How to Legally Upgrade and Customize Your Vehicle Lighting

The laws regarding upgrades to headlights, taillights, underglow, and other light mods.

Federal and state laws require highway vehicles to have certain types of lighting. Generally, these requirements are based on safety concerns.

Along with lighting requirements, the law also imposes limits on how bright and luminescent a vehicle can be. Additionally, there are restrictions on the colors of vehicle lights.

There are many aftermarket modifications available for your vehicle, but not all of them are legal in different states. This article will give you an overview of the different types of modifications and how to keep your vehicle street-legal.

Legal Restrictions on Car Headlights

Headlights are the brightest lights on the vehicle, but also the most restricted. Federal regulations require headlights to specifically be white or amber. The white and amber lights are generally considered the best colors to ensure visibility.

Are LED Headlights Legal?

People often want to know whether LED lights are legal. Restrictions don't typically deal with the specific type of lights. However, there are limits on how bright headlights can be.

Most states tend to follow federal regulations regarding bulb luminosity. The regulations specify the legal number of candelas as measured from a specific geometric point on the bulb. But most people don't know what a candela is, nor do they wish to calculate geometric positions. To simplify things, the Department of Transportation tests and certifies manufactured bulbs. As long as the headlight is labeled DOT or SAE approved, it is legal in the United States.

Are "Blue" Headlights Legal?

Xenon and high-intensity discharge (HID) lights are often DOT-approved and road-legal, even though they may appear to be blue to the naked eye. However, the lights are actually such a pure white that our eyes perceive them as blueish. As long as the bulbs are DOT-approved and do not exceed local brightness laws, they are legal to install.

Are There Other Restrictions on Headlight Colors?

To prevent other drivers from being confused with an emergency vehicle, it is generally illegal to have any color of light—other than amber or white—visible from the front of the vehicle. Many after-market products are available to modify headlights and the vehicle front, including halos and demon-eyes. While these modifications may be legal in theory, displaying any color other than amber or white can result in a violation.

Are Roof or Overhead Light Bars Legal?

Roof lights are typically subject to the same limitation as headlights regarding color and luminosity. However, many states do limit the number of roof lights to prevent blinding oncoming traffic.

Are Spotlights Legal?

In some states, there are restrictions on the use of auxiliary spot lamps. These restrictions often limit spotlights to a certain range or require that they only point forward.

Legal Restrictions on Taillights

The rules that apply to taillights are similar to those that apply to headlights. Taillights can technically be customized but must still serve the specific function.

What Types of Taillights Must a Vehicle Have?

Every vehicle must have two brake lights, two taillights, and a small tag light to illuminate the license plate. However, the brake lights can be LED and of different shapes. Vehicles are also permitted to have backup lights (white or amber) that activate while in reverse as well as truck-bed lights that illuminate the bed of a pickup truck.

What Colors of Taillights are Legal?

Taillights and brake lights typically must be red. Except for the taillights and brake lights, drivers can't have any off-color lights visible from the rear of the vehicle. Again, the rule ensures distinction from emergency vehicles.

How Bright Can Taillights Be?

Taillights are similarly subject to the same federal brightness regulations. It is best to purchase DOT-approved brake and taillights.

Are Car Underglow Lights Legal?

Due to the restrictions on headlights and taillights, many car enthusiasts choose to demonstrate their radiance from under the car. As a relatively newer development, few states have specific laws for underglow lighting.

Off-color Lighting Laws

While most states don't have specific laws regarding underglow, other restrictions apply. As most states prohibit off-color lights from being seen from the front of the vehicle, off-color underglow lights generally aren't permitted if they can be seen from the front of the vehicle.

As the rule is intended to protect oncoming traffic, underglow lights that are only visible up close or by looking underneath the car, are normally legal.

States that Have Underglow Laws

Of the states that do have specific laws regarding underglow, most require that the bulbs be hidden under the vehicle and prohibit the use of red or blue lights (as these colors can lead to confusion with emergency vehicles).

In some other states, there are restrictions on the brightness of the underglow (four candelas in Vermont and distance visibility (75 feet in Alabama).

Strobe Light Restrictions

In most states, strobe or flashing lights are prohibited anywhere on a vehicle. This restriction also applies to underglow and neon lighting.

Vehicle Interior Light Restrictions

Although less of a problem, lights inside of the car are still subject to the same general limitations as those that apply to outside lighting. In other words, interior lights can't violate the color or brightness limitations discussed above.

A few states have laws that specifically address interior lights. For example, California law permits diffused LED lights to be affixed to the inside of the windows so long as they aren't red or more than .25 candela.

Vehicle Lighting Tickets and Penalties

Light violations are often obvious to police and can lead to a traffic citation. When you get a lighting ticket, you'll typically have to pay a fine (normally, less than $50) and remove the unlawful light modification.