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: aiam4303OpenProf. P. Soardo, Istituto Elettrotecnico Nazionale, Galileo Ferraris, Strada delle Cacce, 91, 10135 Torino Italy; Prof. P. Soardo Istituto Elettrotecnico Nazionale Galileo Ferraris Strada delle Cacce 91 10135 Torino Italy; Dear Prof. Soardo: This is in reply to your letter of January 16, 1987, to the agency wit reference to the 'homologation in the U.S.A. of a headlamp - optically combined - capable of performing the function of auxiliary driving lamp or as an alternative to the function of the front fog lamp.' You have told us that the device is intended principally for the aftermarket and will use a two- filament H4 bulb, the main filament providing the 'driving beam,' and the secondary filament performing 'the 'fog' function.' When it is mounted on the vehicle it will 'meet the specific aiming requirements contained in the relevant SAE standard, for both light beams.'; As you may know, there are two types of laws in the United States tha pertain to motor vehicle lighting equipment, the laws of the United States government ('Federal' law), and those of the 50 individual States ('Local' law). One of these laws is Federal Motor Vehicle Safety Standard No. 108 *Lamps, Reflective Devices, and Associated Equipment.* Standard No. 108 specifies requirements for original equipment, and, as a general rule, only aftermarket equipment that is intended to replace original equipment. There are no original equipment requirements in Standard No. 108 for a combination driving-fog lamp such as you discuss, and hence there are no Federal aftermarket requirements for it either. Provided that this lamp does not impair the effectiveness of required front lamps, Standard No. 108 allows a vehicle manufacturer to install the driving-fog lamp as original equipment. Because Standard No. 108 does not allow use of the H4 bulb in headlamps for four-wheeled vehicles, it could not serve as a headlamp. There are no Federal restrictions preventing the sale of this device in the aftermarket as a supplementary lamp.; However, the lamp would be subject to local law, and some of the State may require approval of it before it is offered for sale. The approval of one State does not signify approval by another, so there would not be 'homologation' permitting sale in all States based upon approval by only one State. Even if a Local law does not require approval of a driving-fog lamp, it may forbid its use. We are unable to advise you on Local laws but you may wish to write the American Association of Motor Vehicle Administrator for an opinion. The address of this organization is 1201 Connecticut Avenue, N.W., Washington, D.C. 20036.; Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam1101OpenLouis A. Sisler, Esq., General Counsel, ADC Marketing, Inc., 4410 Executive West, Fort Wayne, IN 46808; Louis A. Sisler Esq. General Counsel ADC Marketing Inc. 4410 Executive West Fort Wayne IN 46808; Dear Mr. Sisler: This is in reply to your letter of March 29, 1973, to Mr. Schneide asking for a clarification that the Front Brake Light Adapter you describe 'does not fall within the provisions of Motor Vehicle Safety Standard No. 108.' The adapter, as we understand it, connects the stop lamps with the front turn signal lamps so that when the brakes are applied, the front turn signal lamps are activated in a steady-burning state, indicating that the vehicle is decelerating or has come to a halt.; In our opinion, use of the adapter as original equipment on a vehicl might be precluded by paragraph S4.1.3 of Standard No. 108 prohibiting devices that impair the effectiveness of the equipment required by the standard. The front turn signal lamp is a lamp that flashes in operation to indicate to oncoming drivers, or pedestrians, that the vehicle is preparing to turn, or that a potential hazard exists ahead (when the system is activated as a hazard warning system). Accordingly, when the brake pedal is applied, if the adapter overrides the flashing effect of the front signal lamps it would impair their effectiveness, and be prohibited by Standard No. 108.; The adapter would be permissible as original equipment, however provided that the signals still flash when the brakes are applied, but a State would not be preempted from regulating it. Nothing in the standard precludes aftermarket sale of the adapter, but its use also would be subject to regulation by the individual States.