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: aiam0457OpenMr. J. G. Abbott, Transportation Chemicals, Development & Service, Dow Chemical Europe, S.A., Todi-Strasse 68, 8810 Horgen 2, Switzerland; Mr. J. G. Abbott Transportation Chemicals Development & Service Dow Chemical Europe S.A. Todi-Strasse 68 8810 Horgen 2 Switzerland; Dear Mr. Abbott: This is in reply to your letter of September 24 to Francis Armstron regarding the effective date of the new Federal motor vehicle brake fluid standard, No. 116.; The effective date of March 1, 1972, means that any vehicl *manufactured* on or after that date for sale in the United States must be equipped with brake fluid meeting Motor Vehicle Safety Standard No. 116.; Sincerely, Lawrence R. Schneider, Chief Counsel |
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ID: aiam4947OpenGordon W. Didier, Esquire Butzel Long Suite 200 32270 Telegraph Birmingham, Michigan 48010-4996; Gordon W. Didier Esquire Butzel Long Suite 200 32270 Telegraph Birmingham Michigan 48010-4996; "Dear Mr. Didier: This responds to your request for an interpretatio of Federal Motor Vehicle Safety Standard No. 118 Power Windows (49 CFR 571.118), on behalf of your client, a manufacturer of automobile sunroofs. As you noted in your letter, the agency has published a final rule amending Standard No. 118 in the April 16, 1991 edition of the Federal Register (56 FR 15290). You requested clarification of certain requirements in that final rule. The agency has received several petitions for reconsideration of the final rule amending Standard No. 118. The agency is currently reviewing the merits of each petition. The agency will issue a notice in the Federal Register granting and/or denying the petitions. In that notice, the agency will also address the concerns raised in your request for an interpretation on Standard No. 118. Please let us know if you have any questions about the issues raised in your letter after our response to the petitions for reconsideration has been published and you have had the opportunity to review it. If you need more information on this subject, please feel free to contact Dorothy Nakama of my staff at this address, or by telephone at (202) 366-2992. Sincerely, Paul Jackson Rice Chief Counsel"; |
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ID: aiam2190OpenMr. F. A. McNiel, 611 Bouldin Avenue, Austin, TX, 78704; Mr. F. A. McNiel 611 Bouldin Avenue Austin TX 78704; Dear Mr. McNiel: This is in reply to your petition of November 7, 1975, 'for th correction of subsection S4.5.4 and S4.6(b) as set forth by existing Federal Motor Vehicle Safety Standard No. 108.'; It is your opinion that S4.5.4, which requires activation of stop lamp upon application of the service brakes, is design restrictive, and 'leaves no opportunity for innovation by the private sector for other solutions for the activation of a motor vehicle's stoplamps' (sic). You have suggested that S4.5.4 be amended to include at its end 'or by other beneficial means which will not impair the lighting system or the mechanical functioning of the vehicle'.; Any performance standard is design restrictive to some extent, it mus restrict manufacturers to designs that meet the desired performance requirements. Its validity as a performance standard depends on whether the restrictions of the standard are only as narrow as reasonably necessary to achieve the desired safety performance. In this case we have found that the requirement meets this test. A signal to other drivers that the service brakes are being applied is precisely the performance being sought in S4.5.4. A signal based on some other condition (e.g., vehicle deceleration) might not be as timely, or might fail altogether to operate at the critical moment (as where it is based on lifting the accelerator pedal). Since the requirement is limited to the desired safety performance, we find it valid, and your petition in this area is denied.; You also ask for an amendment of S4.6(b) to include 'rear lamps' amon those that may be flashed for signalling purposes, since you believe that conventional wiring circuits presently allow these lamps to be flashed when headlamps are flashed. When the headlamps are flashed by means of the on-off switch, it is true that rear lamps will flash. But that type of flashing is in no way restricted by the standard. The flashing intended to be regulated by S4.6(b) is by automatic means (see S3 definitions) and, except for rear turn signal lamps, these automatic devices would not be connected to rear lamp circuits. Thus, there appears to be no need for the amendment you suggest and your petition is accordingly denied.; We appreciate your continuing efforts on behalf of traffic safety. Sincerely, Robert L. Carter, Associate Administrator, Motor Vehicl Programs; |
