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: aiam3871OpenMr. Donald W. Vierimaa, Director of Engineering, Truck Trailer Manufacturers Association, 1020 Princess Street, Alexandria, VA 22314; Mr. Donald W. Vierimaa Director of Engineering Truck Trailer Manufacturers Association 1020 Princess Street Alexandria VA 22314; Dear Mr. Vierimaa: This is in reply to your letter of December 7, 1984, asking ou 'concurrence that the front clearance lamps on a trailer with a low front end or one designed to be equipped with a tarpaulin...may be mounted at the trailer frame level (about 50 inches above the ground), to avoid these lamps reflecting into the driver's eyes by way of the side view mirror.'; You thoughtfully attached a copy of my letter to you of November 10 1981 in which I advised you that 'the determination of practicability is one that is made by the manufacturer of the trailer', and that 'NHTSA will accept a determination that mounting clearance lamps at the top...is not practicable if such lamps are reflected into the driver's eyes by way of the side view mirror.' That remains our view if the configuration of any trailer is such that location of clearance lamps at or near the top of the trailer results in the reflection of the light into the eyes of the driver of the truck tractor.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam2299OpenMr. Lawrence F. Henneberger, Arent, Fox, Kintner, Plotkin & Kahn, Federal Bar Building, 1815 H Street, N.W., Washington, D.C. 20006; Mr. Lawrence F. Henneberger Arent Fox Kintner Plotkin & Kahn Federal Bar Building 1815 H Street N.W. Washington D.C. 20006; Dear Mr. Henneberger: This is in response to your March 26, 1976, letter concerning th application of S108(a)(2)(A) of the National Traffic and Motor Vehicle Safety Act of 1966, as amended (the Act), to aftermarket installations of trailer hitches.; >>>Section 108(a)(2)(A) specifies that: No manufacturer, distributer, dealer, or motor vehicle repair busines shall knowingly render inoperative, in whole or part, any device or element of design installed on or in a motor vehicle or item of motor vehicle equipment in compliance with an applicable Federal motor vehicle safety standard...<<<; You have requested clarification of the following sentence appearing i our March 1, 1976, letter to General Motors Corporation:; >>>Therefore, aftermarket trailer hitches must also be installed i such a way that compliance with Standard No. 301-75 is preserved.<<<; A more precise characterization of the law on this subject is tha aftermarket trailer hitches must be installed in such a way that compliance with the standard is not *knowingly* compromised.; You are correct in your understanding that trailer hitch manufacturer are not required to certify that their products comply with Standard No. 301-75, *Fuel System Integrity*. Despite the effect of S108(a)(2)(A), this standard applies only to vehicles. There is no Federal motor vehicle safety standard that applies to trailer hitches. Further, there is no duty on the part of hitch manufacturers, distributors, dealers, or installers to certify that the installation of a trailer hitch on a used vehicle does not compromise the vehicle's compliance with Standard No. 301-75. Please note that the installation of a trailer hitch on a certified vehicle before the vehicle's first purchase in good faith for purposes other than resale is governed by S108(a)(1)(A) of the Act and the alterer provisions in 49 CFR Part 567, *Certification*.; Sincerely, Frank A. Berndt, Acting Chief Counsel |
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ID: aiam2333OpenMr. W. G. Milby, P.O. Box 937, Fort Valley GA 31030; Mr. W. G. Milby P.O. Box 937 Fort Valley GA 31030; Dear Mr. Milby This responds to Blue Bird Body Company's May 29, 1976, questio whether safety chains are prohibited across the opening of a side or rear emergency door that is provided in satisfaction of S5.2.3.1 of Standard No. 217, *Bus Window Retention and Release*. You note that the State of Washington plans to require a seat guard' at side emergency doors to prevent students from accidentally falling through these openings.; The requirements of Standard No. 217 for school buses manufactured o or after October 26, 1976, specify that each school bus shall be equipped with either a rear emergency door or a side emergency door and a rear window (S5.2.3.1). Unobstructed passage through these exits from the interior of the bus is required by S5.4. A parallelepiped of specified dimensions must be capable of unobstructed passage through rear doors, and the rearmost point of a seat back must coincide with the forward edge of a side emergency door, so that unobstructed passage from the vehicle interior is preserved.; The agency's intent in specifying these emergency exit provisions is t assure unimpeded egress from school buses in the event of accident. Small children are often transported in school buses, and provisions for emergency exits should be as simple as possible to assist their exit. For these reasons, sections S5.2.3.1 and S5.4 prohibit the installation of safety chains across any emergency exit provided