NHTSA Interpretation File Search
Overview
NHTSA's Chief Counsel interprets the statutes that the agency administers and the standards and regulations that it issues. Members of the public may submit requests for interpretation, and the Chief Counsel will respond with a letter of interpretation. These interpretation letters look at the particular facts presented in the question and explain the agency’s opinion on how the law applies given those facts. These letters of interpretation are guidance documents. They do not have the force and effect of law and are not meant to bind the public in any way. They are intended only to provide information to the public regarding existing requirements under the law or agency policies.
Understanding NHTSA’s Online Interpretation Files
NHTSA makes its letters of interpretation available to the public on this webpage.
An interpretation letter represents the opinion of the Chief Counsel based on the facts of individual cases at the time the letter was written. While these letters may be helpful in determining how the agency might answer a question that another person has if that question is similar to a previously considered question, do not assume that a prior interpretation will necessarily apply to your situation.
- Your facts may be sufficiently different from those presented in prior interpretations, such that the agency's answer to you might be different from the answer in the prior interpretation letter;
- Your situation may be completely new to the agency and not addressed in an existing interpretation letter;
- The agency's safety standards or regulations may have changed since the prior interpretation letter was written so that the agency's prior interpretation no longer applies; or
- Some combination of the above, or other, factors.
Searching NHTSA’s Online Interpretation Files
Before beginning a search, it’s important to understand how this online search works. Below we provide some examples of searches you can run. In some cases, the search results may include words similar to what you searched because it utilizes a fuzzy search algorithm.
Single word search
Example: car
Result: Any document containing that word.
Multiple word search
Example: car seat requirements
Result: Any document containing any of these words.
Connector word search
Example: car AND seat AND requirements
Result: Any document containing all of these words.
Note: Search operators such as AND or OR must be in all capital letters.
Phrase in double quotes
Example: "headlamp function"
Result: Any document with that phrase.
Conjunctive search
Example: functionally AND minima
Result: Any document with both of those words.
Wildcard
Example: headl*
Result: Any document with a word beginning with those letters (e.g., headlamp, headlight, headlamps).
Example: no*compl*
Result: Any document beginning with the letters “no” followed by the letters “compl” (e.g., noncompliance, non-complying).
Not
Example: headlamp NOT crash
Result: Any document containing the word “headlamp” and not the word “crash.”
Complex searches
You can combine search operators to write more targeted searches.
Note: The database does not currently support phrase searches with wildcards (e.g., “make* inoperative”).
Example: Headl* AND (supplement* OR auxiliary OR impair*)
Result: Any document containing words that are variants of “headlamp” (headlamp, headlights, etc.) and also containing a variant of “supplement” (supplement, supplemental, etc.) or “impair” (impair, impairment, etc.) or the word “auxiliary.”
Search Tool
NHTSA's Interpretation Files Search
| Interpretations | Date |
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ID: aiam4995OpenMr. Gonshiro Miyoshi Manager, Design Administration Dept. Technical Division Ichikoh Industries, Inc. 80 Itado, Isehara-City Kanagawa, 259-11 Japan; Mr. Gonshiro Miyoshi Manager Design Administration Dept. Technical Division Ichikoh Industries Inc. 80 Itado Isehara-City Kanagawa 259-11 Japan; Dear Mr. Miyoshi: This responds to your letter of April 6, 1992, askin for an interpretation of Standard No. 108. With respect to a headlamp system consisting of two lamps, each containing two light sources, you have asked 'Is it permissible to have the bulb center of the lower beam lower than that of the upper beam (maximum height difference is 10mm) if they are arranged horizontally?' Paragraph S7.5(d)(2) specifies the manner in which 'the lower and upper beams of a headlamp system consisting of two lamps, each containing either one or two light sources, shall be provided . . .' In such headlamps where each light source provides a beam, the lower beam is provided 'by the outboard light source (or upper one if arranged vertically),' and the upper beam is provided 'by the inboard light source (or the lower one if arranged vertically).' Although the standard could be presumed to contemplate that two light sources within a headlamp would be located on the same horizontal or vertical plane, there is no specific requirement for light source placement. Because the difference in the horizontal mounting planes for bulb centers in your design is only 10mm, this difference is not sufficient to conclude that the light sources are vertically arranged, thus requiring that the lower beam bulb center be the 'upper' one, or on a plane that is higher. However, for your design to be permissible, the lower beam in this essentially horizontal array must be provided by the outboard light source in the headlamps as specified in S7.5(d)(2). Sincerely, Paul Jackson Rice Chief Counsel; |
