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: aiam2280OpenMs. Constance Newman, Assistant Secretary for Consumer Affairs and Regulatory Functions, Department of Housing and Urban Development, 451 Seventh Street, S.W., Washington, D.C. 20410; Ms. Constance Newman Assistant Secretary for Consumer Affairs and Regulatory Functions Department of Housing and Urban Development 451 Seventh Street S.W. Washington D.C. 20410; Dear Ms. Newman: I am writing in response to questions that have been raised about th National Highway Traffic Safety Administration's (NHTSA) authority to regulate mobile homes. As you may know, mobil homes have been considered to be 'motor vehicles' as that term is defined in the National Traffic and Motor Vehicle Safety Act of 1966 (15 U.S.C. 1391 et seq.) ('the Vehicle Safety Act'). As such, they have been subject to Federal Motor Vehicle Safety Standard No. 108 (*Lamps, Reflective Devices, and Associated Equipment) and to our authority regarding the notification and remedy of noncompliances and defects related to motor vehicle safety.; The National Mobile Home Construction and Safety Standard Act of 197 (42 U.S.C. 5401 et seq.) ('the Mobile Home Act') established within the Department of Housing and Urban Development a comprehensive program for the regulation of mobil homes. We have concluded that one result of that statute's enactment was the implied repeal of the NHTSA's authority with respect to mobile homes. Accordingly, we consider that the enactment had the effect of amending the Vehicles Safety Act's definition of 'motor vehicle' to exclude 'mobile homes' as the latter term is defined in the Mobile Home Act. We are preparing a Federal Register notice that will reflect this conclusion.; Sincerely, James B. Gregory, Administrator |
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ID: aiam0707OpenMr. A. R. Williams, Sales Manager, Ronway Trans Craft Systems, 80 Ross Road, Ashtabula, OH 44004; Mr. A. R. Williams Sales Manager Ronway Trans Craft Systems 80 Ross Road Ashtabula OH 44004; Dear Mr. Williams: Mr. Toms has asked me to reply to your letter of May 12, 1972, in whic you ask for guidance in regard to the Federal Motor Vehicle Safety Standards (FMVSS) that would apply to equipment described in your brochure.; Your responsibilities under the National Traffic and Motor Vehicl Safety Act of 1966 (the Act) and FMVSS and regulations would depend on the way the equipment is marketed and you should be guided by the following:; >>>1. If you market the body and/or the chassis adaptor unit, the would be considered items of motor vehicle equipment for which there are no applicable standards. Although the standards do not apply, you should assure yourself that no safety-related defects exist.; 2. A person who mounts the chassis adaptor unit on a chassis-cab woul be considered the final stage manufacturer within the meaning of Part 568 of Title 49 of the Code of Federal Regulations and he would be responsible for conformity. The following pertinent publications are enclosed.; 1. The National Traffic and Motor Vehicle Safety Act of 1966. 2. Federal Motor Vehicle Safety Standard No. 108 with amendment effective on January 1, 1972.; 3. Notice of Publications Change. 4. Part 566 of Title 49 of the Code of Federal Regulations Manufacturer Identification.; 5. Part 567 - Certification 6. Part 568 - Vehicles Manufactured in Two or More Stages. 7. Part 573 - Defect Reports. 8. Part 574 -Tire Identification.<<< It is anticipated that many members of my staff will be attendin Transpo 72. They, no doubt, will be very interested in seeing your exhibit as well as the many others that will be there. However, I would recommend that you direct any questions you might have relating to interpretations of the standards and regulations to the Administration.; Thank you for your interest in the programs of the National Highwa Traffic Safety Administration.; Sincerely, Robert L. Carter, Associate Administrator, Motor Vehicl Programs; |
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ID: aiam4324OpenMr. Andrew G. Baird, II, Executive Director, North Platte Development Corporation, P. O. Box 968, North Platte, NE 69101; Mr. Andrew G. Baird II Executive Director North Platte Development Corporation P. O. Box 968 North Platte NE 69101; Dear Mr. Baird: This responds to your letter concerning a design for a remote automati starting system for motor vehicles. Enclosed is a copy of a September 15, 1986 letter, addressed to C&A Control System, Inc., which discusses the general issues raised by your letter. Also enclosed is a copy of an information sheet which we prepared for manufacturers of motor vehicles and motor vehicle equipment.; While remote automatic starting systems can be designed so that they d not conflict with any Federal motor vehicle safety standard, you should be aware that this agency strongly advises that cars should never be left unattended with the engine running. Remote automatic starting systems create that vehicle condition. I am enclosing a copy of