SAE vs DOT: The Truth About Lighting Regulations

Distinguishing each agency and its responsibilities

August 11, 2016 @ 1:22 PM Tech Article

First, let's define some terms:

SAE – The Society of Automotive Engineers is a U.S.-based, globally active professional association and standards organization for engineering professionals in various industries. Principal emphasis is placed on transport industries such as automotive, aerospace and commercial vehicles. SAE International coordinates the development of technical standards. The technical standards are based on best practices as identified and described by SAE committees and task forces who are experts in their fields. 

DOT – The United States Department of Transportation is responsible for the issuance of safety standards like the Federal Motor Vehicle Safety Standard 108 (FMVSS-108), which applies to lighting.

There is a great deal of confusion regarding lighting regulations in the industry. One common mistake is using the term "DOT approved." The United States Department of Transportation is not an approval agency and will not approve products. In the past, USDOT has sternly warned manufacturers that claim that their products are "DOT approved;" the correct language is "DOT compliant."

In the US and Canada, lighting products are certified by the lighting manufacturer as compliant, and unless the certification is "clearly erroneous," the certification will stand. The reputable manufacturer will state that its products are "designed to conform" to the elements of the FMVSS-108 requirements. 

Some of the misuse of terminology stems from the fact that there are three products that must be marked with the "DOT" symbol: headlights, replaceable bulbs for headlights and reflective tape.

SAE standards are often referred to as "recommended practices," which provide a basis for a particular function. The SAE standard can create a common method and performance level for a specific lighting function. SAE standards may be referenced and become part of the law in some cases, which also causes confusion. 


The DOT or Federal Regulations will preempt or take precedence over the state regulations when both regulations exist. For example, there is no federal regulation for fog lamps, so the state regulations are in effect. Fortunately, the states have settled on calling out the SAE J583 Fog Lamp Recommended Practice, so that is why there is no federal standard. 

The area of auxiliary lamps on vehicles is another confusing part of the regulations. The good news is that auxiliary lighting in general is allowed for installation on vehicles. The one important condition is found pursuant to 49 U.S.C. 30122: if equipment is installed by a manufacturer, distributor, dealer or motor vehicle repair business, that equipment, as installed, must not make inoperative any of the required safety equipment. If an item of equipment impairs the effectiveness of the lighting equipment required by FMVSS-108, we consider the installation of such equipment to have rendered the lighting systems partially inoperative. 

Consulting with Truck-Lite engineering and technical support departments is often the best way to ensure that your insallation complies with the federal requirements and does not impair the effectiveness of any of the required devices.

Truck-Lite Technical Support can be reached by email at or by phone at (888) 562-5012 to assist with any questions.