The National Institute of Military Justice is the country's only non-governmental organization dedicated solely to the study and improvement of the military's justice system. NIMJ members include prominent law professors and practitioners, as well as leaders of think tanks and non-profits. Membership is by invitation only.

NIMJ was formed in 1991 by Eugene R. Fidell, Captain Kevin J. Barry, USCG (Ret), Rear Admiral John. S. Jenkins, JAGC, USN (Ret), and Professor Stephen A. Saltzburg.
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In the ensuring years, NIMJ has been actively involved in military justice, filing amicus curiae briefs, publishing books on the rules of practice, suggesting changes to the UCMJ and the Manual for Courts-Martial, sending observers to the military commissions at Guantanamo Bay, providing expert commentary to news media, and sponsoring conferences and events.

NIMJ is not a government agency. Its views should not be imputed to any agency or other institution. NIMJ does not provide legal services or recommend attorneys.