Actually, there is such a law. In Florida: "A person who willfully, maliciously, and repeatedly follows [or] harasses ... another person and makes a credible threat to that person commits the offense of aggravated stalking, a felony of the third degree." Fla. Stat. § 784.048.Ummmm... I said this a long time ago and I'm not even a lawyer.
(17 years of informed commentary)