Co-Founder & National Security Law Attorney
Brett J. O’Brien is the co-founder and owner of National Security Law Firm, LLC, bringing one of the most comprehensive and deeply specialized backgrounds in national security law available in private practice today. A VA accredited attorney, Brett has dedicated his career to mastering the complex intersection of federal law, intelligence operations, security clearances, and administrative proceedings — giving his clients an unmatched advantage when their livelihoods, businesses, and careers are on the line.
Unparalleled National Security Expertise
Brett’s expertise is not theoretical — it was forged through years of hands-on service as an Intelligence Law Attorney with the United States Army Intelligence and Security Command (INSCOM), where he served as the primary legal advisor on all active counterintelligence (CI) investigations across the United States Army. He routinely advised commanders on the full range of CI activities, cyber operations, intelligence oversight, and operational law, interfacing directly with the FBI, NSA, Defense Intelligence Agency (DIA), Department of Treasury, and other members of the Intelligence Community.
His deep knowledge of the laws, regulations, and policies governing national security matters — including Executive Orders, Department of Defense Directives, Army Regulations, the Freedom of Information Act (FOIA), the Privacy Act, and the Electronic Communications Protection Act (ECPA) — gives him an insider’s understanding of exactly how the government builds its cases and makes its decisions.
Security Clearance & Credentialing Authority
Brett has an exceptional command of the security clearance process, having spent years on the government side advising on clearance adjudications, classified information handling, and security violations before transitioning to private practice to advocate for individuals and companies.
Military Service
Brett has served as a Judge Advocate (JAG) officer in the United States Army Reserve, rising to the rank of Major. His military legal career has spanned intelligence law, cyber law, trial practice, administrative law, ethics, and civilian personnel law. He has successfully prosecuted courts-martial, litigated before the U.S. Merit Systems Protection Board (MSPB), advised on Equal Employment Opportunity (EEOC) matters, and supported the Army’s Litigation Division on complex federal cases.
Education & Teaching
Brett earned his Juris Doctorate from Case Western Reserve University School of Law, where he co-founded the National Security Law Concentration and the Military Law Society, and was awarded the Case Western Global Award in International Law. He holds a Bachelor’s degree in Economics and History from Denison University.
He has served as an Adjunct Professor at the University of Texas San Antonio, teaching Cyber Ethics to undergraduate students, and as a guest lecturer at INSCOM’s Intelligence Law Course, where he trained national security attorneys on social media exploitation and intelligence oversight.
Bar Admissions & Credentials
Brett is admitted to the bars of New York, Ohio, New Jersey, and Washington, D.C., and has been a member in good standing since 2011. He has completed an extensive range of specialized military legal education, including the Naval Classified Litigation Course, DIA Counterintelligence and HUMINT Legal Workshop, Federal Litigation Course, and multiple iterations of the INSCOM Intelligence Law Course.