Under the U.S. Constitution, the government can't censor your freedom of speech without proper justification. Which begs the question: Is flashing your headlights protected speech?
A judge in Oregon last week ruled that drivers have a First Amendment right to flash their headlights to warn oncoming vehicles about speed traps. The citation given to truck-logger Chris Hill of Klamath Falls—a $260 ticket—"was clearly given to punish the Defendant for that expression," wrote Judge Joseph Carter. "The government certainly can and should enforce the traffic laws for the safety of all drivers on the road. However, the government cannot enforce the traffic laws, or any other laws, to punish drivers for their expressive conduct."
Earlier this year, a federal judge in St. Louis made a similar ruling in a lawsuit brought by the American Civil Liberties Union of Missouri. According to the ACLU, this was the first federal court ruling on the issue.