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
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ID: aiam0091OpenMr. Warren M. Heath, Commander, Engineering Section, Department of California Highway Patrol, P.O. Box 898, Sacramento, CA 95804; Mr. Warren M. Heath Commander Engineering Section Department of California Highway Patrol P.O. Box 898 Sacramento CA 95804; Dear Mr. Heath: Thank you for your letter of July 2, 1968, to Mr. George C. Nield Acting Director, Motor Vehicle Safety Performance Service, concerning requirements for combination clearance and side marker lamps.; Paragraph S3.3 of Motor Vehicle Safety Standard 108 permits th combination of two or more lamps providing the requirements for each are met. Table I in SAE Standard J592b gives the photometric requirements for both the clearance and side marker lamps, and Section J of the Standard permits their combination providing the combination complies with both clearance and side marker minimum candlepower requirements. Section J also defines the H-V axis of the combination as parallel with the longitudinal axis of the vehicle when checking clearance lamp test points, and normal to this vehicle axis when checking side marker test points.; Your table of minimum candlepower requirements for the Type combination lamp meets J592b and therefore Standard No. 108 providing you define the H-V axis as that of the side marker lamp. The requirements for the Type 1 combination as specified in your table will not meet J592b or Standard No. 108 unless you change H-10, -20, -30, -45, -60, - 80 and -90, both L and R to H-15, -25, -35, -45, -55, -65, -75 and -90, both L and R, and define the H-V axis as a line through the center of the lamp at a 45 degree angle to the longitudinal axis of the vehicle.; Your mounting instructions are considerably more restrictive than thos implied in J592b and Standard No. 108. Actually, no additional mounting instructions are necessary, because any mounting which meets the minimum candlepower requirements of Table I in J592 and your table with the suggested revisions would meet the requirements of Standard No. 108.; Sincerely, David A. Fay, Office of Standards on Accident Avoidance Motor Vehicle Safety Performance Service; |
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ID: aiam1759OpenMr. Hans von Payr, General Manager, VDO Instruments, 116 Victor Avenue, Detroit, Michigan 48203; Mr. Hans von Payr General Manager VDO Instruments 116 Victor Avenue Detroit Michigan 48203; Dear Mr. von Payr: This is in reply to your letter of December 26, 1974 asking question about Motor Vehicle Safety Standard No. 123, *Motorcycle Controls and Displays*.; Standard No. 123 applies to motorcycles, and the manufacturer of th completed vehicle is responsible for compliance with the standard. The standard does not include items manufactured for the aftermarket. Under an amendment to the National Traffic and Motor Vehicle Safety Act of 1966 that became effective late in December 1974 a dealer may not 'render inoperative', *e.g.* remove, equipment installed by the manufacturer that has been installed in compliance with a standard. There would be no objection, however, if a dealer removed an originally installed speedometer and replaced it with one that also met the Federal requirements.; The date of applicability of a standard is the date the vehicle wa manufactured, not the date it is sold. Therefore non-complying motorcycles manufactured before the effective date of Standard No. 123 - September 1, 1974 - may be sold after that date. The standard applies to those motorcycles manufactured primarily for use on the public roads, and not to mini-bikes, trail bikes, ATVs, or other non-licensed vehicles intended for off-road use.; Standard No. 123 does not require a specific size for numerals, onl that 'Major graduations and numerals appear at 10 mph intervals, minor graduations of the 5 mph intervals' (Column 3, Table 3). With respect to your paragraphs a) and b) on page 3 of your letter, elimination of any speed indication at the required 10 mph intervals would result in a noncompliance of the cycle on which the speedometer was mounted. Since your enduro and chopper speedometers are marked only at 20 mph intervals they do not meet the requirements of Standard No. 123 for original motorcycle equipment.; Yours truly, Richard B. Dyson, Acting Chief Counsel |
