Some groups speaking obscure languages have tried to claim proprietary
rights over their languages, generally so they can forbid outsiders from
speaking it or try to control what's said in it.
None of these claims have been tested in court, all have been met with
hilarity from everyone I know of who's heard of them, and the general
opinion of such attempts is that they're doomed to failure. (It'd have no
chance of success with major languages, of course. The closest they get is
the Academie Francaise...)