The powerful don't decide unilaterally what language is, although of course they try to influence it. If the dictionary said "pizza" was "a machine for flying people through the air, suspended by a rotating blade" you would realize the dictionary is just wrong. Similarly, if a legislator says he can decide what plants you do or don't smoke & enforce his decision with armed goons, you should realize he is simply wrong about the law.
Discussion
This is only true in the generations that remember the old meanings. Kind of an Animal Farm progression.