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ID: aiam4111OpenMr. Marshall D. Carter, Whisper Electric Car AS, 87 Hadsundve, Als, DK-9560 Hadsund, Denmark; Mr. Marshall D. Carter Whisper Electric Car AS 87 Hadsundve Als DK-9560 Hadsund Denmark; Dear Mr. Carter: This is in reply to your letter of February 18, 1986, asking tw questions with respect to the Federal motor vehicle safety standards.; With respect to electric vehicles, you have asked 'is there a standar regulating the minimum length of time that the hazard light must be able to function at a minimum intensity, on the service battery alone?' There is no such standard. The vehicle must be equipped with a hazard warning signal operating unit designed to conform to SAE J910, January 1966, and a hazard warning signal flasher designed to conform to SAE J945, February 1966, but there is no requirement in the Federal motor vehicle safety standard on vehicle lighting, Standard No. 108, that the hazard warning signal flashers perform for a minimum specified period of time in service.; You have also asked 'Is there a requirement that the vehicle b equipped with an illuminated display, indicating gear selection?' We are unable to confirm your conclusion that there is no such requirement under Standard No. 101. Paragraph S3.2 of Standard No. 102 requires that identification of shift lever positions or patterns be permanently displayed in front of the driver. Paragraph S5.3.1 of Standard No. 101 requires illumination of the 'gauges' listed in Column 1 of Table 2 that are accompanied by the word 'Yes' in Column 5. The last 'gauge' listed is 'Automatic gear position', and the word 'Yes' appears in Column 5. The automatic gear position is a 'gauge' as defined by paragraph S4 of Standard No. 101, 'a display that is listed in ...Table 2 and is not a telltale'. Thus the Federal standards do require illumination of the gear positions of automatic transmissions, but not of manual ones.; I hope that this responds to your questions. Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam5124OpenMr. Frank E. Timmons Rubber Manufacturers Association 1400 K St., N.W. Washington, DC 20005; Mr. Frank E. Timmons Rubber Manufacturers Association 1400 K St. N.W. Washington DC 20005; "Dear Mr. Timmons: This responds to your letter about our November 199 letter to the Under Secretary, Kuwait Ministry of Commerce. In that letter, NHTSA discussed Federal requirements for tires sold in the United States for passenger cars and other 'motor vehicles.' You wish to ensure that the Under Secretary understands that the term 'motor vehicles' only refers to vehicles 'manufactured primarily for use on highways.' We are glad to clarify the meaning of the term 'motor vehicle.' 'Motor vehicle' is defined in 102(3) of the National Traffic and Motor Vehicle Safety Act as 'any vehicle driven or drawn by mechanical power manufactured primarily for use on the public streets, roads, and highways, except any vehicle operated exclusively on a rail or rails.' (Emphasis added.) Thus, a motor vehicle is a vehicle that the manufacturer expects will use public highways as part of its intended function. This agency has issued many interpretations of what is and what is not a 'motor vehicle.' In general, vehicles that are equipped with tracks or are otherwise incapable of highway travel are not motor vehicles. Likewise, vehicles that are designed and sold solely for off-road use (e.g., airport runway vehicles and underground mining vehicles) are not motor vehicles even if operationally capable of highway travel. They would, however, be considered motor vehicles if the manufacturer knew that a substantial proportion of its customers actually would use them on the highway. Vehicles that use the public highways on a necessary and recurring basis are considered motor vehicles. Furthermore, even if the majority of a vehicle's use will be off-road but it will spend a substantial amount of time on-road, this agency has interpreted that to be a motor vehicle. We appreciate your interest in this matter and will provide the Under Secretary with a copy of this letter. Please contact us if we can be of further assistance. Sincerely, John Womack Acting Chief Counsel cc: Under Secretary, Kuwait Ministry of Commerce"; |
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ID: aiam4476OpenMr. Richard W. Ward Vice President K-D Lamp Company 1910 Elm Street Cincinnati, OH 45210; Mr. Richard W. Ward Vice President K-D Lamp Company 1910 Elm Street Cincinnati OH 45210; "Dear Mr. Ward: This is in reply to your letter of September 14, l988 asking for a clarification of Federal requirements for the minimum lens area for turn signal lamps and stop lamps. The understanding expressed in your letter is correct. The SAE materials for turn signal lamps and stop lamps for wide vehicles incorporated by reference in Table I apply to original equipment on vehicles currently being manufactured, and to equipment intended to replace such original equipment. These standards were expressly incorporated to supersede earlier versions of SAE standards for turn signal lamps and stop lamps. However, in recognition that original equipment lamps made to earlier SAE specifications might not be compatible with the electrical systems of vehicles designed to conform to later SAE specifications, the agency adopted paragraphs S4.l.l.6 and 4.l.l.7, allowing the continued manufacture for replacement purposes only, of turn signal