Articles Tagged with Optical Horn Flash to Pass

Flashing headlights in North Carolina can mean several things, and to some extent depends on which direction the other vehicle is traveling.

A driver behind you who quickly flashes once or twice wants to pass in the left lane. A driver coming toward you who flashes twice may be telling you your high beams “brights” are on, warning about a deer or a wreck ahead, or signaling that a patrol car is sitting past the next rise looking for speeders. The same gesture, made with the same bright-lights lever, can mean different things and fall under different statutes depending on the setting.

North Carolina does not have a traffic law that says a headlight flash means anything in particular. It has a lamp statute that limits glare toward oncoming traffic, an overtaking statute that gives legal weight to a horn and not a light, and a body of law governing following distance, lane use, and driving conduct that applies no matter what anyone flashes at anyone.

As a practical matter, flashing bright lights almost never gets a driver in trouble by itself. What follows the flash can.

Is Flashing Headlights in North Carolina Illegal?

North Carolina law does not prohibit flashing headlights as a form of communication. The closest provision is N.C.G.S. § 20-131, which governs headlamps and glare.

Under § 20-131(a), a driver operating on the highways, when meeting another vehicle, must control the lights by shifting, depressing, deflecting, tilting, or dimming the headlight beams so as not to project a glaring or dazzling light to persons within 500 feet in front of the headlamp.

Read the words carefully, because the scope is narrower than most drivers assume.

The duty attaches when meeting another vehicle. That describes oncoming traffic. A deliberate high-beam flash at a car approaching within 500 feet is the scenario the statute intends to prevent, and a driver who keeps the high beams on an oncoming vehicle can face real legal trouble.

A brief flash into the mirror of a vehicle traveling the same direction ahead of you is a different matter. You are not meeting that vehicle. You are following it. The statute’s 500-foot glare restriction, by its terms, addresses light projected in front of the headlamp toward persons the driver is meeting.

That asymmetry explains something drivers find confusing. The flash that feels most aggressive, the one aimed at the car ahead in the left lane, is substantially different from any lamp statute (“bright light law”) than the well-intended oncoming flash meant to warn a stranger about a speed trap.

One more provision deserves mention. Section 20-131(e) states that no city or town may enact an ordinance in conflict with the section. Charlotte, Matthews, Huntersville, and every other municipality in Mecklenburg County take their headlight rules from the General Assembly rather than writing their own.

Flashing Headlights to Pass on I-77, I-85, and I-485

Flashing headlights to pass is a familiar message on Charlotte interstates. You are in the left lane, a vehicle closes from behind, and the lights blink once or twice.

The message is ordinarily understood. That driver would like to pass and would like you to move right when you safely can.

It is a request. It is not a traffic-control signal, and the other driver acquires no authority over your lane by pulling the high-beam lever.

North Carolina law draws that line sharply, and the statute is worth reading closely because it says the opposite of what many drivers assume. N.C.G.S. § 20-149(b) provides that, except where overtaking and passing on the right is permitted, the driver of an overtaken vehicle shall give way to the right in favor of the overtaking vehicle while being lawfully overtaken on audible signal, and shall not increase speed until completely passed.

The duty in that subsection runs against the driver being passed, not the driver doing the passing. It is triggered by an audible signal, meaning a horn.

The graduated penalties in N.C.G.S. § 20-149(b) apply to failure to give way to the right while being lawfully overtaken on audible signal. The statute says the overtaken driver must give way to the right and not increase speed until the overtaking vehicle has completely passed. It then sets the penalties this way:

• Class 1 misdemeanor if the failure is the proximate cause of a collision resulting in serious bodily injury
• Class 2 misdemeanor if the failure is the proximate cause of a collision resulting in bodily injury or property damage
• Infraction in all other cases

So the General Assembly does attach legal weight to one overtaking signal. It attached that weight to the horn, which may seem somewhat odd nowadays.

A headlight flash is not an audible signal. Section 20-149(b) does not convert a flash into a statutory command, and the driver ahead does not commit an infraction by declining to move. Whether that driver independently should be in the left lane is governed by separate rules, which we cover in our article on North Carolina’s left-lane law.

Flashing Headlights to Warn of a Speed Trap

The question a lot of drivers actually search is whether flashing headlights to warn oncoming traffic about a patrol car is against the law.

Courts outside North Carolina that have addressed the question have treated the warning flash as expression rather than obstruction. In Elli v. City of Ellisville, 997 F. Supp. 2d 980 (E.D. Mo. 2014), a federal district judge entered a preliminary injunction barring a Missouri municipality from citing drivers who communicated with oncoming traffic by flashing their headlamps, finding the plaintiff likely to succeed on a First Amendment claim. The court observed that even assuming a driver was communicating a message to slow down because enforcement was ahead, that conduct was not illegal, and it declined the city’s suggestion that the flash amounted to interference with a police investigation.

Several points of restraint belong with that citation, and they are the reason a careful reader should be skeptical of any article that presents this as settled law in North Carolina.