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ID: aiam5655OpenMr. Kenneth W. Easterling Plan B Engineering, Inc. 26399 The Old Road 14-106 Stevenson Ranch, CA 91381; Mr. Kenneth W. Easterling Plan B Engineering Inc. 26399 The Old Road 14-106 Stevenson Ranch CA 91381; Dear Mr. Easterling: This responds to your letter of November 16, 1995 asking for our opinion of 'G-Lamps', ('proportional deceleration indicator lamps) intended as a rear end collision avoidance device. Your system would flash the stop lamps proportionally to the rate of deceleration. Over the years, the agency has received many requests for interpretations of the laws which it administers as they relate to deceleration warning systems. Our reply has been that it is impermissible to wire the stop lamp system so that it flashes, no matter what the purpose of the flashing. I enclose for your information, as a representative reply, a copy of our letter of July 30, 1993, to Wayne Ferguson of the Virginia Department of Transportation, which fully sets forth our views and interpretations. If you have questions about these matters, you may telephone Taylor Vinson of this office at 202-366-5263. Sincerely, Samuel J. Dubbin Chief Counsel Enclosure; |
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ID: aiam5340OpenMr. John Moore Ferrucci Nurseries Rd 1, Box 299 Piney Hollow Rd. Newfield, NJ 08344; Mr. John Moore Ferrucci Nurseries Rd 1 Box 299 Piney Hollow Rd. Newfield NJ 08344; "Dear Mr. Moore: This responds to your letter of February 4, 1994 requesting verification of a statement made by a National Highway Traffic Safety Administration (NHTSA) employee that you are allowed to install passenger seats in a van used for farm transportation if you comply with the safety regulations. In a phone conversation with Mary Versailles of my staff, you explained that you would like to add seats to the rear of a 14 foot cargo van which the nursery owns. You would be performing this work yourself. As explained below, Federal law does not apply to situations where vehicle owners alter their own vehicles. I am pleased to have this opportunity to explain our laws and regulations to you. NHTSA is authorized under the National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1381 et seq., Safety Act) to issue motor vehicle safety standards that apply to the manufacture and sale of new motor vehicles and new items of motor vehicle equipment. Section 108(a)(1)(A) of the Safety Act (15 U.S.C. 1397(a)(1)(A)) prohibits any person from manufacturing, introducing into commerce, selling, or importing any new motor vehicle or item of motor vehicle equipment unless the vehicle or equipment item is in conformity with all applicable safety standards. NHTSA has exercised its authority to establish five safety standards which could be relevant to installation of a seat in a used vehicle: Standard No. 207, Seating Systems, Standard No. 208, Occupant Crash Protection, Standard No. 209, Seat Belt Assemblies, Standard No. 210, Seat Belt Assembly Anchorages, and Standard No. 302, Flammability of Interior Materials. Standards Nos. 207, 208, 210, and 302 apply, with certain exceptions that are not relevant to your situation, to vehicles and not directly to items of equipment. Standard No. 209, however, applies to seat belt assemblies as separate items of motor vehicle equipment, regardless of whether the belts are installed as original equipment in a motor vehicle or sold as replacements. Thus, if you install new seat belts on the seats, the manufacturer is required to certify that the seat belts comply with Standard No. 209. If a seat is installed in a used motor vehicle, the seat, as an item of equipment, does not have to comply with any Federal standards. However, 108(a)(2)(A) of the Safety Act provides, in pertinent part: No manufacturer, distributor, dealer, or motor vehicle repair business 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. . . . None of these entities could install seats in your van if it caused the vehicle to no longer comply with any of the safety standards. Please note, however, that the 'render inoperative' prohibition does not apply to modifications vehicle owners make to their own vehicles. Thus, Federal law would not apply in a situation where you, as an individual vehicle owner, installed seats in your own vehicles, even if the installation were to result in the vehicle no longer complying with the safety standards. However, you should be aware that individual States have the authority to regulate modifications that individual vehicle owners may make to their own vehicles. While Federal law would not apply to a modification you make to your own vehicle, I nonetheless urge you to exercise care in installing the seats and to install seat belts on the seats. The seats and seat belts will not provide any protection to occupants if they separate from the vehicle frame in a crash. Also, you may wish to consult a private attorney familiar with the law in the State of New Jersey regarding potential liability in tort for your business in these circumstances. I hope you find this information helpful. If you have any other questions, please contact Mary Versailles of my staff at this address or by phone at (202) 366-2992. Sincerely, John Womack Acting Chief Counsel"; |
