The law is unconstitutional... if a trained police officer can’t know whether its illegal to possess a given type of weapon, enforcement is likely to be arbitrary and capricious. It cannot be enforced fairly since the average citizen has no way to know in advance if he is in compliance with the law. The law’s constitutional defect cannot be cured. It must be struck down.
The "capricious" part goes all the way to the top of the state's law-enforcement community, too. IIRC, a change in the attorney general's office resulted in a re-interpretation of the exemption of SKS rifles from the ban, and a mandatory "turn them in or dispose of them otherwise" order. I wonder what the compliance rate was, back in 1999 - 2000.