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: aiam4712OpenMr. Herbert E. Stoel 3772 Prairie Street Grandville, MI 49418; Mr. Herbert E. Stoel 3772 Prairie Street Grandville MI 49418; Dear Mr. Stoel: This is in reply to your letter to John Womack of thi Office, suggesting that the color of taillamps on motor vehicles be green. The agency is concerned about methods to effectively improve rear lighting and signaling. The issues involved include lamp size, location, operation, combinations and separation, and color. We are learning that changes in lamp function, operation, and color should be approached in a conservative fashion, so as not to confuse the operators of other vehicles. With specific respect to use of the color green on rear lighting equipment, we are aware that some research suggests a green/red color scheme may enhance driver performance. In such systems, a green lamp indicates that the accelerator pedal is applied, amber that the foot has been lifted from the accelerator pedal, and red, that the brake is being applied. Some years ago, an experiment was conducted with such a system using transit buses in the D.C. area. The results were inconclusive. Although some research suggests a possible improvement in driver performance with green/red lamps, there are no data addressing the possible driver confusion that might arise from multiple color lighting arrays. Thank you for your suggestion to enhance motor vehicle safety. Sincerely, Stephen P. Wood Acting Chief Counsel; |
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ID: aiam2451OpenMr. Donald I. Reed, Director of Engineering, Trailer Manufacturers Association, 401 North Michigan Avenue, Chicago, IL, 60611; Mr. Donald I. Reed Director of Engineering Trailer Manufacturers Association 401 North Michigan Avenue Chicago IL 60611; Dear Mr. Reed: This is in reply to your letter of October 29, 1976, asking whether th '47 Series Tite-Lite,' in our opinion, has an ''optically combined' clearance lamp function.' The lamp in question is represented as having 'two lights [that] provide 15 functions' and you have advised us that 'there are no partitions inside the multi-function lens of this lamp.'; Paragraph S4.4.1 of Motor Vehicle Safety Standard No. 108 prohibits th optical combination of clearance lamps with tail lamps and identification lamps. This means that a single bulb in the 47 Series Tite-Lite may not provide both tail lamp and clearance lamp functions. It also means that the light emitted by one bulb must not be perceived as performing the function of the other in addition to its design function. You have neither identified the function performed by both bulbs nor provided us with their candle-power output and we are unable to determine whether the lamp complies with Standard No. 108.; Sincerely, Frank A. Berndt, Acting Chief Counsel |
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ID: aiam0570OpenMr. Vincent G. Grey, Engineering Manager, Truck Trailer Manufacturers Association, 1413 K Street, N.W., Washington, DC 20005; Mr. Vincent G. Grey Engineering Manager Truck Trailer Manufacturers Association 1413 K Street N.W. Washington DC 20005; Dear Mr. Grey: This is in reply to your letter of December 20, 1971, asking whethe the Certification regulations (Docket Nos. 70-6, 70-8, 70-15) apply to pole trailers. The Docket numbers you refer to also include the regulations concerning 'Vehicles Manufactured in Two or More Stages.'; As there are no motor vehicle safety standards presently applicable t pole trailers, neither the Certification regulations (49 CFR Part 567) nor the regulations governing 'Vehicles Manufactured in Two or More Stages' (49 CFR Part 568) apply to them. As you were informally informed, however, pole trailers manufactured on or after January 1, 1973, that are equipped with air brake systems would be required to comply with Motor Vehicle Safety Standard No. 121, and their manufacturers would be required to comply with the Certification regulations and, where applicable, the regulations governing Vehicles Manufactured in Two or More Stages.; Sincerely, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam0168OpenMr. James H. Lawler, Vice President, Tank Truck Service, 15150 Dequindre, Warren, MI 48091; Mr. James H. Lawler Vice President Tank Truck Service 15150 Dequindre Warren MI 48091; Dear Mr. Lawler: Thank you for your letters dated April 7 and June 3, 1969, in which yo request clarification of the Certification Regulations that become effective with vehicles manufactured after August 31, 1969.; You are correct in your interpretation that the certification would b attached to the door post or the other locations in the cab of a vehicle that are specified in section 367.4(c). You should note, however, that the label is not a 'body certification', as you describe it, but certifies that the entire vehicle conforms to applicable safety standards.; With regard to your suggestion that the label should be placed on th body rather than the chassis of the vehicle, since in the case of your vehicles the body is likely to last longer, it has been determined that uniformity of location is of primary importance for enforcement purposes. The life of various components varies, as you know, from one vehicle to another. These regulations do not cover the situations in which used components are recombined with new ones.; Thank you for your cooperation. Sincerely, Francis Armstrong, Director, Office of Performance Analysis Motor Vehicle safety Performance Service; |
