Attorney Mark J. O’Brien - Tampa, FL
Federal Criminal Defense Lawyers in Tampa, FL
511 West Bay Street Suite 330 Tampa, FL 33606
- Free Consultation
- 2 Super Lawyers®
- 19 Attorney Ratings
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17
Years
Experience
Featured Review
"You come to a lawyer scared and likely confused about what's going to happen next. How serious is this accusation and is there the possibility of being exonerated? Mark did an amazing job of calming our fears with facts and details and a plan of..." "You come to a lawyer scared and likely confused about what's going to happen next. How serious is this accusation and is there the possibility of being exonerated? Mark did an amazing job of calming our fears with facts and details and a plan of action. he was very honest about the areas of "concern" and the things he could do to paint things in a favorable light. He then thoroughly defended and protected us. He investigated the rules, identified the gray areas, and showed how we didn't have any intent to break them. He then came up with a plan of action to get the charged dropped with a way to maintain good favor with the authority in question. No one wants to be in this situation but Mark (and his ENTIRE staff) made it the most tolerable experience possible and eventually ensure the absolute best outcome imaginable."
Tampa Federal Criminal Defense Law Firm
Updated: 05/19/2026
Reviews
Customer Reviews for Attorney Mark J. O’Brien
Read reviews that mention:
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Verified ClientHired Law firm 2023-2024You come to a lawyer scared and likely confused about what's going to happen next. How serious is this accusation and is there the possibility of being exonerated? Mark did an amazing job of calming our fears with facts and details and a plan of action. he was very honest about the areas of "concern" and the things he could do to paint things in a favorable light. He then thoroughly defended and protected us. He investigated the rules, identified the gray areas, and showed how we didn't have any intent to break them. He then came up with a plan of action to get the charged dropped with a way to maintain good favor with the authority in question. No one wants to be in this situation but Mark (and his ENTIRE staff) made it the most tolerable experience possible and eventually ensure the absolute best outcome imaginable.
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Verified ClientHired Law firm 2024-2026Words cannot express how much I highly recommend Mark and his team. From the first time we met him, his professionalism and concern for our family put us at ease. The process, the cost and what they do were explained to us. There were no surprises. Nothing was left for us to figure out and I like that a lot. They answered any question or concern that we had at anytime. They were with us every step of the way. On one occasion my family member needed medical assistance. Mark made sure it got done. After waiting for the jail to do something for over two weeks, one call to him, then from him and he got it done in less than 24hrs. That is just a small example of why you need someone like him on your side. Even afterwards, they are still here. If we need something, if our family member needs them, literally anything. They will still be there. It is as if once they begin helping your family, you become THEIR family. Mark, Jeanette, Aaron and Tucker, our family appreciate you so much. We would have been lost without you all. Thank you for being such a blessing to us and Great at what you do.
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Verified ClientHired Law firm 2020-2026Everybody at the O’Brien Hatfield law firm has been amazing! They are very professional, knowledgeable, and friendly. The whole team has been there for me from the moment I got charged all the way to the end. I got the BEST possible outcome. I strongly recommend you contact them immediately if you ever are in trouble with the law. Thank you for all of your help!
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Verified ClientHired Law firm 2025HIGHLY RECOMMEND. I have a fairly lengthy record and I was falsely advised of impersonating a police officer. Jeanette contacted me immediately and was like a pitbull beginning to end. My attorney, Sheryl, was a very quiet BEAST. Polite, polished, focused and no nonsense. She didn’t beat around the bush but she did her job and O’Brien Hatfield came through helping me walk out a free man today! As someone who has done a fair share of time and been in those terrifying courtrooms, this law firm demonstrated why it’s important to have a great lawyer and team representing you!
Areas of Practice
- Federal Criminal Defense
- White collar crimes
- Sex crimes
- Child pornography
- Embezzlement
- Drug Violations
- Tax evasion
- Money laundering
- Immigration-related offenses
- Murder
- Felon in possession of a firearm
- Treason
Litigation: 100%
Firm Information
Overview
Attorney Mark J. O’Brien is a criminal defense practice focused on nationwide federal criminal defense, as well as statewide criminal defense and criminal appeals.
Attorney Mark J. O’Brien is the founder and lead attorney. He represents clients in federal criminal courts across the United States and has built a strong reputation among federal judges and prosecutors for his skill and advocacy. A former Miami prosecutor, Mark brings over twenty-five years of experience to his practice and remains deeply committed to each case he handles, approaching every client with the same dedication and energy as when he began his career.
Attorney Victoria E. Hatfield serves as a key member of the practice, focusing on state and county criminal defense. She has secured numerous not guilty verdicts and has successfully argued motions to dismiss and suppress across a wide range of cases. Known for her tenacity and courtroom presence, Victoria is a strong and reliable advocate for her clients.
Olivia M. Goodman leads the firm’s criminal appellate work. She has handled over a hundred appeals, achieving consistent success in challenging convictions. Olivia takes a collaborative approach with clients and is recognized for her thorough analysis and strategic advocacy in appellate matters.
Attorney Mark J. O’Brien is supported by a dedicated team of paralegals, legal assistants, and private investigators, with the resources and commitment necessary to thoroughly investigate and aggressively defend every case.
Awards and Honors
Super Lawyers® Selectees
Attorney Mark J. O’Brien selected for a Super Lawyers® list
- Hatfield, Victoria E. On a Super Lawyers® List
- O'Brien, Mark J. On a Super Lawyers® List
Languages
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Spanish
Published Works
Articles
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Are You Committing a Federal Crime by Playing Fantasy Sports?, 2015
Millions of people play daily fantasy sports, but is it legal? Criminal defense attorney Mark J. O'Brien is concerned that federal prosecutors may begin targeting it as a white collar crime.
Attorneys
Staff
- Jeanette Hevel, Legal Assistant, 8132634758
- Kiersten Richter, Legal Assistant
- Hana Shitama, Legal Assistant
- Denise Montero, Legal Assistant
Staff
- Jeanette Hevel, Legal Assistant, 8132634758
- Kiersten Richter, Legal Assistant
- Hana Shitama, Legal Assistant
- Denise Montero, Legal Assistant
Contact
Additional Florida Locations
Orlando, FL (77.8 miles)
121 South Orange Ave
Suite 1543
Orlando, FL 32801
Phone: 888-218-9483
Email: Send a message
Miami, FL (205.6 miles)
1001 Brickell Bay Drive
Suite 2700 M-1
Miami, FL 33131
Phone: 888-276-5244
Email: Send a message
Montana Locations
Billings, MT (1,882.5 miles)
1925 Grand Avenue
Suite 127 PMB 535
Billings, MT 59102
Phone: 888-276-5244
Email: Send a message
Missoula, MT (2,147.3 miles)
3010 Santa Fe Court
First Floor - Number 2002
Missoula, MT 59808
Phone: 888-276-5244
Email: Send a message
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