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ID: aiam2485OpenMr. William Shapiro, Regulatory Analysis Engineer, Volvo of America Corporation, Rockleigh, NJ 07647; Mr. William Shapiro Regulatory Analysis Engineer Volvo of America Corporation Rockleigh NJ 07647; Dear Mr. Shapiro: This is in reply to your letter of January 4, 1977, asking fo confirmation of your interpretation that Motor Vehicle Safety Standard No. 108 permits the installation of white reflex reflectors on the front of a passenger car.; You are correct in your interpretation. While Standard No. 108 does no require any reflex reflector on the front of a passenger car, pursuant to S4.1.3 they may be added provided that they do not impair the effectiveness of the required lighting equipment.; Sincerely,Frank A. Berndt, Acting Chief Counsel |
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ID: aiam0142OpenMr. Jack Flynn, P.O.B. Manufacturing Company, 11100 Kenwood Road, Cincinnati, OH 45242; Mr. Jack Flynn P.O.B. Manufacturing Company 11100 Kenwood Road Cincinnati OH 45242; >>>Attention: Standards Department<<< Dear Mr. Flynn: Thank you for your letter of February 21, 1969, concerning glazin materials.; I am enclosing a copy of Federal Motor Vehicle Safety Standard No. 20 and, since you manufacture and distribute sealing compounds, a copy of Federal Motor Vehicle Safety Standard No. 212.; ASA Standard Z26.1-1966, incorporated by reference in Standard No. 205 can be obtained at a cost of $3.50 from the United States of America Standards Institute, 10 East 40th Street, New York 10016.; SAE Recommended Practice J673a, August 1967, incorporated by referenc in Standard No. 205, can be obtained from the Society of Automotive Engineers, Inc., Two Pennsylvania Plaza, New York, New York, 10001.; We are in the process of changing paragraph S.3.2 of Standard No. 205 You may want to keep up with future amendments to these and other standards, therefore, I am enclosing a copy of form HS-13, Mailing List Questionnaire and subscription information for the *Federal Register*. Either or both of these will enable you to receive information in your areas of interest in all future motor vehicle safety rulemaking actions.; Sincerely, Clue D. Ferguson, Director, Office of Standards o Crash-Injury Reduction, Motor Vehicle Safety Performance Service; |
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ID: aiam4802OpenMr. Wayne Trueman Plant Manager BX-l00 International 2550 Appian Way Suite 2ll Pinole, CA 94564; Mr. Wayne Trueman Plant Manager BX-l00 International 2550 Appian Way Suite 2ll Pinole CA 94564; "Dear Mr. Trueman: This responds to your letter asking abou requirements for items to be placed in a truck's air brake system. You are particularly interested in requirements that would apply to two new products you are developing. According to your letter, the products will 'have the BX-l00 Brake Equalizer integrally combined with a Quick Release valve and another with a Relay valve.' By way of background information, the National Highway Traffic Safety Administration (NHTSA) does not provide approvals of motor vehicles or motor vehicle equipment. Under the National Traffic and Motor Vehicle Safety Act, it is the responsibility of the manufacturer to ensure that its vehicles or equipment comply with all applicable standards. The following represents our opinion based on the facts provided in your letter. NHTSA does not have any specific regulations covering brake equalizers, quick release valves, or relay valves. However, since these devices are tied into a vehicle's air brake system, they could affect a vehicle's compliance with Federal Motor Vehicle Safety Standard No. l2l, Air Brake Systems. That standard applies to almost all new trucks, buses, and trailers equipped with air brake systems. If one of your devices is installed as original equipment on a new vehicle, the vehicle manufacturer is required to certify that, with the device installed, the vehicle satisfies the requirements of all applicable safety standards. If the device is added to a previously certified new motor vehicle prior to its first sale, the person who modifies the vehicle would be an alterer of a previously certified motor vehicle and would be required to certify that, as altered, the vehicle continues to comply with all of the safety standards affected by the alteration. If the device is installed on a used vehicle by a business such as a garage, the installer would not be required to attach a certification label. However, it would