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ID: aiam0775OpenMr. Paul Weirich, General Manager, Weirich Associates, 540 Frontage Road, Northfield, IL 60093; Mr. Paul Weirich General Manager Weirich Associates 540 Frontage Road Northfield IL 60093; Dear Mr. Weirich: Thank you for your letter of July 11, 1972, inquiring about the use o plastic for an automatically closing fuel cap for automobiles.; The National Highway Traffic Safety Administration (NHTSA) has th responsibility for promulgating standards that improve the safety performance of new motor vehicles to minimize injuries and fatalities associated with the use of motor vehicles. Among the standards that have been issued is Federal Motor Vehicle Safety Standard (FMVSS) No. 301, which specifies performance requirements for the fuel tank, fuel tank filler pipe, and fuel tank connections. Like other Federal standards issued by the NHTSA, this standard is performance oriented and does not specify design requirements. This standard will shortly be amended to specify additional performance requirements including rear-end collisions and rollover. In addition, other proposals will also be issued to considerably improve fuel containment to minimize the possibility of fuel spillage resulting from additional vehicle impacts. The essential requirements pertain to demonstrations of safe fuel containment as the result of standardized vehicle crash tests. how the results are to be achieved, what materials can or cannot be used, or other design features, are left to the discretion of the motor vehicle manufacturer in order that there should be the maximum freedom for innovation and inventiveness to meet the specified safety performance. We have no restrictions in the use of plastics or other materials that meet a specified safety performance requirement.; In view of present rulemaking action to amend FMVSS No. 301, there ha been much information assembled, which is part of the public record, concerning comments from manufacturers, the interested public, and from suppliers of components. Your components, including a self-closing fuel cap and a seal within the filler pipe are interesting developments having possible contribution to improved safety. We would be pleased to have more information concerning these developments and with your permission, we would like to have copies of descriptive information to put into our public record, Docket No. 70-20, for the public and for the motor vehicle industry to see.; We should mention also that the Bureau of Motor Carrier Safety, whic regulates interstate commercial transportation of passengers and cargo, has regulations which include fuel caps. you may want to contact this organization for their current requirements. Their location is at the same address of NHTSA.; Relative to pollution, the current requirements for fuel evaporativ emission controls have resulted in motor vehicles being equipped with fuel caps that either have no vents or which vent only after certain stress develops from positive of negative internal tank pressure. You may want to contact the Environmental Protection Agency concerning their regulations. The address is 1626 K Street, N.W., Washington, D.C.; We are enclosing a copy of FMVSS No. 301, a copy of a notice proposin additional requirements, and a copy of Public Law 89-563.; We appreciate your interest in motor vehicle safety. Sincerely, Robert L. Carter, Associate Administrator, Motor Vehicl Programs; |
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ID: aiam2549OpenMr. Peter Cooper, 1228 Frick Building, Pittsburgh, PA 15219; Mr. Peter Cooper 1228 Frick Building Pittsburgh PA 15219; Dear Mr. Cooper: This responds to your March 1, 1977, question whether your client, retail tire dealer, would be in violation of the regulations of the National Highway Traffic Safety Administration (NHTSA) if he were to sell tires which do not contain an identification number as required by the NHTSA.; Paragraphs S4.3.1 and S4.3.2 of 49 CFR 571.109, Motor Vehicle Safet Standard No. 109, *New Pneumatic Tires*, requires passenger car tires to be labelled in accordance with Part 574. The absence of an identification number means that the tire is not in compliance with the requirements of Standard No. 109. Section 108(a)(1)(A) of the National Traffic and Motor Vehicle Safety Act of 1966 (the Act) (15 U.S.C. 1381 et seq.) provides in part that no person shall sell any item of motor vehicle equipment that is not in conformity with applicable standards. Since your client would be selling nonconforming tires, he would be in violation of our Act and, therefore, subject to the penalties imposed thereunder. Section 109(a) of the Act establishes a penalty of up to $1,000 for each violation of the Act, not to exceed $800,000 for any related series of violations.; Sincerely, Frank A. Berndt, Acting Chief Counsel |
