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 Washington State, the practice of headlight flashing is not explicitly addressed in state statutes. However, drivers may be cited under various traffic laws if the action is deemed inappropriate or unsafe. For instance, Washington law (RCW 46.37.230) requires that high beams must not be used within 500 feet of an oncoming vehicle, which could be relevant if a driver is flashing their high beams at oncoming traffic. Additionally, using flashing lights is generally restricted to emergency vehicles (RCW 46.37.185), and non-emergency use could potentially be cited under this statute. While headlight flashing could be interpreted as a form of communication, and thus potentially protected by the First Amendment, such defenses would depend on the specific circumstances and have varied outcomes in courts. Drivers should be aware that while headlight flashing is a common practice, it can lead to traffic stops and citations if it is considered to violate traffic laws or is seen as aggressive driving.