“since two separate “sovereigns” would be involved, how is that different from being tried in state and federal court for the same actions?”
As follows: Generally, if a crime is committed downtown, the military authorities will let the locals handle it. Although AD members are subject to the UCMJ 24/7, military authorities will cede jurisdiction to the locals if the major impact was in the local community (off-base DWI, assault on a civilian, etc.) AND it isn’t a peculiarly military offense (AWOL, Stupid on Station, Art 133-134, disobeying lawful order, etc.). There’s case law that makes a subsequent court martial after civilian conviction double-jeopardy but I don’t have it at my fingertips. Even multiple charges and specifications within a CM can be duplicative (”duplicious”, we call it - dunno why...) for sentencing purposes, meaning dual punishment for the same conduct.
Colonel, USAFR
I think that must be the key. I was thinking of dual prosecutions. The second after the person was acquitted of the charges in the first prosecution for the same conduct, even though the charges might be different though based on the same conduct.