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ID: aiam4353OpenMr. M. Arisaka, Manager, Automotive Lighting, Engineering Control Sect., Stanley Electric Co., Ltd., 2-9-13, Nakameguro, Meguro-ku, Tokyo 153, Japan; Mr. M. Arisaka Manager Automotive Lighting Engineering Control Sect. Stanley Electric Co. Ltd. 2-9-13 Nakameguro Meguro-ku Tokyo 153 Japan; Dear Mr. Arisaka: This is in reply to your letter of November 12, 1986, to former Chie Counsel Jeffrey Miller, concerning the photometric reference axis for a two lamp headlamp system, and location of aiming pads.; Your first question is what is the mechanical axis of performin photometry tests where the upper beam in a dual beam headlamp is provided by HB3 and HB4 light sources. As you know, the answer is simple for a single bulb sealed beam headlamp of symmetrical dimensions: a line perpendicular to the aiming plane through the geometric center of the lens (SAE Standard J579c). Thus, the reference axis for the lower beam of your system would be the geometric center of the portion of the lens that is illuminated by the HB4. The reference axis for the upper beam is not as easy to identify. Theoretically it should be the center of the light pattern that is produced by the two bulbs. This point would probably be somewhere between the midpoint of the axes of the HB3 and the HB4 and the axis of the HB3. This point is not shown on any of your drawings. However, since the intensity of the lower beam is usually less than 5000 cd at test point H-V, the theoretical point described above will be very close to the axis of the HB3. For this reason, the axis of the HB3 should be used as the reference axis for your system. In summary, your Case 1 Table A depicts the proper references axes.; You have also asked where the aiming pass ought to be located on such headlamp system, saying that NHTSA's interpretations letter of September 6.1985, indicated that the pads should be placed on the lower beam portion of the lamp's lens, but that lamps existed on which they were placed elsewhere. Our 1985 letter was written at a time when experience with these lamps was limited. We now believe that the pads can be located anywhere that will permit proper mechanical aiming, proper reference for photometric purposes, and that do not interfere with the forming of the beam. Therefore, either of the two locations you present, or any other location, is acceptable provided that the three conditions mentioned above are met.; I hope that this answers your questions. Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam4528OpenThe Honorable Douglas H. Bosco House of Representatives Washington, DC 20515; The Honorable Douglas H. Bosco House of Representatives Washington DC 20515; Dear Mr. Bosco: This is in reply to your letter of June l6, l988, wit reference to your constituent Jerry Yost of Occidental. Thank you for enclosing our previous correspondence on Mr. Yost's C-More Light invention. This device is a relay which would allow a headlamp's lower beam to remain in operation when the upper beam is activated. In my reply of August 3, l987, I advised you that the Federal motor vehicle lighting standard explicitly prohibits simultaneous activation of upper and lower beams in four-lamp headlighting systems other than the one we call Type F (S4.5.8 of 49 CFR 57l.108 Motor Vehicle Safety Standard No. 108). I explained that our historical concern has been that the maximum candlepower limitations of the Federal standard might be exceeded. In your latest letter, you have enclosed a copy of a test report by Industrial Testing Laboratories and a letter from the California Highway Patrol. You have asked the steps, if any, that Mr. Yost should take to market legally his device. The test report is intended to show that maximum candela will not be exceeded when the device is used in a four-lamp headlamp system. California advised that the device appeared legal to install on vehicles equipped with Type F headlamp systems, and that 'this system is also permitted by California law as long as the photometric output is within the standards established for any other type of headlight. The ITL tests appear to show compliance'. We have reviewed the ITL test report, and find it indicative of the features and