You're driving down a two-lane highway, moving at roughly the speed of traffic, perhaps a few miles per hour over the speed limit. Your passenger recommends to you that you slow down because of a well-known speed-trap area ahead. Good advice, right? But what about another passing motorist? Is it legal to flash your headlights at oncoming traffic to let them know of police presence in the area?According to a federal judge in St. Louis, flashing your headlights to warn of upcoming speed traps is a legally protected form of free speech and is therefore protected by the First Amendment, says Fox 2 News. The ruling came after police in Ellisville, MO, pulled over Michael Elli, a retired man with a clean driving record, for flashing his lights to warn motorists that police were using their radar guns ahead. Elli sued the city, and the American Civil Liberties Union joined him in the suit shortly thereafter.We agree with the assessment of ACLU attorney Tony Rothert, who said, "In our view that's speech that's protected by the First Amendment and it's also good for the public because it tells people to slow down, to use caution. That's never a bad thing." What about you? Should flashing headlights to warn oncoming traffic of a speed trap be legal? Watch the video , then make your voice heard in our informal poll below.