- Sometimes, it can "pay" not to immediately pay your traffic ticket...
Flashing your headlights to warn an oncoming driver about a speed trap is, in most places, legal. Courts have said so repeatedly. The move feels illicit because it feels like interfering with police work, and because a cruiser on the shoulder radiates the kind of authority that makes drivers assume any signal to the other side of the road must be against the rules. Judges across the country have ruled the opposite, often on First Amendment grounds, and the handful of tickets that still get written tend to collapse the moment anyone pushes back.
The confusion carries a cost. Drivers who think a quick flash will cost them their license don’t send one, and drivers who get ticketed for it often pay the fine rather than fight. Both groups are reacting to a rule that mostly doesn’t exist, and both are missing where the real legal exposure sits, which is after a crash, not after a flash, and usually in a conversation with a car accident attorney. Here’s what people get wrong, one assumption at a time.
It’s a Traffic Violation Everywhere
The clearest counterexample is the one that put the whole question on the map. In 2014, a federal judge in Missouri ruled for Michael Elli, a driver ticketed in a St. Louis suburb for flashing his lights at oncoming traffic to warn about a radar setup, as NBC News reported at the time.
The city had charged him under an ordinance aimed at flashing signals on school buses and emergency vehicles. The court’s opinion found that the flash communicated a message, that the message was lawful, and that punishing drivers for sending it chilled protected speech.
State courts in several other jurisdictions have reached similar conclusions over the years.
Some lean on the First Amendment. Others point out that the underlying traffic statutes were written to govern equipment and emergency signaling, not driver-to-driver communication. Either way, a quick flash to warn a stranger isn’t the conduct these laws were built to punish.
The Officer Can Stop You Just for Flashing
A traffic stop requires reasonable suspicion that something unlawful is happening. If the conduct the officer observes, a brief high-beam flash at an oncoming car, isn’t a violation, the stop itself is on shaky ground. That was a central part of the Missouri ruling, and it’s the reason tickets written for the flash alone tend to get dismissed or quietly dropped before trial.
A stop can still happen. Officers pull drivers over, cite them, and let the courts sort it out later. The practical cost of being right is an evening on the shoulder and a court date you didn’t want. But the ticket itself usually doesn’t survive scrutiny when a driver contests it with a lawyer who knows the case law.
The Flash Itself Can Cost You a License
The scarier version of the fear is that a flash will put points on your record, hike your insurance, and eventually cost you the ability to drive. Even in jurisdictions where an officer writes the ticket, the underlying charge is usually a low-level equipment or signaling violation, not a moving violation tied to a crash risk. Those don’t carry the same consequences, and when the ticket is challenged on grounds other courts have already accepted, it often doesn’t survive.
Real license trouble starts after a collision, not after a flash. If a driver was warned, slowed down, and still rear-ended the car ahead, the fight becomes about speed, following distance, and attention. That’s the ordinary stuff of a crash claim, not the semiotics of your high beams on the roadside.
What to Do If You Get Ticketed Anyway
Don’t pay it reflexively. Paying the fine is often an admission that closes the case and puts the violation on your record. If you intend to contest it, say so at the roadside and again on the citation.
Write down what happened. Note the time, the location, the direction of the oncoming car, and what the officer said the violation was. Memory fades fast, and the specific wording of the stop matters later.
Pull the ordinance. Look up the exact statute or municipal code cited on the ticket. Many of them, read plainly, don’t cover a brief courtesy flash. They’re about equipment, emergency vehicles, or sustained use of high beams against oncoming traffic.
Get a lawyer who’s seen it before. A traffic defense attorney in your area will know whether local courts have followed the national trend. In most places, a short motion citing the relevant case law is enough to end the matter.
The Signal Isn’t Going Away
Legislatures occasionally take a run at codifying what the courts have already said. A New Jersey bill to make the practice explicitly legal is one example, and similar proposals have surfaced elsewhere.
Whether or not those bills pass, the underlying driver habit is older than radar and will outlast whatever enforcement fashion is running this year. People warn strangers because strangers warned them. The law, in most places, has made peace with that.