O'Brien Hatfield, P.A.



Serving clients in communities throughout Florida.


If you've been charged with a crime, you may be facing devastating consequences. The knowledge and resources of an experienced criminal defense attorney can be the difference between a conviction and a dropped charge.

Extensive Experience

Our firm has provided Florida clients with strong representation since 2001.

Recognized By National News Outlets

Our cases have been featured in The Miami Herald, Bay News 9, ABC 7, The Boston Globe, USA Today, and numerous others.

Numerous Prestigious Associations

Including American Association for Justice, National Association of Criminal Defense Lawyers, and Florida Association of Criminal Defense Lawyers.

Hiring the right defense attorney is the first step in protecting your rights.

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Contact Information

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Mark J. O'Brien's cases have been featured in:
  • Client, Jim F.

    "This is one of the finest law firms that I could ever be affiliated with."

  • Client, Colandra

    "Thank you from the bottom of my heart for how you have handled everything with this case."

Aggressive Advocacy For Defendants

Mark J. O’Brien has over 20 years of experience in criminal law. As a former prosecutor who has handled hundreds of criminal defense cases, Mark has unique experience dealing with criminal cases on both sides of the law.

Since becoming a defense attorney, Mark J. O’Brien has won dozens of cases for his clients. Our firm can handle the details of any criminal charge including:

Violent Crimes
These crimes include murder, manslaughter, assault and battery. We help our clients prove their innocence and avoid the harsh penalties of a conviction.

Sex Crimes
Our firm is prepared to defend you from serious accusations. We’re here to defend your rights and protect your name.

Theft and Fraud
Serious crimes require a serious defense. Our firm is capable of handling any charge, including federal, state and appellate cases.

We are prepared to defend charges for both theft and fraud cases. No matter what the charge, we have the answer.

At O’Brien Hatfield, we understand the importance of reputation. So there is no such thing as a small case to us.

When it comes to criminal defense, time is of the essence. O’Brien Hatfield is ready to put their decades of experience to work on your case.

Defend your rights. Protect your future. 813-773-0767