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Mark J. O'Brien

Mark J. O'Brien

Your Goal: Freedom. My Goal: As Fast As Possible.
  • Criminal Law, White Collar Crime
  • Florida, Massachusetts, Montana
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Biography

O'Brien Hatfield, PA is a criminal defense law firm that focuses on nationwide federal criminal defense and statewide criminal defense and criminal appeals.

Attorney Mark J. O'Brien is the firm's founder and managing partner. He handles federal criminal cases in federal criminal courts statewide and in federal criminal courts throughout the United States. Formerly a Miami prosecutor, Mark is now widely lauded by federal judges and federal prosecutors as one of the best federal defense attorneys in the country. Mark is so in demand that his office is often an airplane with a WiFi connection. Despite reaching such great heights, Mark still treats each case with the same enthusiasm and energy as he did his first (even though he has practiced law for over twenty-five years).

Mark J. O’Brien, Esquire is a nationally recognized Federal Criminal Defense Attorney with over 25 years’ experience in criminal courts all throughout the country. After beginning his professional career as a Miami, Florida prosecutor in the late 1990’s, Mr. O’Brien organized his own law firm in 2002 based upon the professional lessons he learned to that point in his life with the goal defending those accused of federal crimes with a mix of old school values and new school ideas.

During first decade in private practice from 2002 to 2012, Mr. O’Brien defended individuals and corporations charged with federal crimes throughout federal criminal courts in Florida. From 2012 to the present, Mr. O’Brien has accepted the defense of clients in federal criminal courts throughout the entire country, in addition to his previously established practice in all federal courts in Florida. Case after case, success after success, in federal court after federal court, all throughout the country, has resulted in a growing legacy. To put it simply, Mr. O’Brien wins and, as a result, he is a lawyer in demand.

Practice Areas
Criminal Law
Criminal Appeals, Drug Crimes, Expungement, Fraud, Gun Crimes, Internet Crimes, Sex Crimes, Theft, Violent Crimes
White Collar Crime
Fees
  • Free Consultation
  • Credit Cards Accepted
Jurisdictions Admitted to Practice
Florida
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Massachusetts
Massachusetts Board of Bar Overseers
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Montana
State Bar of Montana
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1st Circuit
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2nd Circuit
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6th Circuit
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11th Circuit
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U.S. Supreme Court
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Languages
  • English
  • Mandarin
  • Spanish
Professional Experience
Partner
O'Brien Hatfield, PA
- Current
Prosecutor
Miami Dade State Attorney's Office Felony Division
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Education
Widener University Delaware School of Law
J.D. (1998)
Widener University Delaware School of Law Logo
Siena College
B.A. (1995)
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Awards
Top 100 Trial Lawyers
National Trial Lawyers
Top 40 Under 40
The National Trial Lawyers
Super Lawyer
Super Lawyers
2016-2024
Professional Associations
Florida State Bar  # 160210
Member
- Current
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Publications
Articles & Publications
Strategies For Defending Identity Theft Cases
Aspatore
Speaking Engagements
Criminal Trial Advocacy, Intensive Trial Advocacy Program
Websites & Blogs
Website
Contact & Map
South Florida Office
1001 Brickell Bay Drive
Suite 2700 M-1
Miami, FL 33131
US
Telephone: (813) 263-4758
Monday: Open 24 hours
Tuesday: Open 24 hours
Wednesday: Open 24 hours
Thursday: Open 24 hours
Friday: Open 24 hours
Saturday: Open 24 hours (Today)
Sunday: Open 24 hours
Notice: Please call or text 813-263-4758for immediate access to attorney Mark J. O'Brien.
Orlando Office
121 South Orange Avenue
Suite 1500
Orlando, FL 32801
US
Telephone: (813) 263-4758
Monday: Open 24 hours
Tuesday: Open 24 hours
Wednesday: Open 24 hours
Thursday: Open 24 hours
Friday: Open 24 hours
Saturday: Open 24 hours (Today)
Sunday: Open 24 hours
Notice: Please call or text 813-263-4758 for immediate access to attorney Mark J. O'Brien.
Tampa Office
511 West Bay Street
Suite 330
Tampa, FL 33606
US
Telephone: (813) 263-4758
Monday: Open 24 hours
Tuesday: Open 24 hours
Wednesday: Open 24 hours
Thursday: Open 24 hours
Friday: Open 24 hours
Saturday: Open 24 hours (Today)
Sunday: Open 24 hours
Notice: Please call or text 813-263-4758 for immediate access to attorney Mark J. O'Brien.