When driving down the road, it is imperative that brake lights ahead are functioning so that all travellers can stop accordingly as the traffic slows. A third brake light is mandated by law.
The third brake light is normally centred and placed higher than the two typical brake lights below that flank the vehicle. Adding this third light captures the line of sight of the drivers following the car, as opposed to the use of just two lights, making the braking reaction faster.
Federal law mandates that all vehicles have the third brake light outfitted within the car. Additionally, the third light must be comparable to the other brake lights on the vehicle so that it is not distracting to the drivers behind the vehicle.
The third brake light law went into effect in 1986 for passenger cars, and light trucks in 1994. The decision was based on effective tests done with taxi cabs and company fleet vehicles, illustrating a reduction in rear end crashes with the use of the extra light.