Elli was a preliminary injunction rather than a final ruling on the merits. It came from a federal trial court in the Eastern District of Missouri, so it binds no court in North Carolina. It construed a municipal ordinance that specifically prohibited flashing signals, and North Carolina has no equivalent statute of that kind. In fact, the relevant NC law keeps local jurisdictions from enacting those types of statutes and vests such power in Raleigh, at the General Assembly.  No North Carolina appellate decision squarely decides whether a warning flash is protected expression.

What North Carolina does have is § 20-131, and that is where a citation would realistically come from. The warning flash is by definition aimed at oncoming traffic, which is precisely the situation the glare provision addresses. A driver who flicks the high beams at a car 300 feet away projects light onto a vehicle being met. A driver who intentionally keeps their bright lights on, thus temporarily “blinding ” the other driver, is a worse version of the same problem.

A separate theory, obstructing or delaying an officer under N.C.G.S. § 14-223, has been raised in other states and has not fared well. Encouraging another driver to comply with the speed limit is a strange fit for obstruction.

Realistic guidance is therefore somewhat narrow. The warning flash is unlikely to be charged in North Carolina, the constitutional arguments supporting it are substantial, and the exposure that does exist runs through the lamp statute rather than through obstruction.

The Optical Horn and What the Highway Code Says

The flash-to-pass custom did not come from a North Carolina statute. It comes from a driving convention in which light functions somewhat like a horn, sometimes called the optical horn.

The practice is associated with European highway driving, particularly on the German Autobahn, where traffic law formally recognizes sound and light warning signals for overtaking outside built-up areas. The gesture’s historical origin is not well documented, and it is fair to say it developed as driver-to-driver communication rather than as any official regulation.

The United Kingdom’s Highway Code sets forth an arguably sensible limit. Drivers should flash headlights only to let other road users know they are there. A flash of your bright lights does not confer right-of-way or tell another driver it is safe to proceed.

That is probably the right way to describe why folks flash their bright lights in Charlotte as well. It communicates. It does not command.

When Flashing Headlights Turns Into Aggressive Driving

A brief flash from a reasonable following distance is materially different from using high beams as a weapon.

Repeatedly blasting high beams from a few feet off another vehicle’s bumper communicates something other than a request, and the conduct surrounding it carries its own legal exposure. Following too closely is defined in N.C.G.S. § 20-152. Driving carelessly and heedlessly in willful or wanton disregard of the rights or safety of others, or without due caution under conditions then existing, is set forth in N.C.G.S. § 20-140.

Where a highway dispute escalates further, that legal analysis can depart from traffic law entirely. We covered that ground, including road rage allegations and how self-defense principles apply when a confrontation develops, in Camping in the Left Lane | Legal or Not So Much?

The driver requesting courtesy owes some in return. If the vehicle ahead cannot move immediately, backing off accomplishes more than escalating.

Moving Over Safely Is Still Your Call

Courtesy never requires an unsafe lane change.

If you are actively passing another vehicle, finish the pass before returning right. If weather, construction, debris, congestion, or another vehicle makes the movement unsafe, stay where you are until it is not. Do not jerk the wheel, cut in front of a vehicle you have not cleared, or drift into an occupied blind spot because someone is flashing lights at you.

When the right lane is open and the movement can be made safely, signal and move over. You are not conceding anything, approving anyone’s speed, or accepting fault. You are reducing the odds of a conflict neither driver needs.

The other driver’s speed is that driver’s responsibility. The safety of your lane change is yours. Your vehicle does not become an enforcement tool because someone behind you is in a hurry.

Flashing Headlights and North Carolina Traffic Law Questions

Do you have to move over if someone flashes their headlights?

Flashing headlights creates no duty to move right under North Carolina law. N.C.G.S. § 20-149(b) does impose a duty on an overtaken driver to give way to the right and to refrain from increasing speed, but that duty is triggered by an audible signal rather than by a light. Whether the driver ahead should be in the left lane at all depends on separate rules governing lane use and passing.

Where is traffic court in Charlotte?

Charlotte traffic matters, including lamp and equipment charges, are heard at the Mecklenburg County Courthouse at the cornder of McDowell and 4th Street, with most traffic cases first assigned to courtroom 1130. Our traffic violations FAQ covers what to expect on a first court date.

Talking With a Charlotte Traffic Ticket Lawyer

Most headlight “bright light” flashes never result in a traffic ticket citation. If it does, or when a flash is part of the story behind a following-too-closely charge, a reckless driving charge, or an accident, the question stops being about etiquette and becomes a matter with a court date, a statute, and a driving record behind it.

Bill Powers has practiced law in Mecklenburg County for more than thirty years. He is a former President of the North Carolina Advocates for Justice, a recipient of the North Carolina State Bar Distinguished Service Award, the author of the North Carolina DWI Quick Reference Guide, and a lawyer who regularly teaches continuing legal education on criminal law, evidence, and trial strategy.

Powers Law Firm handles Charlotte traffic tickets and criminal defense matters in the Charlotte metro area. For felony death by vehicle, felony serious injury by vehicle, misdemeanor death by vehicle, and select serious matters, statewide availability may be discussed.

If a traffic stop has left you with questions about your license, your insurance, or what is actually alleged on the citation, we may be available to help. Call or text 704-342-4357.