PARTNER
DENNIS P. O'BRIEN received his J.D. from Brooklyn Law School, and a B.A. and M.A. from St. John's University. He began his legal career in 2002 as an Assistant District Attorney with the Nassau County District Attorney's Office. After leaving the District Attorney's Office, Mr. O'Brien was in private practice for 14 years before joining Frazer & Feldman. During his time at the DA's office and in private practice, Mr. O'Brien developed significant trial experience. He has served as a 3214-hearing officer for dozens of hearings.
Since joining the firm, Mr. O'Brien has focused on all aspects of employee and student discipline and general litigation. He became a Partner in 2025. He has handled numerous complex proceedings pursuant to Education Law 3020(a), Civil Service Law § 75, and Education Law § 3214. In addition, Mr. O'Brien has served as lead counsel in federal and state litigation. He has handled civil actions in both federal and state court and administrative proceedings, such as appeals to the Commissioner of Education. Most notably, Mr. O'Brien served as lead counsel and appellate advocate in North Shore Cent. Sch. Dist. v. Glen Cove City Sch. Dist., in which the firm secured a landmark decision in the Appellate Division, Second Department, firmly establishing a three-year statute of limitations for litigation seeking to recover disputed tax revenue from a bisected property.
Mr. O'Brien assists school district clients with regulatory compliance. In this role, he has headed investigations into violations of Title IX, the Dignity for All Students Act, and individual school district harassment policies. He regularly advises clients on revisions and updates to board policies to ensure compliance with relevant state and federal law.
He has served as lead negotiator for multiple collective bargaining negotiations. His experience includes negotiating contracts between school districts and superintendents, assistant superintendents, teachers, teachers' aides, buildings and grounds, clerical, bus drivers and nurses. He also attends school board meetings, advising clients on proper meeting procedures.
Mr. O'Brien has been a panelist and lecturer at many school law conferences. He has presented various topics within the realm of employee/student discipline and general litigation. His presentations include: “Deal or no Deal” Disciplinary Proceedings in Cyberspace”; “Bridge Over Troubled Water: Student Discipline and Investigation”; “Striking a Balance: Where Mental Health and Restorative Practices Intersect with Student Disciplinary Proceedings”; “Me!–Navigating Employee Mental Health Concerns”; “Navigating the Conflict Between State Laws Prohibiting the Use of Tribal Names and Symbols and the Current Administration's Interpretation of Title VI”; “The Bare Necessities: Mandatory and new Requirements for Codes of Conduct”; and “Immunization Litigation Roundtable” (forthcoming May 2026).
Mr. O'Brien also has regularly published articles on school-related topics. Recent publications include:
· December 2025 “Preparing for a Chilly Reception: When ICE Officers Come to School” The Nassau Lawyer, Nassau County Bar Association
· February 2026 “Public Schools and Off-Campus Student Speech: The Second Circuit's New Standards” The Nassau Lawyer, Nassau County Bar Association
· March 2026 “Court to Determine Whether NYS Must Reinstate Religious Exemptions” On Board, New York State School Boards Association
Mr. O'Brien is a full Adjunct Professor at St. John's University, and has been teaching constitutional law, comparative law, and judicial process and procedure for the past twenty-six years. He also continues to present his academic writing at colloquia and conferences throughout the country. Mr. O'Brien is admitted to practice in New York, the Southern District of New York, the Eastern District of New York and the Supreme Court of the United States.