World Harmonization and Procedures for Lighting and Signaling Products 970913
Lighting and signaling regulations vary considerably around the world. There are 3 main regulatory regions: the United States, Europe and Japan. Rules vary in scope as well as in strictly technical requirements. The ECE has published the most comprehensive regulations, covering even headlamp leveling and cleaning devices. Japan has, for the time being, the least extensive ones.
Standard lamp Regulations are pretty much alike, with the center high mounted stop lamp being the most notable exception. The most pronounced differences are for headlamps: all values above the horizon line are lower in Europe where being dazzled is not accepted. The cutoff line is also sharper in Europe, where visual aim has been common practice for 70 years.
Europe specifies amber rear side markers and amber rear turn signals but prohibits red contour markings as well as rear turn signals and red rear side markers.
Differences are more acute in the field of procedures. In the US, components are not subject to previous approval by the authorities as in Europe. The NHTSA checks a posteriori the compliance of those products which have caused complaint or damage, but the general rule consists of trusting the automobile manufacturer as long as no adverse event has occurred.
Those manufacturers who need to export have to pay high costs for tool duplication and administration. The rationale for this is not quite convincing since one has to admit that each country is consistent on its own territory.