What this will come down to
Look guys there are a couple different ways this can go down.
1.) What alot of you fellas are critical of is the age (young enough to die for your country...etc.) That is a loser. What you would be doing there is attacking the law as denying equal protection under the laws due to the age of the plaintiff (being 18-20). That's going to probably lose. Hard. All the gov. has to prove is a rational basis for the law.....and that basis can be very, very, very, loosely tied to the law.
Which is why the NRA has waited until now....when the Supreme Court has ruled the right to bear arms a fundamental right THAT APPLIES TO THE STATES (through the 14th amendment). Leading us to:
2.) Fundamental right (and this is how plaintiff is doing it) Uncle Sam is going to have to prove 2 things:
A.) Narrowly tailored legislation tied directly to
B.) a compelling state interest.
Basically, Uncle Sam has to prove an exceptionally good reason for the law, and must show their is no real better way of accomplishing that goal.