Flashing your lights to warn other drivers about the police doesn't only make you a good person, it makes you a good American. A federal judge in St. Louis ruled that the illuminated warning is a legally protected form of free speech

The case came after an old man was pulled over in Ellisville, Mo. for warning other drivers about a radar trap. He sued the city, and the ACLU quickly stood behind him. "In our view that's speech that's protected by the First Amendment," ACLU attorney Tony Rothert said, "and it's also good for the public because it tells people to slow down, to use caution. That's never a bad thing."

It's also worth noting that New York Times ethicist Chuck Klosterman once wrote that warning possible speeders isn't unethical. We're not going to sit here and argue with a federal judge and Chuck Klosterman. 

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[via Autoblog