Headlight flashing is the act of a driver flashing their headlights at an oncoming driver by briefly turning the headlights on or off, or from high beam to low beam, or low beam to high beam. There is no set or clear message transmitted by headlight flashing, but it often means the driver who flashes their headlights believes the oncoming driver’s headlights are inappropriately on high beams or are not turned on or illuminated when they should be.

Headlight flashing may also be intended to convey other messages, such as warning another driver of the flashing driver’s presence; telling another driver to proceed in front of the flashing driver (yielding the right of way); or warning an oncoming driver of danger ahead—which may include a deer or other animal in the road, an automobile wreck, or a police officer hidden from view who is checking the speed of passing drivers and issuing speeding tickets (a speed trap).

Police officers have sometimes issued traffic tickets to drivers for headlight flashing, and in some instances a traffic stop for headlight flashing has led to more serious charges and an arrest for DUI/DWI, for example. Tickets for headlight flashing are often issued based on an alleged violation of a municipal ordinance or a state statute that prohibits:

• high beam headlights within a certain distance (500 feet, for example) of an oncoming driver;

• aggressive driving;

• having flashing lights on a vehicle; or

• obstructing a police investigation.

Drivers who have received tickets for headlight flashing have sometimes challenged the ticket—or the traffic stop that led to an arrest and additional charges—on the ground that headlight flashing is a communication protected by the First Amendment to the United States Constitution.

Laws and ordinances vary from state to state and among cities and towns (municipalities), and state and federal courts have arrived at different conclusions when applying the First Amendment and other laws and ordinances to traffic tickets or stops based on headlight flashing.

In Ohio, headlight flashing is not explicitly prohibited by state law, but it can be subject to interpretation under various traffic regulations. Ohio law requires that drivers dim their high beams when approaching an oncoming vehicle within 500 feet or when following a vehicle within 200 feet (Ohio Revised Code Section 4513.15). While there is no specific statute that addresses headlight flashing, actions such as flashing headlights could potentially be considered under statutes related to the use of high beams or distraction to other drivers. Additionally, flashing headlights could be interpreted as a form of communication, which some drivers have argued is protected under the First Amendment. However, this defense's success can vary depending on the circumstances and the court's interpretation. It is important to note that while headlight flashing to warn of a speed trap is a common practice, it could be seen as obstructing official business, although this is not commonly enforced. Drivers who receive tickets for headlight flashing may challenge the citation in court, and outcomes can differ based on the specifics of the case and the jurisdiction.