in satisfaction of S5.2.3.1.; Section 103(d) of the National Traffic and Motor Vehicle Safety Ac provides:; S103 * * * * * >>>(d) Whenever a Federal motor vehicle safety standard under thi subchapter is in effect, no State or political subdivision of a State shall have any authority either to establish, or to continue in effect, with respect to any motor vehicle or item of motor vehicle equipment any safety standard applicable to the same aspect of performance of such vehicle or item of equipment which is not identical to the Federal standard. Nothing in this section shall be construed to prevent the Federal Government or the government of any State or political subdivision thereof from establishing a safety requirement applicable to motor vehicles or motor vehicle equipment procured for its own use if such requirement imposes a higher standard of performance than that required to comply with the otherwise applicable Federal standard.<<<; It is the opinion of this agency that the State of Washington' requirement would be preempted as of the effective date of the new school bus requirements of Standard No. 217, with regard to emergency doors that are installed in compliance with S5.2.3.1. The agency does not believe that the requirement for safety chains constitutes a higher level of protection, and has concluded that it would cause the vehicle to be in non-compliance with the requirements of S5.2.3.1 and S5.4.; Sincerely, Frank A. Berndt, Acting Chief Counsel |
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ID: aiam5419OpenHerr P. Binder ITT Automotive Europe GmbH Bietigheim-Bissingen Germany; Herr P. Binder ITT Automotive Europe GmbH Bietigheim-Bissingen Germany; "FAX 07142/73-2895 Dear Herr Binder: This responds to your FAX of Jul 19, 1994, requesting a reinterpretation of our letter to you of June 21, 1994. You had intended to ask us about taillamps rather than the turn signal lamps which were the subject of our letter. Your latest letter shows a rear motor vehicle lighting array of four lamps, two on the body and two on the tailgate. The lamps on the body contain turn signals, stop lamps, and taillamps. The lamps mounted on the tailgate contain backup lamps, rear fog lamps, and taillamps. Your letter asks for confirmation of your interpretation that: 'This lighting system is a multiple lamp arrangement, therefore the combination of taillamp 1 and taillamp 2 has to be used to meet the photometric requirements for 2 lighted sections (SAE J585e, 3.1 and Table 1).' This is correct. Paragraph 3.1 of SAE J585e states that 'multiple lamps may be used to meet the photometric requirements of a tail lamp.' Note 3 of Table 1 states that 'separately lighted sections . . . may be separate lamps', and that the photometric values are to apply when all sections that provide the tail signal are considered as a unit. 'Visibility will be judged with tailgate closed.' As we advised you in our earlier letter, this is also correct. 'Only taillamp 2 mounted on the tailgate will meet the requirements for an unobstructed projected illuminated area of 12.5 cm2 measured at 45 deg. inboard. This is in accordance with SAE J 585e, Par. 4.' Taillamp 1 and taillamp 2 together comprise the taillamp system. Thus it is not required that taillamp 1 meet the inboard visibility requirements when they are met by taillamp 2. You have also asked some general questions: 'Are there regulations which lamps has to be mounted on the body and which lamps are allowed on the tailgate?' No. Table IV's requirement for the location of rear stop, tail, and turn signal lamps is that they be 'as far apart as practicable.' However, Standard No. 108 does not specify which lamps must be mounted on the body and which are permissible on the tailgate. We encourage manufacturers to mount signal lamps on the body, such as is shown in your drawing. 'Is there a regulation to take an approval test in an authorized test laboratory (e.g. ETL)?' No. NHTSA has no authority to require a manufacturer to take approval tests or to designate test laboratories of which it approves. 'Which US-Authority has to be informed about this test?' A manufacturer is not required to inform NHTSA or any other governmental agency about its tests. However, NHTSA has the authority to ask a manufacturer to provide it with copies of test results, and generally does so if it finds failures to meet Standard No. 108 in its own tests. 'How long is this test valid?' 'After which period has this test to be repeated?' Under our laws, a lamp manufacturer is required to certify compliance of replacement equipment with Standard No. 108, and it is the manufacturer's determination when it should retest a lamp to verify that its certification of compliance remains correct. In our experience, manufacturers will retest when there are design changes to its products. Manufacturers also engage in surveillance testing of products after they have entered production to ensure that design tolerances continue to be met and that the lamp remains in compliance with the specifications of Standard No. 108. Sincerely, John Womack Acting Chief Counsel"; |