a recent press release which cautions motorists that allowing a cold engine to idle for an extended period of time could lead to a fire. The agency has previously warned of the danger of inadvertent movement by unattended cars which are left running.; I urge you to consider these and other safety issues as you evaluat the safety of your device.; Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam1957OpenHonorable G. William Whitehurst, House of Representatives, Washington, DC 20515; Honorable G. William Whitehurst House of Representatives Washington DC 20515; Dear Mr. Whitehurst: A reply to your inquiry of June 5, 1975, concerning grade labellin regulations for new passenger car tires was transmitted to you on June 13 by Mr. James H. Cromwell of the Department of Transportation. Mr. Cromwell also referred your inquiry to me for additional comments.; As you are undoubtedly aware, the original impetus for th establishment of a uniform quality grading system for motor vehicle tires was provided by the National Traffic and Motor Vehicle Safety Act of 1966, which established this agency. The Congress, cognizant of the problems which beset the consumer when he attempts to make an informed choice of motor vehicle tires based on the relative merits of tire brands, included a specific Section 203 in the aforementioned Safety Act of 1966 which states that, 'In order to assist the consumer to make an informed choice in the purchase of motor vehicle tires . . .the Secretary shall . . . prescribe by order, and publish in the 'Federal Register*, a uniform quality grading system for motor vehicle tires.'; The benefits of such a system, while difficult to quantify, represen an enormous potential since some 200,000,000 motor vehicle tires are produced per year and are presently sold to consumers without adequate quantitative measures of their performance. It is expected that, by facilitating increased and more meaningful competition, the quality grading information will enable the tire consumer to obtain more value per dollar than he has in the past. The rule will enable the consumer to judge relative tire performance from a simple grading system, and thereby select a tire which provides him with the optimum solution to his driving needs.; For your review and information, I am enclosing a copy of the Unifor Tire Quality Grading Standards (UTQGS) which was issued in the *Federal Register* dated May 28, 1975. The rule provides quantitative grading measures for three important tire properties -- i.e., treadwear, traction, and temperature resistance.; I trust the above information satisfies your needs. Should you have an further questions, I shall be glad to attempt to provide answers.; Sincerely, Robert L. Carter, Associate Administrator, Motor Vehicl Programs; |
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ID: aiam1958OpenHonorable G. William Whitehurst, House of Representatives, Washington, DC 20515; Honorable G. William Whitehurst House of Representatives Washington DC 20515; Dear Mr. Whitehurst: A reply to your inquiry of June 5, 1975, concerning grade labellin regulations for new passenger car tires was transmitted to you on June 13 by Mr. James H. Cromwell of the Department of Transportation. Mr. Cromwell also referred your inquiry to me for additional comments.; As you are undoubtedly aware, the original impetus for th establishment of a uniform quality grading system for motor vehicle tires was provided by the National Traffic and Motor Vehicle Safety Act of 1966, which established this agency. The Congress, cognizant of the problems which beset the consumer when he attempts to make an informed choice of motor vehicle tires based on the relative merits of tire brands, included a specific Section 203 in the aforementioned Safety Act of 1966 which states that, 'In order to assist the consumer to make an informed choice in the purchase of motor vehicle tires . . .the Secretary shall . . . prescribe by order, and publish in the 'Federal Register*, a uniform quality grading system for motor vehicle tires.'; The benefits of such a system, while difficult to quantify, represen an enormous potential since some 200,000,000 motor vehicle tires are produced per year and are presently sold to consumers without adequate quantitative measures of their performance. It is expected that, by facilitating increased and more meaningful competition, the quality grading information will enable the tire consumer to obtain more value per dollar than he has in the past. The rule will enable the consumer to judge relative tire performance from a simple grading system, and thereby select a tire which provides him with the optimum solution to his driving needs.; For your review and information, I am enclosing a copy of the Unifor Tire Quality Grading Standards (UTQGS) which was issued in the *Federal Register* dated May 28, 1975. The rule provides quantitative grading measures for three important tire properties -- i.e., treadwear, traction, and temperature resistance.; I trust the above information satisfies your needs. Should you have an further questions, I shall be glad to attempt to provide answers.; Sincerely, Robert L. Carter, Associate Administrator, Motor Vehicl Programs; |
