i dont think they are without a permit. a local store got busted for having one but i dont really remember the outcome of it. they got shut down temporarily but ended up getting the majority of their stock back and reopened
i would go to your local library and check out your countys/citsys/towns local laws. here in wi some counties have the banned and others do not. in milwaukee county they are banned, but in ozaukee county just north of it they arent. so umm yeah check out your local laws and regs