gottlieb Alert Memo, January 13, 2020.

UK Serious Fraud Office Publishes Corporate Co-Operation Guidance,” (co-author) Cleary Gottlieb Alert Memo, September 24, 2019.

New Scrutiny for NDAs in Sexual Harassment Matters,” (co-author) Harvard Law School Forum on Corporate Governance and Financial Regulation, May 16, 2019; republished by Law360, June 24, 2019

Bill Proposal—Corporate Executives Criminally Accountable for Negligent Conduct,” (co-author) Harvard Law School Forum on Corporate Governance and Financial Regulation, April 18, 2019

“Representing Corporations in United States Attorney’s Office and DOJ Investigations,” (co-author) Defending Corporations and Individuals in Government Investigations (Thomson Reuters, 4th Edition 2017-18).

“Pre-Charge Presentations to a U.S. Attorney’s Office and the Department of Justice” (co-author) in West’s Defending Corporations and Individuals in Government Investigations (2010-11).