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ID: aiam3512OpenMr. Joseph Granatelli, President, Grancor, Inc., 929 Olympic Boulevard, Santa Monica, CA 90404; Mr. Joseph Granatelli President Grancor Inc. 929 Olympic Boulevard Santa Monica CA 90404; Dear Mr. Granatelli: This is in reply to your letter of November 17, 1981, with respect t 'a non-substantive disagreement' of your Safety Alert Device 'with a strict interpretation of (FMVSS No. 108)'. Your system is wired into and operated through a vehicle's back-up lamp system which you have modified by adding 'a yellow sleeve over half of the back-up light bulb'. You state that the light cast is 'essentially the same as the white light. You further say that any deviation from Standard No. 108's requirement that back-up lamps emit white light is 'nonsubstantive'.; I assume that your letter to me is in response to the one that Georg Parker, Chief, Crash Avoidance Division, sent you on September 2, 1981. In that letter he explained that S4.1.3 prohibits the addition of equipment 'that impairs the effectiveness of lighting equipment' required by Standard No. 108, and stated that any activation of your system while the back-up lamps are in operation would be covered by this prohibition. As for color, you were informed that S4.1.3 imposed an absolute prohibition if the color of the light emitted by the deceleration warning system were green or white.; We cannot concur that the deviation from Standard No. 108 i 'non-substantive'. Standard No. 108 requires back-up lamps to be installed in motor vehicles and to emit a white light. We view S4.1.3 as precluding any device that would operate lighting equipment required by Standard No. 108 for a purpose other than that for which it is originally installed. Further, even if your system did not operate through the back-up lamp system but through separate and additional lamps, we would view use of a color other than red or amber as an impairment of the equipment originally installed to indicate the deceleration through braking of the vehicle (*i.e.*,, stop lamps).; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam0828OpenMr. J. W. Kennebeck, Manager, Safety & Development, Volkswagen of America, Inc., Englewood Cliffs, NJ, 07632; Mr. J. W. Kennebeck Manager Safety & Development Volkswagen of America Inc. Englewood Cliffs NJ 07632; Dear Mr. Kennebeck: This is in reply to your letter of July 27, 1972, requesting a interpretation of S4.3 of Motor Vehicle Safety Standard No. 302, 'Flammability of Interior Materials', and an opinion regarding the applicability of Standard No. 302 to your Model 15 convertible top cover.; You ask whether the basic burn rate of not more than 4 inches pe minute or the burn rate of 2 inches in less than 60 seconds should be applied to material which self-extinguishes after 55 seconds at a burn distance of 3 inches. The answer to this question is that the basic burn rate of not more than 4 inches per minute applies to this case. The basic burn rate requirement, calculated according to the formula given in S5.3(g), applies whenever the tested material burns more than 2 inches or more than 60 seconds. This 2-inch, 60-second burn rate provided in the second sentence of paragraph S4.3 is given to simplify the calculation of certain self-extinguishing materials, not for the purpose of imposing an additional requirement.; In regard to your graphic illustrations and you request for our opinio with respect to the validity of your Figure 3, you are correct in assuming that materials falling under the B-line are acceptable and that the portions of the shaded area under the B-line in Figure 2 represent an overlap that is in the acceptable area. The second burn rate was intended as a means for rapid qualification of test specimens that, because of their specified flammability limits, would be acceptable without further calculation to determine the burn rate. Any materials falling outside of the 2-inch or 60-second limits require calculation. It would, as you suggest, be a further simplification to say that material that self-extinguishes before burning 2 inches meets the performance requirement and is acceptable.; You ask further whether Standard No. 302 applies to your Model 1 convertible top cover. We consider for this purpose a convertible top cover, or boot, to be part of the convertible top itself and consequently subject to the standard.