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam5142OpenMr. Milford R. Bennett Acting Director Automotive Safety Engineering GM Environmental and Energy Staff Box 9055 Warren, MI 48090-9055; Mr. Milford R. Bennett Acting Director Automotive Safety Engineering GM Environmental and Energy Staff Box 9055 Warren MI 48090-9055; "Dear Mr. Bennett: We have received the petition by General Motors (GM for temporary exemption of a fleet of approximately 50 GM electric vehicles (GMEVs) from several Federal motor vehicle safety standards. GM would retain title to and ownership of the GMEVs which would be provided to private individuals and used for demonstration purposes over a 2-year period. The exemptions would be effective October 1, 1993. For the reasons set forth below, we are unable to consider the petition in its present form, and recommend that you either supplement it or withdraw and resubmit it when it has been revised in accordance with our procedures. First, we have comments on several of the Safety Standards from which GM has requested exemption. With respect to Standard No. 105, GM appears to have requested exemption from the standard in its entirety, commenting that until 'resolution of remaining EV regulatory issues associated with FMVSS 105 . . . GM is unable to certify the GMEV . . . as being fully compliant . . . .' We suggest that GM restrict its request for exemption to the specific sections of Standard No. 105 that may be affected by the pending resolution of issues involving brakes for electric vehicles and that this will facilitate GM's argument that an exemption would not unduly degrade the safety of the GMEV. We also prefer the use of objective data to subjective terms where practicable. GM has requested exemption from some of the photometric requirements of Standard No. 108 because the possibility exists that candlepower values may be 'slightly below' the minimum requirements 'at a few test points'. Is it possible to identify the test points and to quantify the potentially lower candela at those points? Similarly, GM has argued that 'preliminary testing has indicated that' the GMEV will 'substantially comply' with Standards Nos. 208, 212 and 219. Under section 555.6(c)(2), a petitioner shall provide '. . . testing documentation establishing that a temporary exemption will not unreasonably degrade the safety of the vehicle . . . .' Therefore we ask GM to submit the preliminary test reports in substantiation of its petition. Finally, GM has also failed to set forth the arguments required by 49 CFR 555.5(b)(7) as to why an exemption would be in the public interest and consistent with the objectives of the National Traffic and Motor Vehicle Safety Act. We note in passing the unusual use in the petition of the argument that 'the GMEV will provide an overall level of safety that is substantially equivalent to the level of safety of nonexempted vehicles.' The argument of overall safety equivalence is the basis for exemption provided by Section 555.6(d), not Section 555.6(c) where a petitioner must demonstrate that an exemption would not unreasonably degrade the safety of the vehicle. However, we interpret GM's argument to mean that it views its failures to meet Standards Nos. 201, 208, 212, and 219, as technical in nature with essentially no degradation in safety, let alone a degradation that approaches unreasonableness. For this reason, we believe all the more strongly that GM should provide the preliminary test report results mentioned above. When we have received GM's new petition, we shall prepare a Federal Register notice requesting public comment. If you have any questions, you may refer them to Taylor Vinson of this Office (202-366-5263). Sincerely, John Womack Acting Chief Counsel"; |
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ID: aiam2687OpenMs. Martha Storts Amster, 5301 East Osborn Road, Phoenix, AZ 85018; Ms. Martha Storts Amster 5301 East Osborn Road Phoenix AZ 85018; Dear Ms. Amster: This responds to your June 20, 1977, letter concerning Federal schoo bus safety standards. Your letter was forwarded to us by Ms. Margaret Costanza, Assistant to the President, since these standards are promulgated by the National Highway Traffic Safety Administration (NHTSA).; As you may know, several new school bus safety standards are applicabl to school buses built after April 1, 1977. These standards were established in accordance with a directive from Congress in the Motor Vehicle and School Bus Safety Amendments of 1974 (Pub. L. 93-492). Congress enacted that directive after determining that school buses deserved additional safety protection to prevent deaths and reduce injuries.; In your letter, you contend that our standard pertaining to school bu seating (Standard No. 222) requires seat spacing that is too small for older school children. It is our understanding after extensive consultations with bus manufacturers that the new school bus seat spacing requirements result in seat spacing that is essentially equivalent to seat spacing in buses manufactured prior to April 1. Therefore, most new school buses should be manufactured similar to older buses as far as seat spacing is concerned. Some school buses, however, may have slightly reduced seat spacing. We are aware of concerns expressed about reduced seat spacing in some new buses. We are not convinced that the problem originates from the requirements of Standard No. 222, however. Currently, we are examining buses manufactured in accordance with the requirements of the standard