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Sean Mangan


The Law Office of Jocelyn C Stewart, Corp. is proud to have Sean F. Mangan is Of Counsel to our firm.  Joining us after a highly successful Army JAG Corps (JAGC) career, Lieutenant Colonel (Retired) Mangan brings an unmatched range of experience to the Stewart legal team.

A seasoned attorney and criminal law expert, Sean holds a Master of Laws (LLM) degree, a Top Secret (TS/SCI) security clearance, and a “Master Military Justice Practitioner” Army Skill Identifier (ASI).  With time in both civilian and military courts, Sean Mangan has a proven track-record in criminal cases and adverse administrative actions.  His former clients include commanders, general officers, and high-profile servicemembers.  Having done virtually every job in the criminal justice system—investigator, prosecutor, defense counsel, appellate counsel, and trial judge—Sean is able to provide our clients with superior advice and representation in both military and civilian criminal matters.

Law Enforcement Background

Sean has law enforcement experience in both civilian and military agencies. His law enforcement training, background, and experience gives him unique insight into how those investigations are conducted.  Sean also knows what to look for in challenging and dismantling them.  He knows what areas they failed to investigate and how best to expose investigation bias.

Legal Experience at All Phases

His legal experience is even greater:  Sean has prosecuted criminal cases in state courts, federal courts, and military courts.  He has personally represented high-ranking clients in sensitive matters and led the Army’s busiest trial defense region.  On behalf of those already convicted at the UCMJ trial level, Sean authored and argued appeals to their court-martial convictions to military appellate courts and the Supreme Court of the United States.  While deployed, Sean prosecuted international terrorism cases in foreign courts.  Given his legal acumen, wisdom, and overall insight to the military justice process at all stages, Sean was selected to serve as a military trial judge.  While serving as a trial judge, he presided over trials involving rape, aggravated assault, drugs, larceny, military-specific offenses, among others.  His position as trial judge put him in a position to rule on all manner of legal issues. As the landscape of military justice practice shifted with new appellate decisions, Sean was tasked with drafting implementing changes to the script used by all trial court judges.

Teaching & Policy Experience

Sean Mangan taught thousands of attorneys as a Professor of Criminal Law at the Army’s ABA-accredited law school.  He assisted counsel in honing their knowledge of case law and procedure, and coached them in trial skills.  Notably, Sean also taught several iterations of the judge’s course, a requirement for any military judge to serve in each of the services.  Before retiring, he served as a senior criminal law policy attorney at Army headquarters.

As a former Military Police Officer, Judge Advocate, Professor, and Judge, Sean is among the most knowledgeable individuals on military justice and criminal law.  Unlike most retiring judge advocates, Sean’s knowledge of military law is not stale. He is current on cases and practices, and is poised to take on zealous representation.

Post-Service Experience and Specialties

In the 3 years since he retired and joined the Law Offices of Jocelyn C. Stewart, Sean has helped over 100 service members save their careers by fighting for them at all stages of the military justice system.  He has convinced investigators to favorably close cases, persuaded commanders to resolve misconduct through minor or no action, secured retention at separation and show cause boards, and fought cases to acquittal at trial.

In addition to handling military investigations, prosecutions, appeals, and adverse actions, Sean is available to represent service members and their family members facing civilian criminal charges in local, state, or federal courts. Sean is a member of the Washington State Bar, Oregon State Bar, United States Supreme Court Bar, and is admitted to practice before both Army (ACCA) and federal military (CAAF) appellate courts.

More About Sean Mangan


Our Practice Areas

Being a former service member herself and working exclusively on military cases, Ms. Stewart has amassed experience to help in the following areas of the UCMJ:

What Our Clients Say

When faced with the decision of hiring a UCMJ specialist, Ms. Stewart’s former clients explain all that is necessary about her commitment to their case and her expertise in handling the toughest legal battles. Learn more about her unique abilities in the words of her clients, peers, and military judges.