Mark J. O'Brien

Mark J. O'Brien is the founding partner of O'Brien Hatfield, PA, located in Tampa, Florida. Representing clients throughout the state, he focuses his practice exclusively on criminal defense matters at the state and federal levels, including white collar crimes, drug offenses, securities fraud, sex offenses, mortgage fraud and criminal appeals.

Mr. O'Brien pursued his undergraduate education at Siena College and received a Bachelor of Arts in English literature in 1995. After graduating from Delaware Law School and being awarded his Juris Doctor in 1998, Mr. O'Brien was one of only 44 applicants out of 4,000 who were hired to work as prosecutors for the Miami-Dade Office of the State Attorney, 11th Judicial Circuit. His three years in the office's felony division helped him to hone his skills as a trial lawyer as he tried numerous cases through to verdict.

Mr. O'Brien is admitted to practice law before all of the state courts of both Florida and Massachusetts. He is also admitted to practice before the U.S. District Courts for the Southern, Middle and Northern Districts of Florida, the U.S. District Court for the Western District of Texas, the U.S. District Court for the District of Massachusetts, the U.S. Courts of Appeal for the 1st and 11th Circuits, and the Supreme Court of the United States.

Highly regarded by his fellow professionals, Mr. O'Brien has received a "Superb" peer review rating through Avvo. He is an active participant in numerous legal organizations, including the National Association of Criminal Defense Lawyers, the Florida Justice Association, the Florida Association of Criminal Defense Lawyers and the Federal Bar Association.