A US district court has ruled that a defendant will be allowed to argue to a jury (within limits) that the Second Amendment bars his prosecution for possession of unregistered machineguns.
Normally you wouldn't be allowed to argue interpretation of a law, let alone the argument of unconstitutionality, to a jury. That's for the judge to decide. But the court says it wants a wide-open record. And, frankly, it'd make what would be a boring trial (limited to did he possess the gun, was it tax-paid, and to a minor degree what was his state of mind and knowledge) into something halfway interesting, and I think trials should be interesting.