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ID: aiam2626OpenMr. H. K. Scheller, Project Engineer, AM General Corporation, 32500 Van Born Road, Wayne, MI 48184; Mr. H. K. Scheller Project Engineer AM General Corporation 32500 Van Born Road Wayne MI 48184; Dear Mr. Scheller: This is in reply to your letter of June 10, 1977, petitioning fo temporary exemption, on behalf of an electric truck, from Federal Motor Vehicle Safety Standards Nos. 102 and 301.; Your petition is inadequate for consideration at this time. manufacturer may apply for temporary exemption upon only one basis, while AM General's petition is an attempt to apply both on grounds of hardship (49 CFR 555.6(a)) and of low- emissions vehicle development (555.6(c)). On either basis the petition lacks the full complement of information required by Part 555.; In view of the fact that AM General has previously received a exemption (NHTSA Exemption No. 74-4) under 555.6(c) I suggest that you reapply on that basis, using the company's previous petition as a guide. Your present petition is inadequate under 555.6(c) because it does not provide 'reasons why the failure to meet the standard does not unreasonably degrade the safety of the vehicle' (555.6(c)(2)(iv)). It also does not supply the results of tests conducted on conforming vehicles to substantiate certification to Standards Nos. 102 and 301-75 (555.6(c)(2)(ii)), you have merely stated that AM General manufactures vehicles that meet these standards.; Under our general requirements for petitions, AM General must als provide its views why the granting of the petition would be in the public interest and consistent with the objectives of the National Traffic and Motor Vehicle Safety Act (555.5(b)(7)).; We shall be pleased to consider your petition further when you hav furnished the information requested.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam1909OpenMr. Roger Pelletier, Accounting Department, Traffic Div., P.H. Plastics, Inc., Parc Industriel, P.O. Box 220, Levis, Quebec, Canada G6V 6N8; Mr. Roger Pelletier Accounting Department Traffic Div. P.H. Plastics Inc. Parc Industriel P.O. Box 220 Levis Quebec Canada G6V 6N8; Dear Mr. Pelletier: This is in response to your letter of April 11, 1975, requestin information concerning the registration of certain vehicle types and laws relating to maximum length, width, and weight of vehicles.; It is unclear from your letter what you mean by 'registratio certificate.' The National Traffic and Motor Vehicle Safety Act (Pub. L. 89-563) requires that all vehicles used on United States highways be certified by their manufacturer as complying with all applicable Federal motor vehicle safety standards. 49 CFR Part 567 and 568 specify the manner in which this certification must be accomplished. If by 'registration certificate' you are referring to the necessary licensing of a vehicle for operation on United States roadways, I suggest you contact the States in which you would be operating your vehicles for the answers to your questions.; The questions you ask relating to 'special licenses' for 3-axle van and transportation of your own raw materials and products are also unclear. As I stated above, NHTSA regulations only require that you certify the compliance of your vehicles with all applicable motor vehicle safety standards. We do not limit the type of products that may be imported into this country.; With regard to your question concerning maximum limitations on traile and van length, width, and weight, this agency has no regulations which restrict the size of vehicles. As long as they meet the performance criteria established in our various safety standards, they have satisfied the provisions of the Traffic Safety Act. States generally have a limitation on the size of vehicles that operate on their roadways. Therefore, for this reason also, I suggest that you contact the States whose laws might affect the use of your vehicles within the United States.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam3934OpenMr. Hayley Alexander, Marketing Consultant, The LondonCoach Co., Inc., P.O. Box 1183, Mt. Clemens, MI 48043; Mr. Hayley Alexander Marketing Consultant The LondonCoach Co. Inc. P.O. Box 1183 Mt. Clemens MI 48043; Dear Mr. Alexander: This is in reply to your letter of March 25, 1985, asking for ou comments on your planned London Taxi marketing program.; Under the program, products of Carbodies Ltd. of Coventry, England would be imported 'devoid of an engine, transmission, and finished interior.' LondonCoach would then install 'an American engine, transmission and driveshaft, interior seats, coverings and details, and various exterior cosmetic trim items.' However, a 'representative' vehicle with the modifications mentioned above will have undergone all testing necessitated by the standards, at the Motor Industry Research Association in England. Vehicles would be certified by Carbodies as meeting the standards prior to importation, and LondonCoach Co., Inc., in the role of alterer, would attach the label attesting to continued compliance required by 49 CFR Section 567.7 upon completion of the modifications.; Under the National Traffic and Motor Vehicle Safety