Mark J. O'Brien

Attorney Mark J. O’Brien started his own law firm on January 1, 2003. After nearly thirty years, Mr. O’Brien has expanded his firm beyond himself. Now named O’Brien Hatfield, Mr. O’Brien’s law firm has seven lawyers, one paralegal, four legal assistants, two private investigators (a retired IRS CID special agent and a retired DEA special agent), one sentencing mitigation specialist (a former United States Probation Officer), and numerous third-party experts who assist on a case-by-case basis. Mark is a member of the bars of Florida (1998), Massachusetts (1998), and Montana (2023). Mark is permitted to practice federal criminal defense law in every federal criminal court in America. Mark grew up and attended college in New York, attended law school near Philadelphia, and started his career as a prosecutor in Miami. As a result, there is almost nothing Mark has not seen, done, or dealt with in or out of a criminal courtroom over the course of his career. New York raised, Philly tough, and Miami tested, Mark brings nearly thirty years of criminal court experience to those accused of crimes in federal criminal courts throughout the entire nation. Mark has the resources, both in his team and in his experience and his training, to tackle your federal criminal case and accomplish the only objective that matters: Win. Thus, if you are being investigated and/or prosecuted by federal agents and/or federal prosecutors and are need of a federal criminal defense attorney – and a federal criminal defense team – anywhere in the United States of America, all Mark needs is a Wi-Fi Password and a plane to defend you.