to determine whether a modification of the standard is necessary.; Maximum seat spacing has been controlled in buses to provide for th passive restraint of school bus occupants. The seat backs in the new buses are designed to absorb the force of children colliding with them during a crash. If seat spacing were increased, the seats in these buses would not be capable of absorbing sufficient impact force to protect children in accidents. The NHTSA adopted the passive restraint approach to school bus safety in response to public comments claiming that to require only seat belts in school buses would not be sufficient since the belts might not be used by many children. Accordingly, to provide a significant increase in occupant protection, the agency adopted the passive restraint approach to school bus seat safety.; In a final question in your letter, you ask about the costs an benefits of the new school bus safety standards' requirements. The agency has estimated that the total industry cost of compliance with those standards is approximately $40 million annually. The benefits should include a reduction in the number of deaths and injuries resulting from school bus accidents.; If I can be of further assistance to you, do not hesitate to contac me.; Sincerely, Joan Claybrook |
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ID: aiam3995OpenMr. Leo Kagan, Director of Marketing, Automotive Division, Amco Manufacturing Corporation, 7425 Fulton Avenue, North Hollywood, CA 91605; Mr. Leo Kagan Director of Marketing Automotive Division Amco Manufacturing Corporation 7425 Fulton Avenue North Hollywood CA 91605; Dear Mr. Kagan: This is in reply to your letter of July 19, 1985, asking if deck-mounted rack loaded with luggage would cause a violation of the center high-mounted stop lamp provisions of Motor Vehicle Safety Standard No. 108.; The answer is no. Compliance with Standard No. 108 is determine independent of whether the luggage rack is loaded. However, if the rack is installed before sale of the vehicle to its first purchaser, or if it is installed after sale by a person other than the vehicle owner, care must be taken to insure that the photometric and visibility requirements for center high-mounted stop lamps continue to be met with the unloaded rack in place.; The lamp is intended to reduce the incidence of rear end collisions Loading the rack in a manner that obscures the light will reduce the safety benefits that the lamp provides both the driver of the car, and of any vehicle that follows, and is a practice that should be discouraged.; If you have any further questions, we shall be happy to answer them. Sincerely, Jeffrey R. Miller, Chief Counsel |
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ID: aiam0340OpenAndrew R. Hricko, Esq., General Counsel, Insurance Institute for Highway Safety, Watergate Six Hundred, Washington, DC 20037; Andrew R. Hricko Esq. General Counsel Insurance Institute for Highway Safety Watergate Six Hundred Washington DC 20037; Dear Mr. Hricko: This is in reply to your letter of April 30, 1971, requesting a interpretation of the terms 'cooling system' and 'fuel system' as used in Motor Vehicle Safety Standard No. 215.; You first ask whether 'cooling system' includes the various component of the vehicle's air conditioning system. The term is not intended to include the air conditioning system.; Your second question is whether 'fuel systems' would include pollutio control vapor cannisters (sic) and other components used to reduce fuel emissions. If such components contain fuel or fuel vapor they are considered to be a part of the fuel system.; Please advise us if further clarification is needed. Sincerely, Lawrence R. Schneider, Acting Chief Counsel |
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ID: aiam5512OpenMr. Marshall S. Reagle Sate-Lite Mfg. Co. 6230 Gross Point Road Niles, IL 60714; Mr. Marshall S. Reagle Sate-Lite Mfg. Co. 6230 Gross Point Road Niles IL 60714; "Dear Mr. Reagle: This is in reply to your recent FAX to Pat Boyd o this agency asking for a confirmation of an interpretation of certain reflex reflector requirements of Motor Vehicle Safety Standard No. 108, specifically S5.7.2.1(b) and (c). For your future reference, requests for interpretation should be addressed to the Chief Counsel. You state that Mr. Boyd informed you that 'any retro-reflector would have to be made in intervals of 4 inches' with the 0 degree at the two-inch mark, and that the reflective reading would have to comply with S5.7.2.1(b) or (c). He also informed you that, regardless of whether the segment was 4, 8, or 12 inches in length, the agency will test in 4-inch segments. This is correct. According to paragraph S5.7.2.2(a) and (b) of Standard No. 108, each reflector shall be installed 'with the center of each reflector not more than 100 mm from the center of each adjacent reflector.' As 100 mm is approximately 4 inches, this effectively limits the size of a reflector to a maximum length of 