have to make sure that it did not 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 should also be aware of the requirements of Federal Motor Vehicle Safety Standard No. l06, Brake Hoses, which specifies requirements for motor vehicle brake hose, brake hose assemblies, and brake hose end fittings. That standard applies to new motor vehicle equipment as well as to new motor vehicles. You should check to see if any parts of your brake devices are subject to the requirements of Standard No. l06. I am enclosing a copy of an information sheet which identifies relevant Federal statutes and NHTSA standards and regulations affecting motor vehicle and motor vehicle equipment manufacturers. I regret that we are unable to provide information concerning regulations other than those of NHTSA which may apply to your products. You may wish to contact the Federal Highway Administration's Office of Motor Carrier Standards concerning whether any of its regulations are relevant to your products. You may also wish to contact appropriate State authorities, and/or a local attorney, for advice about state and local regulations. Sincerely, Paul Jackson Rice Chief Counsel Enclosure"; |
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ID: aiam0512OpenMr. Donald R. Meton, Systems Safety Engineer, Oshkosh Truck Corporation, P.O. Box 560, Oshkosh, WI 54901; Mr. Donald R. Meton Systems Safety Engineer Oshkosh Truck Corporation P.O. Box 560 Oshkosh WI 54901; Dear Mr. Meton: This is in reply to your letter of December 1, 1971, enclosing diagram of a revised 'Vehicle Identification Plate,' and requesting our approval, based on the Certification regulations. Your submission of this revised diagram is in response to our letter to you dated November 10, 1971, wherein we disapproved of an earlier version of the identification plate due to the manner in which the axle manufacturer's ratings of the axles were presented.; In your revised diagram, you refer to the ratings in question as th axle manufacturers 'gross weight ratings.' We believe that this language is still subject to being easily confused with the GAWR required on the Certification label, and we cannot conclude that wording the label in this fashion is consistent with the Certification regulations.; In our letter of November 10 we stated, 'If you wish to provid information based on the vehicle's axle capability, we prefer that it not be represented as a vehicle or axle weight rating, but that it be described as the axle manufacturers rating of the axles.' Thus, in our opinion elimination of the words 'gross weight' from your revised label will eliminate the conflict between your vehicle identification plate and the Certification requirements.; Sincerely, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam3294OpenMr. F. L. Krall, Manager, Technical Legislation, International Harvester Company, 2911 Meyer Road, Fort Wayne, IN 46803; Mr. F. L. Krall Manager Technical Legislation International Harvester Company 2911 Meyer Road Fort Wayne IN 46803; Dear Mr. Krall: This is in reply to your letter of April 30, 1980, asking whether a ne electrical switch complies with S4.5.5 of Motor Vehicle Safety Standard No. 108.; As you have described it, the switch has three positions under two o which ('IGN/ACC' and 'ACC') the hazard warning signals will operate. The third position, however, ('OFF') is a master switch which disconnects most electrical circuits on the vehicle including hazard warning signals. You have asked whether this design is permissible under S4.5.5 which requires the vehicular hazard warning signal operating unit to 'operate independently of the ignition or equivalent switch.' You have cited as precedent a 1972 letter from this agency to Imperial Fire Apparatus approving a battery disconnect switch design. In the 1972 system the hazard signals would only be activated by turning both the master switch and the flasher to 'on'. This was acceptable to NHTSA under paragraph 3(e) of SAE J910, *Hazard Warning Signal Switch*:; >>>'... providing the master switch is separate from the ignitio switch and the hazard warning signal lamps will flash with the master switch on and the ignition switch off.'<<<; The principal difference between the two systems is that your switc 'is a part of the ignition switch assembly and not physically located elsewhere on the instrument panel.'; The intent of S4.5.5 is that the hazard warning signals operat regardless whether the ignition switch is on or off.; This intent would not appear to be met by your system whose maste switch is part of the ignition switch assembly. We suggest, therefore, that you modify your design so that the hazard warning signal circuit is added to that of the 'CB' and clock which remain operable when the master switch is in the 'off' position.; Sincerely, Frank Berndt, 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.