Michael J. Sullivan

Michael J. Sullivan


Michael J. Sullivan is an Associate in the Sills Cummis & Gross Litigation Practice Group. His practice focuses on complex commercial litigation and white collar and securities litigation matters. He represents corporate and individual clients in commercial matters involving allegations of fraud, breach of contract, breach of fiduciary duty and similar wrongdoing, as well as in labor disputes, environmental-related litigation and lawsuits involving claims of sexual harassment. He has also advised clients in connection with federal and state criminal and regulatory investigations, state administrative proceedings, enforcement proceedings and internal investigations. Mr. Sullivan has represented clients in trials in both state and federal courts, as well as in mediations.

Mr. Sullivan is also a member of the Firm’s Cannabis Industry Practice Group and a member of the New York State Bar Association’s Committee on Cannabis Law.

Prior to joining the Firm, Mr. Sullivan was an associate at Dechert LLP in New York.

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Representative Matters

  • Represent an individual in litigation involving the substantial estate of the individual’s deceased spouse against claims of alleged undue influence in connection with the drafting of decedent’s will and various inter vivos transfers among bank accounts.
  • Represent a concrete, sand and crushed gravel company in litigation involving the contamination, remediation and excavation of a parcel of land in New Jersey.
  • Represent the owner of industrial property in New Jersey in a dispute involving claims of breach of contract, business torts and statutory violations over the failed attempt by an international developer to purchase the property.
  • Represent a leading swimming pool chemical manufacturer in a labor dispute stemming from a lockout of the manufacturer’s employees.
  • Represent an advertising agency and its employees in a lawsuit involving claims of sexual harassment, retaliation and related tort claims.
  • Represented an international auto parts manufacturer in connection with investigations of alleged defects by the National Highway Traffic Safety Administration, Congress, the Department of Justice and other government entities, and in related civil litigation.
  • Represented a private equity firm in related lawsuits brought in New York state court alleging breach of contract, fraud, breach of fiduciary duty and other claims arising out of disputes over the management of residential properties in Pennsylvania and Indiana.
  • Represented a bond trader in an SEC investigation regarding alleged misrepresentations and market manipulation.
  • Successfully defended an international express mail delivery company in a month-long jury trial in New York state court against multi-million dollar breach of contract claims brought by 31 businesses. Has also represented this client at the trial and appellate level in several matters pending in state and federal courts involving breach of contract and business tort claims.
  • Successfully defended a Mexican entertainment company in a bench trial in federal court on breach of contract claims by affiliates of an international movie theatre chain arising out of the purchase of a group of Mexican cinemas.
  • Represented a lawyer at a mutual fund in an SEC investigation regarding alleged conflict of interest violations.
  • Successfully earned dismissal of breach of contract and business tort claims against a multinational bank in litigation brought by a Spanish energy company arising out of Argentina’s expropriation of the energy company’s ownership in an Argentine oil company. 

Court Admissions

U.S. District Court, District of New Jersey, 2010
U.S. District Court, Southern District of New York, 2011
U.S. District Court, Eastern District of New York, 2011


Member, New Jersey State Bar Association
Member, New York State Bar Association
–    Member, Committee on Cannabis Law