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Dennis Patrick O'Brien

Criminal defense Attorney at Huntington, NY

5.0   3 reviews
  • Licensed for 20 years
    State NY
    Acquired 2004
    Currently Registered No misconduct found

We have not found any instances of professional misconduct for this lawyer.

About Dennis

Learn Dennis’s areas of practice.

Since 2006, Dennis O’Brien has been practicing as a founding parting at O'Brien Law Group, LLC. Mr. O’Brien is dedicated to protecting the rights of the accused in Long Island, New York. Prior to working at the firm, Attorney O’Brien worker as a prosecutor for four years, handling criminal cases from traffic offenses, misdemeanors to serious felony offenses. With former prosecution experience, Dennis is uniquely qualified to defend your charges. He understands both sides of the criminal justice system and he knows how to build a solid and compelling defense case for court. With Long Island criminal defense attorney Dennis O’Brien by your side, your rights can be protected against the prosecution and you can fight to have your charges reduced or dropped altogether. Mr. O’Brien is actively involved in the community and is also a member in several notable Associations including the Board of Directors of the Criminal Courts Bar Association and the Board of Directors of the Criminal Courts Bar Foundation charity. 


O'Brien Law Group, LLC
7 High Street, Suite 205
Huntington, NY, 11743

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5.0 / 5.0
  3 customer reviews
5 Star
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1 Star
Posted by anonymous | January 30, 2019
This review is from a potential client who consulted with this attorney.
| Consulted Attorney
The best attorney to have in your corner!
Dennis O'Brien went above and beyond for me. I am more secure now with him in my corner. I would recommend everyone to see him.
Posted by Bill | March 14, 2018
This review is from a person who hired this attorney.
| Hired Attorney
Wonderful Attorney
Dennis O’Brien handled a complicated legal matter for my daughter and we both couldn’t be happier with his diligence, his total competence, his zeal, his compassion and his determination to do the right thing for his client. He kept us well informed at every stage of the representation and took all the time that was necessary for us to understand the steps he was taking, the options we had, and the predictable outcome of each option. While no case is perfect, he was perfect for our case and we will be forever grateful for his effort and the results he achieved.
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Posted by Ty | December 3, 2014
Professional Attorney
Dennis O'brien is a well, well above average Lawywer with his endless knowledge of the legal system and ability to execute the best possible outcomes for his clients. As having expierence with him, I would in a moment contact him with any future legal obligations. He is expierenced, smart, friendly and above all makes sure all options are expanded in the interest of his clients. Would recommend to a friend.
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  • Retainer Always
Payment methods
Cash, Check, Credit Card


AVVO RATING 8.1 (Excellent)

Work Experience

  • Adjunct Assistant Professor
  • St. John's University
  • 2000 - Present
  • Attorney
  • O'Brien Law Group, LLC
  • 1999 - Present


  • Brooklyn Law School
  • JD - Juris Doctor
  • N/A
  • St. John's University
  • MA - Masters
  • N/A
  • St. John's University
  • BA
  • N/A


  • Nassau County Bar Association
  • Member
  • N/A
  • Suffolk County Criminal Bar Association
  • Member
  • N/A
  • New York State Bar Association
  • Member
  • N/A
  • Criminal Courts Bar Association of Nassau County
  • Member
  • N/A
View all associations

Languages Spoken

  • English

Attorney endorsements

Received (4)
Given (0)
Endorse Dennis
Criminal defense Attorney | Nov 19
Relationship: Opposing Counsel on matter
"As a former prosecutor, I opposed Dennis on a number of cases and tried a complicated Dwi trial against him. Dennis is one of the most professional and knowledgeable defense attorneys I have encountered. I endorse this lawyer."
Criminal defense Attorney | May 18
Relationship: Worked together on matter
"I strongly endorse Dennis O'brien. I have know him for years and have seen his legal work first hand. He is one of the finest legal minds I have ever come across. You will not go wrong hiring him."
Criminal defense Attorney | Jan 30
Relationship: Fellow lawyer in community
"Dennis is an excellent attorney. He is works incredibly hard for all of his clients. He is so knowledgeable that other attorneys frequently call him to ask questions about their case. You will be in terrific hands with Dennis as your attorney."
Criminal defense Attorney | Oct 14
Relationship: Fellow lawyer in community
"I have known Mr. O'Brien for many years and I have had the opportunity to work with him on several criminal cases. His knowledge of the law and trial skills have always impressed me. He is a diligent and conscientious attorney that always fights hard for his clients. I strongly endorse Mr. O'Brien."
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Avvo Contributions

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Huntington Criminal defense Lawyer Dennis Patrick O'Brien
Dennis Patrick O'Brien
Criminal defense Attorney
Huntington, NY
Licensed for 20 years