The Navy-Marine Corps Court of Criminal Appeals saw four judges agree against three others that a retired military service member can be court-martialed. Retired Chief Petty Officer Stephen Begani appealed his conviction after pleading guilty to attempted sexual assault and attempted sexual abuse of a child, because he had been transferred to inactive service at the time. The NMCAA agreed and overturned his 18-month sentence until an appeals court withdrew the opinion four months later. Judge Marine Lt. Col. John Stephens has stated that part of the decision rested on Begani’s membership in the Fleet Reserve.
Source: https://www.military.com/daily-news/2020/01/29/military-retirees-can-be-court-martialed