4 inches. However, this does not prohibit the mounting of two or three adjacent reflectors in 'segments' of 8 or 12 inches, whether separately or in a housing. As Mr. Boyd informed you, each discrete 4-inch segment must comply with paragraph S5.7.2.1(b) or (c). Paragraphs S5.7.2.1(b) and (c) specify reflectivity values for red and white reflex reflectors respectively 'at any light entrance angle between 30 degrees left and 30 degrees right, including an entrance angle of 0 degrees,' as well as 'any light entrance angle between 45 degrees left and 45 degrees right.' Your drawing of a 4-inch reflector correctly depicts the 0 degree light entrance angle at the 2-inch mark, in the center of the reflector. However, SAE Standard J594f, Reflex Reflectors, January 1977, incorporated by reference in Standard No. 108, requires the measurement of the other light entrance angles also with respect to the center of the reflector, rather than with respect to the ends as pictured in your drawing. If you have any further questions, you may call Taylor Vinson of this Office (202-366-5263). Sincerely, Philip R. Recht Chief Counsel"; |
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ID: aiam0710OpenMr. Edwin P. Palumbo, Executive Director, Rhode Island Consumers' Council, 365 Broadway, Providence, Rhode Island 02909; Mr. Edwin P. Palumbo Executive Director Rhode Island Consumers' Council 365 Broadway Providence Rhode Island 02909; Dear Mr. Palumbo: We have received your letter of March 15, 1972, which was forwarded t us by the Federal Trade Commission, concerning problems experienced by Mr. Ronald Dandeneau regarding a repossessed vehicle he purchased which was equipped with tires marked 'NA.' Mr Dandeneau claims he was told by a tire dealer that such tires are considered unserviceable, cannot be repaired, and are unsafe.; The sale of these tires by the tire manufacturer (we understand tha the practice is not limited to Uniroyal) is not prohibited by the National Traffic and Motor Vehicle Safety Act, and the Federal standard applicable to passenger car tires. The Federal standard applies only to tires before their first sale to a consumer, and does not apply to used tires such as these.; We understand that tires marked 'NA' are tires that have been adjuste previously, but for reasons that are not considered to affect the safety of the tire. Examples of such reasons are a lack of roundness and uniformity. While these conditions may produce riding qualities which some people find unsatisfactory, we presently have no evidence that such tires cannot be repaired or that they are unsafe.; Yours truly,Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam1802OpenMr. Fred W. Cords, Minnesota Automotive, Inc., Box 2074, North Mankato, MN 56001; Mr. Fred W. Cords Minnesota Automotive Inc. Box 2074 North Mankato MN 56001; Dear Mr. Cords: This is in reply to your letter of January 6, 1975, requesting a opinion on whether a person who installs a Mico Brake Lock device on a new vehicle before its sale to the first purchaser is required to affix an alterer label in accordance with 49 CFR SS 567.7 and 568.8. You state that you believe the device, which serves as a hydraulic parking brake, is readily attachable because it can be installed in a minimum amount of time and does not in any way alter the operation of the vehicle's original brake system.; The NHTSA will generally abide by a good faith determination on th part of a manufacturer that a device is readily attachable. Such a decision should be based primarily on the intricacy of the installation of the device. Simple tools, a relatively short installation time, and the ability to install the device without extensively modifying the vehicle would all be factors pointing to a decision that a component is readily attachable. You should note that section 567.7 of the Certification regulations also requires an alterer label when the installation of a component invalidates a vehicle's existing weight ratings, whether or not the component is readily attachable. On the basis of your letter, however, it appears to us that this would not occur as a result of installation of the Mico Brake Lock device.; If your device meets these criteria, no additional labeling will b required.; Yours truly, James C. Schultz, Acting Chief Counsel |
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ID: aiam2042OpenMr. Kenneth J. Mason, 1314 Spruce Street, Wausau, WI 54401; Mr. Kenneth J. Mason 1314 Spruce Street Wausau WI 54401; Dear Mr. Mason: We have received your letter of August 7, 1975, concerning the Unifor Tire Quality Grading Standards established by this agency. Although the formal comment period for the proposals on which this regulation is based ended April 23, 1975, we appreciate your support for the regulation as issued. A copy of your letter has been placed in our public files.; Thank you for expressing your interest. Sincerely, Frank A. Berndt, Acting 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.