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 New Hampshire, there is no specific statute that addresses headlight flashing for the purposes of communication between drivers. However, drivers must comply with RSA 265:15 which mandates the use of headlights from half an hour after sunset to half an hour before sunrise, during any time when it is raining, snowing, sleeting, or hailing, and any other time when visibility is impaired by weather, smoke, fog or other conditions or there is insufficient light to render clearly discernible persons or vehicles on the highway at a distance of 1000 feet ahead. Additionally, RSA 265:4 requires that drivers dim their high beams when approaching another vehicle within 150 feet. While headlight flashing could potentially be cited under aggressive driving laws or for obstructing a police investigation, such instances would be context-specific. Regarding the First Amendment, there is no clear precedent in New Hampshire that headlight flashing is protected speech, and such defenses would likely be evaluated on a case-by-case basis. Drivers should exercise caution and use headlight flashing sparingly to avoid misinterpretation or unintended legal consequences.