You are dead on NavOffRec - you have to have prior JAG experience to get into the Navy Reserve JAG Corp - Air Force is competitive too, but not as much. I came very close to landing a slot with Mass Air National Guard as a JAG last winter - even with what lacks in my law pedigree - I shine in other ways.and don't forget like RUFIO said, you have to have at least 1 year military experience for JAG, so he isn't even eligible.
I did put a girl in who's sister is or was AF attorney, she was very smart, near perfect GPA's for all her degrees, not sure if AF is still as competitive as USN JAG but if it is you pretty much need to walk on water to get in.
I had a break in service though (re-enlisted Feb 18 - Selected DCO Sept 18 Board) and the Air Guard had to give consideration to current air guard or reservists applying for the gig. I walked out of that board convinced they wanted me. My enlisted escort that got me on and off base told me that I knocked the interview out of the park and that I was the best candidate they had seen. Had a nice follow up with CO by e-mail too.
Didn't get the gig. I ran into the recruiter that got the competition in later - turns out they loved me - but they took a Mass Air Guard E-4 that just finished law school over me because they felt the need to look out for one of their own trumped other stuff - and you know what - I begrudgingly agree in most circumstances...