Presumably OP is thinking of libel laws, because accusing someone of talking a bribe is tantamount to accusing them of breaking one of any amount of anti-corruption laws. I'm (extremely) doubtful of the claim since the plaintiff would have to prove in a court of law that bribery can only possibly refer to a specific action (breaking one of the above laws) that he did not commit.

Though the threat of a lawsuit may be enough.