limitations of Mr. Yost's system. The test report shows a failure of the dual filament 2A1 lamp (second column from the left) at test point 4D-V where 3490 candlepower is measured. Note the maximum limitation of 2500 candlepower at that test point (third column from the right, same line). Contrasted with this is an unusually low reading of 2540 candlepower for the same test point with the single filament 1A1 lamp (third column from the left) when up to 5000 candela is allowed (fourth column from the right). The net result, however, is that the combined maximum of 6030 candlepower (fourth column from the left) is well within the allowable 7500 maximum of Standard No. 108 (first column from the right). In essence, the test report indicates that the light at test point 4D-V produced by the system under test does not achieve the balance contemplated by the standard, although the light at other test points meets the requirements of the standard. While the test report indicates that a system using the lamps tested might conform to Standard No. 108, this was achieved by using what appear to be two lamps of moderate performance. The agency believes it likely that replacement headlamps for such a system would more likely approach the maxima prescribed for 4D-V and other test points for Type 1A1 and 2A1 headlamps with the result that simultaneous operation of upper and lower beams would exceed the established limits. In other words, although an original equipment headlighting system using the relay might meet Federal photometric specifications, there is no assurance that replacement lights would. Type F systems have been designed to preclude exceeding the maxima. Thus, our concern remains for lighting systems using lamps other than Type F. The agency's views on simultaneous operation are discussed in further detail in a Federal Register notice published in l986, a copy of which I enclose (Docket No. 81-11, Notice l4). As I indicated before Mr. Yost's device may be legally installed as original or aftermarket equipment on any passenger car equipped with a Type F headlamp system. Use with any other original equipment headlighting system is expressly prohibited by Standard No. 108. As for aftermarket applications other than Type F, he should be aware of the statutory section (15 USC 1397(a)(2)(A)) prohibiting manufacturers, distributors, dealers, and motor vehicle repair businesses from rendering inoperative, in whole or in part, any equipment installed in accordance with a safety standard if installation of the relay would result in a noncompliance with Standard No. 108. We are providing a copy of this letter to the California Highway Patrol so that it may be aware of our views on this subject. Mr. Yost and the agency share a common desire to improve foreground lighting, a subject currently under study at NHTSA. We appreciate his interest in motor vehicle safety. Sincerely, Erika Z. Jones Chief Counsel Enclosure cc: Department of California Highway Patrol P.O. Box 942898 Sacramento, CA 94298-0001; |
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ID: aiam0768OpenMr. F. Michael Petler, Assistant Manager, Product Development Department, U.S. Suzuki Motor Corporation, 13767 Freeway Drive, Santa Fe Springs, California 90670; Mr. F. Michael Petler Assistant Manager Product Development Department U.S. Suzuki Motor Corporation 13767 Freeway Drive Santa Fe Springs California 90670; Dear Mr. Petler: This is in response to your letter of July 11, 1972, asking whethe Suzuki switches 577-2 and 577-5 comply with the headlamp beam operational requirements of Standard No. 123.; We assume that the letters 'L' and 'H' on each switch means 'low beam and 'high beam' respectively. Each switch has two positions, the upper on each marked 'L' and the lower marked 'H'. Standard No. 123, as you have noted, requires that a headlamp beam control switch provided an upper beam by pushing up, and a lower beam by pushing down. You have commented that 'in their current state of design these headlamp beam switch functions are the opposite as specified in Standard No. 123.'; Thus, as you appear to have surmised, switches 577-2 and 577-5 do no meet the headlamps beam operational requirements of Standard No. 123.