[Poochie]

Originally Posted by J-RO

Thanks for the explanation. Who makes up all these crap regulations?

This law has been in effect in the USA (and Canada) since 1960s by the National Highway Traffic Safety Administration (US DOT) and they had the best intentions at the time.

Back then, many vehicle models had very small tail lights, which could be hard to see until you were literally right up on them and the taillight's plastic/color quality of that time, had a tendency to fade over a shorter period, so the US governing bodies forced automakers to design bigger tail light assemblies, which were more visible to other drivers, by legislating a minimum size requirement, across the board.

The size requirement is based on a concept called EPLLA (Effective Projected Luminous Lens Area), which states that the minimum illuminated size of a rear turn signal (or brake light) must be at least 50 cm squared (or 7- 3/4 in squared). If this size requirement is not met, then automakers are forced to change the rear turn signals in order to comply.

With the advent and complacency of LEDs lights and better quality plastic technology, its bright intensity makes the larger size requirement moot. However, since the laws was never revised to incorporate modern lighting technology, taking brightness into consideration, instead, the old US law concentrates primarily on minimum illuminated size of the brake light and turn signal, forcing manufacturers to adapt to the older requirement, even with jarring bright LED lights of today, thus, sometimes having to develop two separate taillights, for each region.