Long Island Criminal Defense Attorney

Dennis O'Brien

Dennis O'Brien is a founding partner of Prime & O'Brien, LLP and has been a member of the firm since 2006. Prior to his time with the firm, Mr. O'Brien was an Assistant District Attorney with the Nassau County District Attorney's Office. Serving as a prosecutor from 2002 until 2006, Mr. O'Brien handled all kinds of criminal matters from the most minor traffic infractions to the most serious violent felonies.

Mr. O'Brien is an active member of the local community, serving on the Board of Directors of the Criminal Courts Bar Association since 2008. As a member of the Board, Mr. O'Brien has directed its Legal Action Committee and has directly authored an Amicus Curiae brief on behalf of the organization. Additionally, Mr. O'Brien was Chair of the 2011 Criminal Courts Golf Outing and is a member of the Board of Directors of the Criminal Courts Bar Foundation charity.

In addition to his volunteer work with the Bar Association, Mr. O'Brien has been an Adjunct Assistant Professor at St. John's University since 2000. Teaching courses in International Law, Comparative Law and Western Political Thought, Mr. O'Brien has spent the last decade preparing undergraduate students for the rigors of law school.

Mr. O'Brien received his J.D. from Brooklyn Law School, M.A. from St. John's University and B.A. from St. John's University. He is also a graduate of Chaminade High School. Mr. O'Brien is a member of the Nassau, Suffolk and New York State Bar Associations and the Criminal Courts Bar Association of Nassau County, and is admitted to practice in New York State and the Eastern and Southern Districts of New York.

Education

  • Juris Doctorate (J.D.) - Brooklyn Law School
  • Master of Arts (M.A.) - St. John's University
  • Bachelor of Arts (B.A.) - St. John's University

Bar Admissions

  • New York State
  • Eastern District of New York
  • Southern District of New York

Associations

  • New York State Bar Association
  • Nassau County Bar Association
  • Suffolk County Bar Association
  • Criminal Courts Bar Association of Nassau County

Awards & Accolades

  • Member, Board of Directors - Criminal Courts Bar Association
  • Chair - 2011 Criminal Courts Golf Outing
  • Member, Board of Directors - Criminal Courts Bar Foundation (Charity)
  • Adjunct Assistant Professor - St. John's University, 2000 - Present
    • Courses Taught: International Law, Comparative Law, and Western Political Thought
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