lamps and stop lamps designed to conform to earlier specifications. Both sections incorporate in their text portions of the earlier SAE standards. Because the earlier specification for turn signal lamps, J588d, required an effective projected luminous area not less than 12 square inches for turn signal lamps on wide vehicles, this requirement is also specified in S4.1.1.7 for replacement lamps manufactured in conformance with J588d. In short, your interpretation is correct with respect to turn signal lamps manufactured for installation on vehicles whose overall width is 80 inches or more. Single compartment turn signal lamps designed to conform to SAE J588e need meet only a minimum luminous lens area of 8 square inches. But if a turn signal lamp is manufactured to replace a turn signal lamp that was designed to conform to SAE J588d, its minimum luminous lens area is 12 square inches. I hope this clarifies the matter for your customer. Sincerely, Erika Z. Jones Chief Counsel"; |
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ID: aiam2725OpenMr. James O. Peterson, Administrator, Division of Motor Vehicles, Department of Transportation, 4802 Sheboygan Avenue, Madison, WI 53707; Mr. James O. Peterson Administrator Division of Motor Vehicles Department of Transportation 4802 Sheboygan Avenue Madison WI 53707; Dear Mr. Peterson: This responds to your September 20, 1977, letter asserting that th Wisconsin requirement for minimum seat spacing does not conflict with the Federal requirement for maximum seat spacing found in Standard No. 222, *School Bus Passenger Seating and Crash Protection*.; Section 103(d) of the National Traffic and Motor Vehicle Safety Act o 1966 (the Act) (15 U.S.C. 1381 *et seq*.) specifies that no State shall have in effect a safety standard concerning an aspect of performance regulated by a Federal safety standard, unless the State standard is identical. The Act provides a limited exception to the above where a State or local municipality has a requirement which applies only to vehicles purchased for their own use and which imposes a higher standard of performance. Both Standard No. 222, which regulates maximum seat spacing, and the Wisconsin standard, which regulates minimum seat spacing, regulate the same aspect of performance. This position is supported by our statements in Notice 5 of Standard No. 222 (41 FR 4016) which expressed the opinion that seat spacing is the regulated aspect of performance (copy enclosed). Since your State standard is not identical to the Federal standard, it is the opinion of the NHTSA that it is preempted.; You should note that although you are not permitted to impose thi State standard on all vehicles used in your State, the Federal government does not preclude you from purchasing any buses for your own use from among the several designs now in production. You could, therefore, purchase only those vehicles that afford you the minimum knee space you desire. You should note further that purchase for your own use has been interpreted to mean purchased by a contractor under contract to provide transportation for school children.; Sincerely, Joan Claybrook |
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ID: aiam4112OpenMr. Marshall D. Carter, Whisper Electric Car AS, 87 Hadsundve, Als, DK-9560 Hadsund, Denmark; Mr. Marshall D. Carter Whisper Electric Car AS 87 Hadsundve Als DK-9560 Hadsund Denmark; Dear Mr. Carter: This is in reply to your letter of February 18, 1986, asking tw questions with respect to the Federal motor vehicle safety standards.; With respect to electric vehicles, you have asked 'is there a standar regulating the minimum length of time that the hazard light must be able to function at a minimum intensity, on the service battery alone?' There is no such standard. The vehicle must be equipped with a hazard warning signal operating unit designed to conform to SAE J910, January 1966, and a hazard warning signal flasher designed to conform to SAE J945, February 1966, but there is no requirement in the Federal motor vehicle safety standard on vehicle lighting, Standard No. 108, that the hazard warning signal flashers perform for a minimum specified period of time in service.; You have also asked 'Is there a requirement that the vehicle b equipped with an illuminated display, indicating gear selection?' We are unable to confirm your conclusion that there is no such requirement under Standard No. 101. Paragraph S3.2 of Standard No. 102 requires that identification of shift lever positions or patterns be permanently displayed in front of the driver. Paragraph S5.3.1 of Standard No. 101 requires illumination of the 'gauges' listed in Column 1 of Table 2 that are accompanied by the word 'Yes' in Column 5. The last 'gauge' listed is 'Automatic gear position', and the word 'Yes' appears in Column 5. The automatic gear position is a 'gauge' as defined by paragraph S4 of Standard No. 101, 'a display that is listed in ...Table 2 and is not a telltale'. Thus the Federal standards do require illumination of the gear positions of automatic transmissions, but not of manual ones.; I hope that this responds to your questions. Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam4987OpenMr. Michael Love Manager, Compliance Porsche Cars North America, Inc. P.O. Box 30911 Reno, Nevada 89520-3911; Mr. Michael Love Manager Compliance Porsche Cars North America Inc. P.O. Box 30911 Reno Nevada 89520-3911; Dear Mr. Love: This responds to your letter of April 3, 1992 requesting concurrence by this Office in your interpretation of the requirements of Standard No. 108 for the location of center highmounted stop lamps. Porsche wishes to install a center lamp on the movable spoiler of its 911 Carrera, a configuration previously approved by this Office providing that all photometric and visibility requirements are met. However, S5.3.1.8 of Standard No. 108 requires that 'If the lamp is mounted below the rear window, no portion of the lens shall be lower than 6 inches below the rear window on convertibles, or 3 inches on other passenger cars.' Although Porsche's intended center lamp meets this requirement with the spoiler in the extended position (when the car reaches 45 to 55 mph and slows to 9 to 12 mph), at other times, when the spoiler is lowered, the center lamp would be 7.5 inches below the window on the coupe, and 9.5 inches for the convertible. Nevertheless, you believe that this may be acceptable. You cite an opinion rendered Mazda in which NHTSA did not object to center lamps mounted on tailgates because, as we advised Mazda, the center lamp is a 'supplementary' lamp, and that 'Even if the deck, hatch, or tailgate upon which it is mounted should be open, following drivers may still observe the signals of the primary stop lamps. . .' You further quote NHTSA's frequently repeated advisory that 'Compliance of a vehicle is determined with respect to its normal driving position. . . ,' and argue that Porsche's design 'fulfills the spirit of the height requirements under all conditions' and the height requirement itself 'under a majority of 'normal driving conditions.'' You further argue that even in the down position the triangular relationship between the center lamp and the stop lamps is retained. Finally, you argue that the proposed lamp conforms with NHTSA's philosophy to make Standard No. 108 more performance-oriented 'by fulfilling the photometric requirements at all positions.' I am sorry that we cannot concur in your interpretation. When we judge whether a vehicle meets the location and visibility requirements of Standard No. 108, we determine compliance of the vehicle in what appears to us to be its normal operating or driving position. The fact that the vehicle may not comply under all conditions of operation is, of course, of concern to us, but we try to weigh the realities of vehicle design and usage against the need of the public for safety. In the Mazda interpretation, there was no question that the vehicle as manufactured would comply with the locational requirement for center lamps when the tailgate was closed. The 'normal driving position' of a vehicle with a tailgate is with the tailgate in the closed position, and use of a vehicle with the tailgate not closed is likely to be infrequent compared with its use with the tailgate closed. In another interpretation, rendered years ago, the fact that a vehicle with hydraulic suspension would not meet the minimum height requirements for headlamps with the vehicle at rest was considered a technical noncompliance only because by the time the vehicle was in its normal operating condition (with the engine running and the car ready to move into the stream of traffic), the suspension had raised the vehicle to a height where the headlamps exceeded the minimum height requirements. By contrast, the center lamp on the Carerra will not meet the locational requirements from a state of rest up to a minimum of 45 mph, that is to say, under low-speed urban driving conditions where the center lamp is most likely to achieve its purpose of reducing the frequency and severity of rear end impacts. This, to us, is the 'normal operating position' of the Carerra with respect to the location of the proposed center lamp. I would like to close by pointing out that the agency went to a considerable extent in considering the comments of manufacturers before adopting the requirements of S5.3.1.8, in order to minimize design restrictions consistent with safety. NHTSA proposed three alternative locations, and adopted one that was less restrictive than any of the alternatives. Subsequently, pursuant to petitions for reconsideration by vehicle manufacturers, NHTSA relaxed the location requirements of S5.3.1.8 even further. Sincerely, Paul Jackson Rice Chief Counsel; |