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam0125OpenMr. D. W. Nurse, President, Heath Company, Benton Harbor, MI 49022; Mr. D. W. Nurse President Heath Company Benton Harbor MI 49022; Dear Mr. Nurse: This is in response to your letter of November 13 with regard to th applicability of Federal motor vehicle safety standards to the GT-18 Trail Bike kit, and the 'Boonie-Bike' assembled from it.; I am unable to tell from your letter the exact nature and use of th Boonie-Bike but I will assume that it is an off-the-road special purpose motorcycle designed for recreational use. Such a machine is a 'motor vehicle' for purposes of the National Traffic and Motor Vehicle Safety Act of 1966 since, like a multipurpose passenger vehicle, it is equipped with special features for off-road use but is capable of being operated both on and off the public roads. Thus it is not correct to say that trail bikes have not been considered motor vehicles in the past. The interpretation to which you refer, incidentally, if it appears, will be directed toward the so-called 'mini-bikes'.; Accordingly, it is possible to confirm your understanding that: >>>'...for the purposes of the National Traffic and Motor Vehicl Safety Act of 1966, Heath's responsibility is limited to insuring that any kit item which it supplies to which a Federal Safety Standard is directly applicable (i.e., only glazing materials at the present time) shall meet such Safety Standards, and inasmuch as Heath does not build the kits or perform the actual conversion, it is not a manufacturer of motor vehicles and consequently not responsible for the entire assembled product.'<<<; Since a Boonie-Bike is equipped with a '5-brake horse power Briggs an Stratton 4-cycle engine' it is sub-classified as a 'motor-driven cycle' which is defined as 'a motorcycle with a motor that produces 5-brake horsepower or less'.; As you infer Federal Standard 108 will apply to motorcycle manufactured or assembled on or after January 1, 1969. Motorcycles are required to be manufactured with one white headlamp in accordance with SAE Standard J584 (Motorcycle and Motor Driven Cycle Headlamps). This SAE Standard allows a motor driven cycle to be assembled with either a single or multiple beam headlamp. Consequently a motor driven cycle assembled with a single beam headlamp is not subject to paragraphs S3.4.1 and S3.4.2 of Federal Standard No. 108 requiring provision of a headlamp beam switch and indicator.; I hope this answers your questions. Sincerely, Robert M. O'Mahoney, Assistant Chief Counsel for Regulations |
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ID: aiam4727OpenMs Margaret Schmock Dept K2/ELE2 Robert Bosch GmbH Postfach 42 7410 Reutlingen W. Germany; Ms Margaret Schmock Dept K2/ELE2 Robert Bosch GmbH Postfach 42 7410 Reutlingen W. Germany; Dear Ms Schmock: This is in reply to your FAX of March 6, l990, wit respect to the relationship between Federal Motor Vehicle Safety Standard No. 108, and 'CAC Title 13, Article 9'. You have indicated that CAC requires a headlamp adjustment range in the horizontal of at least +/- 4 degrees, whereas Standard No. 108 requires a horizontal adjustment range of not less than 2.5 degrees. You have asked whether Bosch headlamps still must have an adjustment range of +/-4 degrees in the horizontal although Standard No. 108 has been changed. We understand that 'CAC' refers to 'California Administrative Code'. The effect of the preemption provisions of the National Traffic and Motor Vehicle Safety Act is to prohibit California from adopting and enforcing a minimum horizontal headlamp adjustment range greater or less than 2.5 degrees. Thus, a State requirement that a headlamp have a horizontal range of +/- 4 degrees is invalid because it differs from a corresponding Federal requirement. We are unable to answer your further questions with respect to the California code, and suggest that, for further information you write Department of Motor Vehicles, State of California, 2415 First Avenue, Sacramento, California 95818, ATTN: Mr. A. A. Pierce, Director (FAX 916-732-7854). Sincerely, Stephen P. Wood Acting Chief Counsel; |
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ID: aiam2595OpenMr. James R. Green, 3396 Alma Street, Lynwood, CA 90262; Mr. James R. Green 3396 Alma Street Lynwood CA 90262; Dear Mr. Green: Your letter of April 8, 1977, to the President of the United State concerning the need for improved motor vehicle headlamp standards has been referred to this office for consideration and reply.; We have received considerable information regarding the effects o foreign and domestic motor vehicle headlighting equipment, including engineering papers and test data on 'selective yellow' headlamps. All information concluded that filtering of headlamps to produce yellow reduces the photometric intensity of the lamp, thereby reducing the actual seeing distance. Some vehicle operators subjectively concluded they can see further with yellow headlamps, but objective seeing distance tests with specific target characteristics and distances indicate a loss of seeing distance.; It is also true that while the original intent in using yello headlamps was to reduce the glare from oncoming vehicle headlamps, our current test data indicates that a yellow light does not reduce glare. The white light is, therefore considered safer and is the basis for requiring white light in Federal Motor Vehicle Safety Standard No. 108 (copy enclosed).; Although this lighting standard is generally in accordance wit standards developed and published by the Society of Automotive Engineers, it does not specifically require sealed-beam headlamps. However, it does require headlamps which are designed to be aimed properly when installed in prealigned mechanical assemblies. The lamp itself may be sealed-beam (filament is enclosed only by the lamp shell in an inert atmosphere) or it may be a halogen lamp (filament is surrounded by a small envelope containing a halogen gas). Specifically, the halogen-bulb headlamp is legal if incorporated into an otherwise legal motor vehicle headlamp.; I trust the foregoing is fully responsive to your inquiry. Sincerely, E. T. Driver, Director, Office of Crash Avoidance, Moto Vehicle Programs; |
