Klingon weapons are already banned in some states.

There was a thread on Slef-Defense Forums a few years ago on some anti-knife laws and one weapon banned in some states was a "trefoil." I've never heard of a weapon by that name so I did a search for the term and the only times I could find it in the context of a weapon were other state laws (these idiots copied each other word-for-word) and Star Trek. What probably happened is some Leftist lawmaker saw an episode of ST and wanted to ban the Klingon weapon and wrote the law and other idiots copied the law that fool wrote.
A ST fan may also have written his congressfool as a joke to see if he could ban something that doesn't exist. Maybe someone will do that with weirding modules or Gom Jibbars.
Another possibility is that it was another display of total ignorance and someone saw an ad for shuriken and one type of 3-pt was labeled a "trefoil," (I think I saw an add like that) though the problem with that is that it would make no sense to single out one type of shuriken and list it by itself and other shuriken group together as "throwing stars." This possibility would make sense if the law was written in the mid-1980s before STNG aired.