Flashing your headlights is a well-established means of communicating any number of things to other drivers on the road. It could be a reminder for the other driver to turn on their lights (or turn off their brights). Maybe it’s a call to your traveling partners in another car to pull off at the next exit. It’s also a way for some people to alert other drivers about a police speed trap up ahead. Some towns have outlawed that practice, but a federal judge says that’s going too far.

Earlier this week, a U.S. District Court judge in Missouri issued an order that stops, for now, the town of Ellisville, MO, from ticketing drivers who flash their headlights to tip off others to the presence of a speed trap.

The ruling, believed to be the first federal court ruling related to this matter, comes in a lawsuit filed by the ACLU on behalf of a driver who received a citation from Ellisville police in 2012 for flashing his headlights to warn other cars on the road of a speed trap he’d just passed.

The driver says that when he went to court and attempted to enter a not guilty plea on the charge, which generally includes a $1,000 fine, the judge allegedly “became agitated and asked Plaintiff if he had ever heard of ‘obstruction of justice.’”

Charges were eventually dropped against this particular driver, and while Ellisville police have reportedly been told by the Police Chief to no longer cite headlight-flashing drivers, the ACLU sued the town on behalf of the driver because the ordinance still remains on the books and they felt that such a law violates a driver’s First Amendment right to free expression.

The preliminary injunction issued by the court on Monday stated that the plaintiff would likely prevail in his case against the town if it went to trial. According to the judge, the officer who cited the plaintiff for the alleged offense “did not have reasonable suspicion to believe that Plaintiff had violated any law” and stated that it is not illegal to warn drivers “because a speed trap is ahead.”

There are numerous places around the country that have similar laws against tipping off drivers to the presence of a speed trap, and the ACLU is hoping that Monday’s ruling sends a message to lawmakers and law enforcement everywhere.

“It is legal in Missouri to communicate in this manner,” said ACLU Legal Director Tony Rothert after the ruling, “and detaining, ticketing or arresting someone for the content of their speech is illegal.”

Rothert contends that, First Amendment issues aside, warning people of speed traps ahead results in drivers behaving responsibly, saying that in the plaintiff’s experience, “people really do slow down when you flash your lights at them, and that’s safer for everyone.”

Is flashing headlights to warn of a speed trap protected by the First Amendment? [St. Louis Post-Dispatch via LawBlog]

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