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Lieutenant Colonel, U.S. Army (Retired)


Criminal Investigations

Administrative Investigations

Military Medical Privileging/Credentialing

Adverse Administrative Actions

Court-Martial Representation

Mangan Law

The Law Offices of Sean F. Mangan, PLLC

Lieutenant Colonel (Retired) Sean Mangan’s career in law, criminal justice, and the military spans 30+ years.  He has worked every aspect of the system, from investigating cases as a law enforcement officer to presiding over court as a trial judge.  In the years between, he handled cases from every angle as a legal advisor, prosecutor, defense counsel, military magistrate, and appellate attorney.

Law Enforcement Background

This is where it all began.  Sean’s involvement with Law Enforcement goes back decades to his time with the Spokane, Washington Police Department.  That’s where he first learned investigative procedures and the ins-and-outs of evidence handling.  His time in a patrol setting gave him valuable insight into the realities of how crimes are investigated.  Later, he served in the Army’s Military Police Corps, where he expanded and added to his law enforcement knowledge in the military world.  Years later, after becoming an attorney and joining the Army JAG Corps, he trained DA Police Officers on law and procedure.  Today, that experience makes Sean Mangan uniquely effective when reviewing and challenging investigations and helping his clients navigate that process.

Operational Experience

A distinguished military graduate (DMG) and commandant’s listee, Sean Mangan excelled early in his career.  His time in the Military Police Corps, including command experience and time as a battalion staff (S3) primary, gave him valuable perspective and operational experience.  Sean’s operational deployments have seen him serving real-world missions in North Africa, the Middle East, and the Balkans.

Distinguished JAG Career

Selected for the highly competitive Funded Legal Education Program, Sean attended law school while on active duty, supporting JBLM legal operations between semesters and trying cases as an intern prosecutor for the Lane County, OR, District Attorney’s Office while in law school.  In the Army JAG Corps, he served the full range of Military Justice jobs.  He prosecuted military crimes in courts-martial and civilian cases as a Special Assistance U.S. Attorney.  He advised commanders at all levels on a wide range of legal issues.  He then did appellate work, taking cases up before military appellate courts and petitioning the Supreme Court of the United States.  While deployed he worked with Tier-1 Special Operations Forces, prosecuting terrorists in foreign courts.  Later, after obtaining his Master of Laws (LLM) with a certificate in Criminal Law, he trained thousands of JAGs, commanders, and even military judges while serving as a Professor of Criminal Law at TJAGLCS, the military’s only ABA-Accredited Law School.  He then supervised the Army’s busiest Trial Defense Region, where he represented general officers, commanders, and high-profile clients like SGT Bowe Bergdahl.  Finally, Sean was hand-picked by the Judge Advocate General to preside over courts-martial as a Military Trial Judge.  Throughout his career, Sean Mangan helped build and improve the system, contributing to and creating courses, forms, and other resources still in use today, including authoring significant revisions of the Army’s military justice regulation while a Senior Policy Attorney at the Pentagon.

Personal Note from Sean

“Like many, I used to think that military personnel shouldn’t need to hire an attorney.  Having supervised dozens of them, I have the utmost respect for detailed military defense counsel.  But my time in TDS showed to me the crushing caseload and curtailed mandate that severely limits the help these young, hard-working attorneys can provide.  

I came to realize that, when it’s YOUR life and livelihood at risk—either because of an allegation against you or a mistake you made—private representation is a must.  Having someone who is outside the system and completely dedicated to you as a client brings a level or advocacy and assistance that just is not otherwise available.  Yes, hiring a private attorney is a big deal.  But, after 30 years of seeing the system from all sides, I am certain that the difference it makes, both in your case and in your career, is even bigger.  

Today, I dedicate my legal skills and knowledge to those who have chosen to serve.  I believe that every servicemember deserves straight talk about their legal situation, which is why I do free consultations every day.  I choose which cases I take on because each one matters to me.   If I accept and earn your case, I will leverage every bit of my experience, skill, and knowledge to ensure you get the justice you deserve.”

I am ready to fight for you!





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The Law Offices of Sean F. Mangan, PLLC

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