Co-Founder | National Security Law Attorney
Former Intelligence Law Attorney for U.S. Army Intelligence and Security Command (INSCOM) and Advisor on Counterintelligence, Personnel Security, and National Security Matters
Brett J. O’Brien has spent his career working at the intersection of intelligence, counterintelligence, personnel security, government investigations, and national security law. Before co-founding National Security Law Firm, Brett served as an Intelligence Law Attorney for the United States Army Intelligence and Security Command (INSCOM), where he advised military leaders, intelligence professionals, and government officials on some of the Army’s most sensitive security, counterintelligence, and national security matters.
As the primary legal advisor for active counterintelligence investigations throughout the Army, Brett worked closely with the Federal Bureau of Investigation (FBI), National Security Agency (NSA), Defense Intelligence Agency (DIA), Department of the Treasury, and other members of the Intelligence Community. He advised on personnel security concerns, intelligence oversight, classified information issues, cyber matters, investigations, and the legal frameworks governing national security operations.
Through this work, Brett developed firsthand insight into how government agencies identify and assess risk, evaluate trustworthiness, investigate security concerns, determine credibility, and make decisions affecting security clearances, credentials, government employment, and access to sensitive information. His experience provides clients with a rare understanding of not only the laws governing these matters, but also how government decision-makers evaluate the people and facts in front of them.
In addition to his intelligence law experience, Brett served as a Judge Advocate in the United States Army Reserve, rising to the rank of Major. His military legal service included military justice, administrative law, ethics, federal employment matters, Equal Employment Opportunity (EEO) issues, Merit Systems Protection Board (MSPB) litigation, and federal litigation support. He also served as an Adjunct Professor teaching Cyber Ethics and instructed national security attorneys on intelligence law and intelligence oversight matters.
As co-founder of National Security Law Firm, Brett has played a central role in shaping the firm’s substantive expertise and national security focus. Drawing on his experience inside the intelligence and national security communities, he helped build a firm centered on a simple idea: clients facing complex government problems deserve attorneys who understand how government systems actually operate. He has been instrumental in developing many of the firm’s core practice areas and assembling a team that includes former intelligence officials, military leaders, prosecutors, judges, investigators, federal employment attorneys, and security clearance professionals.
Under Brett’s leadership, National Security Law Firm has grown into a multidisciplinary federal practice representing clients in security clearance matters, military law, federal employment disputes, government investigations, credentialing matters, veterans issues, immigration matters, and other cases involving government trust and risk determinations. His philosophy remains unchanged: understanding how government agencies evaluate risk, trustworthiness, mitigation, and accountability is often just as important as understanding the law itself.
Today, Brett focuses his practice on security clearance matters, federal employment issues, military law, administrative investigations, credentialing matters, and other cases involving government trust and risk determinations.
Jurisdictions Admitted: New York, Ohio, New Jersey, and the District of Columbia. Represents clients nationwide in federal administrative, military, security clearance, intelligence, and national security matters.
Education: J.D., Case Western Reserve University School of Law; B.A., Economics and History, Denison University.