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam4519OpenMr. M. Arisaka Manager, Automotive Lighting Homologation Sect. Stanley Electric Co., Ltd. 2-9-13, Nakameguro, Meguro-ku Tokyo 153 JAPAN; Mr. M. Arisaka Manager Automotive Lighting Homologation 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 May 31, 1988 asking about the acceptability of installing an additional red reflex reflector on the rear of a passenger car. The reflector would be centered between the two red reflex reflectors required by the standard. In your opinion, the additional reflector will not impair the effectiveness of other lighting equipment required by Standard No. 108. As you have properly noted, supplementary motor vehicle equipment including reflectors is permissible under paragraph S4.1.3 of Standard No. 108 as long as it does not impair the effectiveness of equipment that the standard requires. The determination of whether supplementary equipment, in fact, impairs the effectiveness of the required equipment is initially that of the manufacturer of the vehicle upon which the supplementary equipment is to be installed, and who certifies compliance with all applicable Federal motor vehicle safety standards including paragraph S4.l.3 of Standard No. 108. The National Highway Traffic Safety Administration neither approves nor disapproves of specific vehicle designs, and unless there are reasons to believe that the supplementary equipment will, in fact, impair the effectiveness of the required lighting equipment this agency accepts the manufacturer's determination. The drawing you attached shows the location of the two required rear reflex reflectors, and the supplementary one, but does not depict the location or types of other required rear lighting equipment, i.e. stop lamps, center highmounted stop lamp, taillamps, turn signal lamps, license plate lamp, and backup lamps. However, in your opinion the reflector will not impair the effectiveness of these lamps and the required reflectors, and the agency has no reason to believe that the third reflector will, in fact, impair the effectiveness of them. I hope this answers your question, and that the guidelines given in this letter will encourage you to reach satisfactory determinations without the necessity of submitting them to this agency for comment. We appreciate your continuing interest in motor vehicle safety. Sincerely, Erika Z. Jones Chief Counsel; |
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ID: aiam2559OpenMr. Stuart A. Mossman, President, Onics Holding, Inc., 1315 Commerce Center, 129 West Trade Street, Charlotte, North Carolina 28230; Mr. Stuart A. Mossman President Onics Holding Inc. 1315 Commerce Center 129 West Trade Street Charlotte North Carolina 28230; Dear Mr. Mossman: This responds to your March 29, 1977, letter asking whether severa vehicles that you describe would be considered 'vehicles other than passenger cars' for purposes of Standard No. 120, *Tire Selection and Rims for Motor Vehicles Other Than Passenger Cars*.; Vehicles other than passenger cars includes: multipurpose passenge vehicles, trucks, buses, motorcycles, and trailers, all of which are defined in the Code of Federal Regulations, Title 49, Part 571.3. Since the vehicles you describe appear to fall within the definition of multipurpose passenger vehicle or truck, they are considered 'vehicles other than passenger cars.' Accordingly, they must comply with the rim marking requirements of Standard No. 120.; Sincerely, Frank A. Berndt, Acting Chief Counsel |
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ID: aiam2765OpenMr. Garry Williams, Body Designer, Telsta Group, General Cable Corporation, P.O. Box 666, Westminster, CO 80030; Mr. Garry Williams Body Designer Telsta Group General Cable Corporation P.O. Box 666 Westminster CO 80030; Dear Mr. Williams: This is in reply to your letter of February 3, 1978, concernin placement of the rear identification lamps on a truck. Because the truck has a mast assembly located on the longitudinal axis of the vehicle and center of the rear axle, you have asked whether the lamps should be mounted 'on the mast as high as possible or on the rear face of the rear floor decking.'; Table II of Federal Motor Vehicle Safety Standard No. 108 requires rea identification lamps to be mounted 'as close as practicable to the top of the vehicle....' If placement on the mast interferes with the operation of the lift, or if the lamp would be easily damaged in that location, that location would not appear to be 'practicable' within the meaning of Standard No. 108, and the deck location would fulfill the practicability requirements.; You have also asked which is more important in locating identificatio lamps: '(1) ...as high as possible on a stationary surface and face the lights toward the rear, or (2) to locate to the most rearward surface and then as high as possible on that surface'. Your first choice is the correct one. The purpose of the three lamp cluster is to identify large and frequently slow moving vehicles under conditions of reduced visibility. Therefore, it is more important for the lamps to be located high than it is for them to be at the rear end of the vehicle, for example, on the cab rather than at the deck end. However, the decision as to what is 'practicable' is initially that of the manufacturer and we have generally found those decisions to be correct.; Sincerely, Joseph J. Levin, Jr., 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.