Act, certificatio of compliance of a motor vehicle can only be provided by the manufacturer or importer of a completed motor vehicle. Certification of compliance with at least four Federal motor vehicle safety standards is directly dependent upon the manner in which the Carbodies vehicles are completed by LondonCoach: Standard No. 124, *Accelerator Control Systems*, Standard No. 207, *Seating Systems*, Standard No. 301, *Fuel System Integrity*, and Standard No. 302, *Flammability of Interior Materials*. Therefore, LondonCoach is the only party who can certify compliance of the completed vehicle with Federal motor vehicle safety standards. As the manufacturer, LondonCoach is also responsible for assigning and affixing the vehicle identification number (VIN) to each vehicle, according to the requirements of Standard No. 115, *Vehicle Identification Number--Basic Requirements*, and 49 CFR Part 565, *Vehicle Identification Number--Content Requirements*.; The Carbodies products are an assemblage of items of motor vehicl equipment and should be labeled as equipment items for importation into the United States. Carbodies should certify that each item of motor vehicle equipment that is covered by a Federal motor vehicle safety standard complies with such standard. Those items are brake hoses, new pneumatic tires, brake fluid, surface glazing, seat belt assemblies, and lamps, reflective devices, and associated equipment. This certification should free LondonCoach, as the importer, from the obligation under 19 CFR 12.80 to post a compliance bond upon entry into the United States.; Sincerely, Jeffrey R. Miller, Chief Counsel |
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ID: aiam5049OpenMr. Tom Mario Vice President Sales Sealco Air Controls, Inc. 215 East Watkins Street Phoenix, AZ 85004; Mr. Tom Mario Vice President Sales Sealco Air Controls Inc. 215 East Watkins Street Phoenix AZ 85004; "Dear Mr. Mario: This letter responds to your follow-up inquiry about recent amendment to Federal Motor Vehicle Safety Standard No. 121, Air Brake Systems that deletes the requirement for a trailer to have a separate reservoir capable of releasing the parking brake. The final rule allows air from the tractor supply lines to be used to release the parking brakes instead of air from such a reservoir. (56 FR 50666, October 8, 1991, copy enclosed) In our earlier response to you dated May 21, 1992, we stated that a trailer could be equipped with a protected separate reservoir after the amendment became effective. That letter explained that while the amendment deleted a provision requiring a protected service reservoir, nothing in the amendment would prohibit a trailer from being equipped with this device. You now ask what pressure must be retained in the supply line with any single leakage type failure in the service brake system if an original equipment manufacturer decides to use a system with a protected reservoir. You explained that you are aware of a system that has a 60 p.s.i. pressure amplification valve that results in having 90 p.s.i. holding off the spring brakes. I am pleased to have this opportunity to further explain our requirements to you. In deleting the provision requiring a separate reservoir capable of releasing the parking brake, the agency adopted requirements in S5.8 addressing supply line pressure retention. That provision states that under certain test conditions 'any single leakage type failure in the service brake system (except for a failure of the supply line, a valve directly connected to the supply line or a component of a brake chamber housing) shall not result in the pressure in the supply line falling below 70 p.s.i., measured at the forward trailer supply coupling. . .' (S5.8.2) Based on the above provision, the pressure in the supply line is not permitted to fall below 70 p.s.i when measured at the forward trailer supply coupling. Accordingly, a system with 60 p.s.i. in the supply line measured at the forward trailer supply coupling would not comply with the express requirements set forth in S5.8.2. Please be aware that after October 8, 1992, the provision in S5.8.2 applies to all new trailers, including those manufactured with a protected separate reservoir. Your letter appears to imply that there would be no safety problem in having the pressure in the supply line falling to 60 p.s.i. if a pressure amplification valve served to hold off the spring brakes. I note, however, that problems could occur if only one trailer in a mixed train, multiple trailer combination used such an amplification valve. For example, if a single leakage-type failure in the service brake system of such a trailer resulted in the supply line pressure falling to 60 p.s.i., this could cause the supply line pressure in following trailers to also fall to 60 p.s.i. If the following trailers were not equipped with an amplification valve, they could experience brake drag. I hope this information is helpful. If you have any further questions about NHTSA's safety standards, please feel free to contact Marvin Shaw of my staff at this address or by telephone at (202) 366-2992. Sincerely, Paul Jackson Rice Chief Counsel Enclosure "; |
