I know this is an old post, but maybe there are others with the same question who are contemplating JAG...the AF JAG answer is completely wrong. I was an Army officer for a number of years before coming to law school and no one goes to those schools unless there is a need, especially if you are not a combat arms branched officer (i.e., infantry, armor, field artillery, etc).
Airborne: If you are in an airborne unit (basically, just the 82nd Airborne Division), you WILL go to airborne school (b/c the 101st Airborne Division sends its soldiers to Air Assault school (helicopter rappelling))....it's essentially a requirement. If you are not in that division (like 95% of the rest of the army), you WILL NOT go to airborne school. Pretty much no exceptions, especially if you are a JAG officer
Ranger School: Unless you are a new Infantry 2nd Lieutenant or enlisted soldier specifically assigned to a Ranger unit, you WILL NOT go to Ranger school. The only exception would be if you were assigned as a JAG officer to a Ranger unit (but they don't have JAG officers in their units...JAG officers are assigned to the division, etc, and perhaps a JAG or two will be attached to the HQ of a Ranger BN for particular needs, but will not be in a Ranger Battalion). And, by the way, if they do need to do that, they will probably just pick a JAG lawyer who already has a Ranger tab (as there are a few) by virtue of being an infantry officer first and then going to law school later through the Army's funded legal education program (FLEP).
The bottom line is that those two schools cost the Army a lot of money and they send people on a needs of the Army basis. If you are a JAG officer, you have no need for advanced combat training in the eyes of the Army. You will be assigned to JAG sections at higher headquarters levels and if you deploy to a combat zone you will be with large headquarters units and not sent out to fight or patrol. As such, there is no justification for the Army to spend that money on you and they won't do it. Oh, and the airborne badge is not that prestigious like AF JAG thinks...it certainly doesn't equate to "instant advancement" or even guaranteed deployment...you deploy based on your unit. When you are in the Army, you move from post to post every couple of years, so if you go to 82nd Airborne, you'll get the badge at that time...(so if you really want it, try to get Fort Bragg as your first post...although make sure you inform yourself on the sometimes tiring "gung ho" attitude of the post...it's not a personality fit for everyone).