The sky shines a natural blue, so blue headlights must be legal, right? Not exactly. According to MarkVIII.org, blue headlights--and any headlight tint other than white--may not be used in the United States, Canada, Europe and Japan. Safety is the main concern behind these headlight regulations.
The U.S. National Highway Traffic Safety Administration (NHTSA) mandates that headlights in every U.S. state must emit only a white glow. This regulation comes from Federal Motor Vehicle Safety Standard 108, with the purpose of reducing traffic crashes, deaths and injuries; providing adequate illumination of the roadway; and enhancing the visibility of motor vehicles on public roads.
Transport Canada established Motor Vehicle Safety Standards 108 and 108.1 for regulating headlight use in the country. Standard 108.1 specifically says that headlights must emit a white light, according to the Society of Automotive Engineers (SAE) J578 color specification.
The Canada Motor Vehicle Safety Act further supports such regulations because of the many deaths that that have occurred on Canadian roads. Transport Canada notes that more people have died from Canadian motor accidents in the past 50 years than all Canadians killed in the two world wars.
The United Nations Economic Commission for Europe (UNECE) regulates the World Forum for Harmonization of Vehicle Regulations. As of 2010, 56 countries--both European and non-European--officially recognize UNECE headlight standards. These standards affirm that headlights must shine with white or "selective-yellow" light. The yellow light must be filtered of red and green colors according to specifications found in UNECE Regulation 8.
The Organization for Economic Cooperation and Development (OECD) notes that UNECE parties may adopt all or some of the regulations. For example, the U.S., although a UNECE party, has different headlight requirements from those of the UNECE.
MarkVIII.org emphasizes that while some tout blue headlamps as being improved lighting, these lights actually hinder visibility, since blue light incites pupils to close rather than open.
Additionally, any headlights sold in the U.S. with a "DOT Approved" marking should not be taken seriously since the U.S. DOT does not approve consumer products for use.
