Is it legal to flash your headlights to warn other drivers of a speed trap?
We've all seen other drivers do it and many of us have done it ourselves: Someone drives through a speed trap and then starts flashing their lights to warn other drivers of the speed trap. It is 100% effective at ticking off the police, but is it legal? Missouri passed a law making it illegal. A very good argument can be made that we should be assisting the police and warning other drivers of a speed trap is only making their jobs more difficult and making the roads less safe. That's probably true in many cases. In other cases, speed traps seem to be as much about revenue as safety. When I was in law school in Ohio I recall a town that had claims to literally a 1/4 mile of the interstate and there was almost always a speed trap. Everyone knew that it was less about the town's concern for safety on its 1/4 mile stretch of highway than about revenue.
The ACLU has challenged the Missouri law on free speech grounds and was granted a preliminary injunction. Judges grant preliminary injunctions only when it appears likely that the party will ultimately prevail on the merits so it is a pretty good signal that the judge considers the law to be unconstitutional. It will be interesting to see what happens as the case climbs through the court system.
Have a safe weekend everyone.