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ID: aiam2276OpenHonorable Delbert L. Latta, House of Representatives, Washington, DC 20515; Honorable Delbert L. Latta House of Representatives Washington DC 20515; Dear Mr. Latta: Thank you for your March 23, 1976, request for consideration of th views of a constituent that provision of air cushion restraint systems in passenger cars would be too costly, and that motor vehicle regulation should concentrate on used vehicles because they are equipped with fewer safety and emission features.; As you are aware, the National Traffic and Motor Vehicle Safety Ac (the Act) (15 U.S.C. S 1391 *et seq*.) directs the Secretary of Transportation to issue motor vehicle standards that will reduce the number of accidents and deaths, and the severity of injuries, that occur on our nation's highways. The National Highway Traffic Safety Administration (NHTSA) of the Department of Transportation evaluates the available means to meet this goal. Restraining vehicle occupants to protect them against impact with the vehicle interior in a crash offers one of the greatest opportunities for improving motor vehicle safety. Reliance on existing seatbelt systems has prevented only a small portion of the death and injuries that occur from impact with the vehicle interior. For this reason, other means of providing restraint are under consideration. I can assure you that the issues of purchase cost, replacement cost, and the alternatives to air cushions are being included in this consideration.; The safe operation of motor vehicles has traditionally been regulate by the individual States and not the Federal Government. While the Act does not authorize the retrofit of safety devices to vehicles in use, the NHTSA has issued a highway safety program standard for State periodic motor vehicle inspection programs (23 CFR S 1204.4). Part 570, *Vehicle in Use Standards* (49 CFR Part 570), sets forth a procedure for inspection of older vehicles for use by the States in implementing the program standard. Also, the NHTSA has established demonstration diagnostic inspection projects that include emission as well as safety inspection of vehicles in use.; I have no basis for comment on the reported decision by Allstat Insurance Company not to consider the effects of bumper modification in establishing its premium structure.; I trust that this response will answer your constituent's questions. Sincerely, William T. Coleman, Jr. |
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ID: aiam4208OpenMrs. Bettie Lou Simcox, 10 Martin Place, Little Falls, NJ 07424-1709; Mrs. Bettie Lou Simcox 10 Martin Place Little Falls NJ 07424-1709; Dear Mrs. Simcox: This is in reply to your letter of August 28, 1986, to Taylor Vinson o this Office regarding the acceptability of an aftermarket stop lamp intended for installation on motorcycles. The product is a stop lamp that, when the brake is applied, pulses before going into a steady- burning mode. The New Jersey Department of Motor Vehicles has informed you that stop lamps are required by Federal law to be steady-burning. A representative of this agency has told you that such a lamp would be acceptable as a supplementary stop lamp, but not as a replacement lamp. You are writing us for confirmation of the Federal requirement.; Your understanding is essentially correct. Federal Motor Vehicle Safet Standard No. 108 *Lamps, Reflective Devices, and Associated Equipment* requires most vehicle lamps, including stop lamps, to be steady- burning in use, though signal lamps such as turn signals and hazard warning signals must flash. Further, the replacement of an original equipment steady-burning stop lamp with one that flashes before becoming steady-burning would be considered a violation of the National Traffic and Motor Vehicle Safety Act if performed by a manufacturer, distributor, dealer, or motor vehicle repair business, though not if performed by the owner of the vehicle. As for the acceptability of the device as a supplementary stop lamp, Standard No. 108 really does not contemplate a supplementary stop lamp for motorcycles. Although requiring at least one stop lamp, the standard allows two provided that they 'are symmetrically disposed around the vertical centerline.' We interpret this as meaning that a second stop lamp must be identical in all respects to the first one, for surely a confusing situation would result if stop lamps on either side of the vertical centerline were unequal in size or in method of operation. However, the flashing/steady burning stop lamp mounted on the vertical centerline would be permissible as an addition to motorcycle stop lamp systems consisting of two lamps mounted on either side of the vertical centerline. Alternatively, if you wished to add two pulsing stoplamps mounted symmetrically around the vertical centerline in addition to the steady-burning original equipment stoplamp, that also would be permissible.; We appreciate your interest in motorcycle safety, and your taking th time to write us of your concerns.; Sincerely, Erika Z. Jones, 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.