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ID: aiam4359OpenMr. M. Iwase, Manager, Technical Administration Dept. Koito Mfg., Ltd., Shizuoka Works, 500, Kitawaki, Shimizu-Shi, Shizuoka- ken, Japan; Mr. M. Iwase Manager Technical Administration Dept. Koito Mfg. Ltd. Shizuoka Works 500 Kitawaki Shimizu-Shi Shizuoka- ken Japan; Dear Mr. Iwase: This is in reply to your letter of March 24, 1987, asking two question with respect to Motor Vehicle Safety Standard No.108; Your first question concerns an aiming adaptor for replaceable bul headlamps whose lenses may slant 60 degrees from the vertical or horizontal. You have discovered that the Hopkins universal adaptor cannot be used with these headlamps, and you propose to provide a special adaptor with each vehicle equipped with such headlamps, as well as aiming adjustment procedure information in the vehicle's service manual. You ask for confirmation of your belief that this is permissible under Standard No. 108.; Standard No. 108 does not require that an aiming adaptor be provide with a motor vehicle, only that its headlamps be capable of mechanical aim. Therefore there is no legal requirement that the adaptor be provided. However, without such an adaptor, an owner of a vehicle with the 60-degree headlamps may encounter difficulties of State inspection stations where mechanical aimers are in use, and at repair facilities when headlamps are replaced or after body work has been performed that necessitates reaim of headlamps. Therefore we believe that provision of the adaptor and aiming information would enhance consumer acceptance of the 60- degree headlamps.; Your second question concerns the legality of the upper aiming boss o a low profile headlamp. Because the height of the lens is insufficient to incorporate the upper aiming boss, you propose to place it on a flange of the lens in a 'photometrically ineffective area.' However, the flange is concealed when the hood is shut, and the hood must be opened in order for aiming adjustment to occur. You believe that this is acceptable under Standard No. 108. and ask for confirmation.; Paragraph S4.1.1.36 (a)(2) requires that 'the lens of each replaceabl bulb headlamp shall have three pads which meet the requirements of Figure 4....' Your drawing indicates that the flange is part of the headlamp lens even though that portion of the lens is not needed to provide illumination. Therefore this design would appear to meet the requirements of Figure 4 as you have concluded.; Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam4764OpenMr. William Waltz Wagner Division Cooper Industries, Inc. 155 Algonquin Parkway Whippany, NJ 07981; Mr. William Waltz Wagner Division Cooper Industries Inc. 155 Algonquin Parkway Whippany NJ 07981; Dear Mr. Waltz: This is in reply to your letter of April 12, l990 stating that Wagner Division 'would like to petition N.H.T.S.A. for a 'Determination of Inconsequentiality' for non-compliance.' Specifically, Wagner wishes to manufacture round sealed beam headlamps (not 'bulbs' as you call it) for Lectric Limited, a small parts business geared towards the antique automobile hobby. The headlamps are intended for use on 'antique automobiles'. We understand that term to mean any automobile manufactured in l940 and subsequent model years that was originally equipped with round sealed beam headlamps. Although the headlamps would be designed to conform to current specifications, those of SAE Standard J579c, the word 'top' would be used on the 7-inch diameter headlamp instead of the designation '2CI' (you mean '2D1'), the numeral '1' for '1C1' on the single beam 5 3/4-inch diameter headlamp, and the numeral '2' for '2C1' on the dual beam 5 3/4-inch diameter headlamp. The lamps would not bear 'DOT' identification. Lectric Limited is willing to 'ink stamp' DOT, 2Dl, 1C1, and 2C1 'on either the face and or the rear' of each headlamp so that they would not be mistaken for those conforming to SAE J579a, and to print instructions for purchasers explaining the difference. Lectric Limited is also willing to insure that the headlamps are marketed only through antique auto specialty retailers. First, let me explain that your request cannot be considered as one for a determination of