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ID: aiam3948OpenMr. M. Mizuguchi, Ashimori Industry Co., Ltd., 12, 4-chome Yokobori, Higashi-ku, Osaka, Japan; Mr. M. Mizuguchi Ashimori Industry Co. Ltd. 12 4-chome Yokobori Higashi-ku Osaka Japan; Dear Mr. Mizuguchi: Your letter of February 28, 1985, was forwarded to my office for reply You asked whether the webbing attached to a buckle you intend to use must meet the webbing width requirement of S4.2 of Standard No. 209, *Seat Belt Assemblies*. The webbing is enclosed in a plastic sheath. As explained below, the webbing must meet the width requirement of the standard.; S4.2 of Standard No. 209 provides that the 'width of the webbing in seat belt assembly shall be not less than 1.8 inches, except for portions that do not touch a 95th percentile adult male with the seat in any adjustment position and the seat back in the manufacturer's nominal design riding position when measured under the conditions prescribed in S5.1(a).' The purpose of S4.2 is to ensure that belt webbing which comes into contact with an occupant has a minimum width that spreads the load imposed by the belt in a crash. By requiring webbing to spread rather than concentrate the load, the belt width requirement helps minimize the possibility of webbing-caused injury.; In the case of your design, the webbing is enclosed in tightly-fitting plastic sheath. You state that the webbing/sheath combination can come into contact with an occupant. The sheath enclosed with your sample is made from an easily deformable plastic. Thus, when the crash loads are imposed by the belt, the sheath will deform and the crucial factor in concentrating the load on an occupant is the width of the belt. Since the webbing/sheath combination can contact and impose crash loads on an occupant, the agency concludes that the webbing must meet the minimum width requirement of S4.2.; If the webbing were encased in a reinforced sheath that did no appreciably deform under loading, the agency would consider both the width of the webbing and its encasing sheath in determining whether the requirement of S4.2 was met.; I have enclosed the sample of your product sent with your letter. I you have any further questions, please let me know.; Sincerely, Jeffrey R. Miller, Chief Counsel |
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ID: aiam4904OpenMr. Jt Covelli President Jt Covelli Marketing & Media 5501 Tolman Terrace Madison, WI 53711; Mr. Jt Covelli President Jt Covelli Marketing & Media 5501 Tolman Terrace Madison WI 53711; "Dear Mr. Covelli: This responds to your recent undated letter t Taylor Vinson of this Office with respect to whether Federal law allows the use of decals on center highmounted stop lamps. You report that Wisconsin has no law governing the use of a decal on the brake light. THe subject is a complicated one under Federal law, but I shall try to explain it as simply as possible. There is no restriction under Federal law on the application of a decal to the center stop lamp, if the decal is placed there by the vehicle owner. Center stop lamps were not required on passenger cars manufactured before September 1, l985, and there are no Federal restrictions upon application of decals to lamps on pre-l986 model cars that may have been retrofitted with them. With respect to application of the decal on the center lamp of a passenger car manufactured on or after September 1, l985, Federal law prohibits the application a decal by a manufacturer, distributor, dealer, or repair shop, either before or after its sale to the first owner, if the application of the decal creates a noncompliance with the Federal motor vehicle safety standard on lighting. Conversely, such application is permitted if the lamp remains in compliance with all applicable Federal requirements with the decal installed. For example, the Federal standard calls for a minimum 'effective projected luminous area' of 4 l/2 square inches. Application of a decal to a lamp meeting the minimum area requirement would reduce the effective projected luminous area below 4 1/2 square inches, creating a noncompliance. On the other hand, if that area were large enough, and more than 4 1/2 square inches of it remained after the application of a decal, application of the decal would not create a noncompliance with the luminous area specification. The standard also calls for measurement of photometric performance at certain specified test points on the lamp. Obviously, the lamp must continue to provide the minimum photometric performance specified by the standard for those test points with the decal applied. Thus, whether application of a decal by a manufacturer, distributor, dealer, or repair shop creates a noncompliance is dependent upon the size of the lamp and the size, lettering, and transparency of the decal. Sincerely, Paul Jackson Rice Chief Counsel"; |
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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.