Seth Rosenstein-600

Seth M. Rosenstein


Seth Rosenstein is a partner in the Litigation, Controlled Substances and Regulatory Law and Residential Real Estate departments. He has significant experience representing clients in the negotiation and litigation of commercial and civil disputes in state and federal courts, as well as before American Arbitration Association and Financial Industry Regulatory Authority arbitration panels. Seth has practiced in all aspects of securities class action litigation before state and federal courts throughout the United States and serves as a FINRA Dispute Resolution Services Arbitrator. He also regularly handles residential real estate transactions in New Jersey and New York.

Seth represents a wide range of clients, from large commercial property owners to individuals, across a broad spectrum of industries, including real estate, financial services, construction, cannabis, manufacturing, trucking and more in connection with contract disputes, torts, regulatory issues, construction and real estate issues, shareholder disputes, and various other business-related disputes. He has developed a particular expertise prosecuting and defending alleged violations of consumer protection and related statutes. While recognized as an aggressive and focused litigator, Seth’s focus is on positioning each action to achieve each client’s desired outcome in the most efficient manner.

Immediately prior to joining Ansell Grimm & Aaron, Seth practiced in the Manhattan office of a national litigation firm. Prior to bar admission, he served as an intern with the New York State Department of Financial Services, the Kings County District Attorney’s Office and the Federal Deposit Insurance Corporation.

Representative Matters

  • Served as outside legal counsel to a Fortune 500 financial services company in arbitration actions brought before FINRA arbitration panels
  • Contributed to a successful appeal securing stay of all administrative proceedings relating to applications for marijuana alternative treatment centers in New Jersey following improper disqualification of certain applicants
  • Defended construction and design defect claims brought by a large cooperative building complex in New York City against an engineering firm
  • Successfully vacated an eight-year-old default judgment awarded to a state administrative agency, reversed seizure of funds and combatted litigation abuses undertaken by state’s outside counsel
  • Obtained temporary restraints on behalf of a corporate client in a dispute involving a hemp cultivation and harvesting facility
  • Secured possession of a luxury home in Westchester County after years of litigation and compelled highly favorable settlement, resulting in settlement windfall and strong profit after selling the home to a third-party purchaser
  • Obtained substantial judgment for minor child of a wealthy property developer and owner, ensuring that over $1 million in improperly withheld funds were paid into a trust established for the minor child’s benefit
  • Aggressively and successfully defended numerous actions filed by “testers” alleging violations of the Americans with Disabilities Act and related state statutes, resulting in prompt dismissals of all claims in exchange for negligible consideration
  • Represented FINRA-registered financial professional in action against national broker-dealer related to incorrect and misleading public disclosures, resulting in filing of amended Form U5 — correcting an injustice that falsely besmirched client’s reputation
  • Secured summary judgment as to all causes of action and subsequent denial of reconsideration application in complex litigation against real estate seller alleging consumer fraud and breach of contract, among other claims.
  • Litigated action on behalf of local businesses after a national energy supplier substantially overbilled and breached contract for provision of electricity.  After limited discovery, vigorous prosecution resulted in a substantial monetary payment to the local businesses
  • Represented local property developer in securing declaratory relief pertaining to a shopping center and certain master deed restrictions, resulting in an order permitting the construction and operation of a well-known gas station and convenience store at the subject property


  • New Jersey Bar
  • New York Bar
  • Pennsylvania Bar
  • United States District Court for the District of New Jersey
  • United States District Court for the Southern District of New York
  • United States District Court for the Eastern District of New York
  • United States District Court for the Eastern District of Pennsylvania
  • United States Court of Appeals for the Second Circuit
  • United States Court of Appeals for the Third Circuit

Associations & Memberships

  • Bergen County Bar Association
  • Westchester County Bar Association


New York, NY
Woodland Park, NJ

Support Staff

Assistant: Lymari Ramos

Practice Areas


Benjamin N. Cardozo School of Law, Yeshiva University, J.D., 2015

American University, B.A., 2011