Hom Tanks in the comments wonders if the covered offenses in the NDAA will constitute most offenses actually tried. Per a preliminary look at Air Force data for FY21, the answer is "yes."
107 of 159 GCMs included a covered offense or 67% of all GCMs in FY21.
8 of 122 SpCMs included a covered offense or 6% of all SpCMs in FY 21.
Thus, while the number of offenses "covered" seems small in relation to the whole code, the reality will be that the new system will be the primary system meting out military justice. Of course, this could change should patterns of criminal conduct (or prosecutorial priorities) change.
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Joint R. App. Pro.
Global MJ Reform
LOC Mil. Law