inconsequentiality. These determinations are made after-the-fact in order to determine whether a manufacturer must fulfill statutory obligations which include replacement, repurchase, or repair of the already-manufactured noncompliant product. What you seek is permission to produce motor vehicle equipment that fails to comply with labeling requirements. Unfortunately, the agency has no exemption provisions which can address this issue. We have authority to exempt manufacturers of motor vehicles from compliance for a temporary period, but we have no authority to exempt manufacturers of motor vehicle equipment, on either a temporary or permanent basis. Further, we cannot waive the marking requirements of sections S7.2 and S7.3 of Standard No. 108, even for the limited purpose and subject to the restrictions you discuss. After due consideration of the matter, we believe that you have no choice other than to conform to the marking requirements of Standard No. 108. Although neither the marking nor the performance of J579c headlamps replicates that of J579a headlamps, I hope that auto enthusiasts will be willing to accept the marking that goes with the improved performance. Sincerely, Paul Jackson Rice Chief Counsel; |
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ID: aiam5210OpenMr. Charles Jennings 1330 Heathwick Lane Houston, TX 77043; Mr. Charles Jennings 1330 Heathwick Lane Houston TX 77043; "Dear Mr. Jennings: This responds to your letter received in thi Office on July 2, asking for an opinion of your invention, the Alternating Wavelength Low-Beam (AWL). The AWL 'connects to the already existing low beam headlights, by just plugging it between the electrical sockets and the lights.' The effect of the device is to create 'light modulations of less than 17 per second, alternating from one of the two existing low-beam headlights to the other, and at the same time, changing wavelengths slightly, from one to the other (not flashing on and off).' We have no opinion on the safety merits of your invention but can provide you with an interpretation of its relationship to Federal law. The AWL appears intended as an aftermarket device. There are no Federal restrictions on the sale of this device. Nor is there any Federal restriction upon installation of the AWL when it is installed on a vehicle by its owner. Such an installation appears a distinct possibility from your brief description of it. At this point, the question of the legality of its use is determined under the laws of the States where the AWL is operated. You represent that its operation in Texas is acceptable to the Department of Public Safety. However, this opinion would not be binding on other States. We are unable to advise you on the legality of using the AWL in the various States and suggest that you ask for an opinion from the American Association of Motor Vehicle Administrators, 4600 Wilson Boulevard, Arlington, VA 22203. However, the National Traffic and Motor Vehicle Safety Act (the Act) prohibits most persons other than the owner (specifically, manufacturers, distributors, dealers, and motor vehicle repair businesses) from acts that may 'knowingly render inoperative', in whole or in part, safety equipment that the vehicle manufacturer has added pursuant to a Federal motor vehicle safety standard. The lower-beam headlamps are original equipment installed by the vehicle manufacturer under Federal Motor Vehicle Safety Standard No. 108 Lamps, Reflective Devices, and Associated Equipment. Standard No. 108 requires headlamps to be steady-burning in use, though means may be provided to flash them on and off automatically for signalling purposes. Because the modulation created by the AWL results in a headlamp beam that is neither steady burning nor an on-off signal flash, the vehicle's headlamp system would no longer be in compliance with Standard No. 108. In our view, the headlamp system's performance would have been rendered partially inoperative within the meaning of the Act's prohibition when the AWL is sold in the aftermarket and installed by a manufacturer, distributor, dealer, and motor vehicle repair business. The Act provides for a civil penalty of up to $1,000 for each violation of the prohibition. We hope that you find this information useful. Sincerely, John Womack Acting Chief Counsel"; |
Request an Interpretation
You may email your request to Interpretations.NHTSA@dot.gov or send your request in hard copy to:
The Chief Counsel
National Highway Traffic Safety Administration, W41-326
U.S. Department of Transportation
1200 New Jersey Avenue SE
Washington, DC 20590
If you want to talk to someone at NHTSA about what a request for interpretation should include, call the Office of the Chief Counsel at 202-366-2992.
Please note that NHTSA’s response will be made available in this online database, and that the incoming interpretation request may also be made publicly available.