Mr. Shlomo Zadok
Zadok Research Laboratories
739 North Occidental Blvd., Suite #6
Los Angeles, CA 90026

Dear Mr. Zadok:

This replies to your letter of July 25, 1996, asking for an interpretation as to the applicability of Federal laws to a "third brake light" that you have designed.

Federal Motor Vehicle Safety Standard No. 108 Lamps, Reflective Devices and Associated Equipment (Title 49 Code of Federal Regulations Sec. 571.108) is the Federal regulation that prescribes lighting equipment for new motor vehicles. Standard No. 108 refers to this item of equipment as a "center highmounted stop lamp" which is frequently abbreviated to "CHMSL." As Mr. Vinson explained to you in several phone talks on the subject, Standard No. 108 has required the CHMSL on all passenger cars manufactured on and after September 1, 1986, and on light trucks and vans manufactured on and after September 1, 1993. Both original and replacement CHMSLs for these vehicles must meet the requirements specified in Standard No. 108. Further, if you sell a CHMSL in the aftermarket for replacement of an original equipment CHMSL, you are required to certify that it meets the original equipment requirements, either by a DOT symbol on the lamp, or a statement on a label or tag attached to it or its container.

The unusual feature of your CHMSL is that it will carry a message in "big block letters" that don't flash or blink. Whether a "message" of this nature is permissible on original CHMSLs and their replacements depends on whether your CHMSL conforms to paragraph S5.1.1.27 of Standard No. 108. The most important of these requirements is that a CHMSL have an effective projected luminous lens area of not less than 4 square inches, that it have a signal visible to the rear through a horizontal angle from 45 degrees to the left to 45 degrees to the right of the vehicle's longitudinal axis, and that it have the minimum photometric values in the amount and location listed in Figure 10 of Standard No. 108 (the most difficult requirement to meet with a "message" imposed on the lens).

Your CHMSL as original equipment or its replacement is also subject to the prohibition of paragraph S5.1.3 that it not "impair the effectiveness" of any lighting equipment required by

Standard No. 108. This means that the message must not distract or confuse following drivers from reacting to the CHMSL and other stop signals exactly as they would were the message not there.

You also state that the CHMSL "is not so large as to block the driver's rear view." The Federal requirement is that, with the CHMSL in place, a vehicle must continue to conform to the rear field of view requirements of Safety Standard No. 111 Rearview Mirrors.

If you sell your CHMSL in the aftermarket as a replacement only for use on older vehicles that did not carry a CHMSL as original equipment, there is no Federal requirement that it comply with Standard No. 108. The sole Federal restriction is that a manufacturer, dealer, distributor, or motor vehicle repair business may not install the CHMSL if it " makes inoperative" any equipment originally installed to meet a Federal motor vehicle safety standard. We interpret this as meaning that your CHMSL must not detract from the stop signal provided by the two original equipment stop lamps, and that it must not create a noncompliance with Standard No. 111. Nevertheless, even if it meets these tests, your aftermarket CHMSL is subject to the laws of each state in which it will be used. We regret that we are unable to advise you on state laws, and suggest that you consult state Departments of Motor Vehicles.

Taylor Vinson will be pleased to answer any further questions you may have. You may call him at 202-366-5263.


John Womack
Acting Chief Counsel