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ID: aiam3849OpenBruce Henderson, Automobile Importer of America, 1735 Jefferson Davis Highway, Suite 1002, Arlington, VA 22202; Bruce Henderson Automobile Importer of America 1735 Jefferson Davis Highway Suite 1002 Arlington VA 22202; Dear Mr. Henderson: This is to follow-up on your phone conversation with Stephen Oesch o my staff concerning Safety Standard No. 201, *Occupant protection in interior impact*. Your specific question was whether a fuse box cover must comply with the requirements of section 3.3 of the standard. As explained below, a fuse box cover does not have to comply with section 3.3.; Section 3.3 of the standard provides that each 'interior compartmen door' in certain vehicle locations must remain closed when subjected to the specified performance tests. Section 571.3 defines an interior compartment door as 'any door in the interior of the vehicle installed by the manufacturer as a cover for storage space normally used for personal effects'.; The definition is meant to include such storage areas as the 'glovebox which has a large door which could fly open in a crash, and not a portion of the vehicle's electrical system such as a fuse box, which is not used as storage space.; Although not covered by the standard, we would urge a manufacture carefully to design the fuse box in such a way as to prevent injuries if it is located in an area which could be struck by an occupant in a crash.; If you have further questions, please let me know. Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam5116OpenMr. David H. B. Lee President, Lee Family, Inc. 701 East 30th Hutchinson, KS 67502; Mr. David H. B. Lee President Lee Family Inc. 701 East 30th Hutchinson KS 67502; "Dear Mr. Lee: This responds to your letter of December 29, 1992, wit respect to a 'Third Brake Light Conditions Sensor', for which you have requested a review and testing. You have also asked for our comments and advice on the sale and promotion of this product. We assume that you would like to sell it in the aftermarket to vehicle owners. We have reviewed the videotape you enclosed, and are able to advise you on this basis. The tape shows that the device is intended for installation by the owner of the vehicle, and, when installed, causes the center highmounted brake lamp to flash in proportion to braking effort (i.e., a panic or quick stop produces a higher flash rate than a stop made at a slower vehicle deceleration). Motor vehicle lighting in the United States is subject to both Federal and State requirements. The National Traffic and Motor Vehicle Safety Act and Federal Motor Vehicle Safety Standard No. 108 Lamps, Reflective Devices, and Associated Equipment are the Federal requirements to which I refer. Standard No. 108 prescribes requirements for center highmounted stop lamps that must be followed by the manufacturer of the vehicle, and met at the time the vehicle is sold by the dealer to its first owner. One of these requirements is that the center highmounted stop lamp be steady burning when it is in use. Because the Sensor creates a flashing light, a vehicle manufacturer would not be able to use it as original equipment on a vehicle subject to Standard No. 108's requirements for center lamps. These vehicles are passenger cars manufactured on and after September 1, 1985, and light trucks and vans manufactured on and after September 1, 1993. The Safety Act governs modifications to vehicles after their initial sale. This Act does not prohibit a vehicle owner from modifications that affect compliance with Standard No. 108 (or any other Federal motor vehicle safety standard). Thus, a vehicle owner may install the Sensor without violation of Federal requirements. However, we interpret the Safety Act as prohibiting the installation of the Sensor by a manufacturer, dealer, distributor, or motor vehicle repair business. Under the Act, these persons shall not 'render inoperative, in whole or in part, any device or element of design installed in accordance with a Federal motor vehicle safety standard.' In our view, this forbids the installation of equipment that would take a vehicle out of compliance with a Federal motor vehicle safety standard. However, the Act does not forbid the sale of componentry such as the Sensor which creates a noncompliance once it is installed. In summary, under Federal law, any person may sell your device, but only a person other than a manufacturer, dealer, distributor, or motor vehicle repair business may install it. We are unable to advise you as to whether the laws of any State prohibit the use of a flashing center highmounted stop lamp, and recommend that you consult the American Association of Motor Vehicle Administrators for an opinion. Its address is 4600 Wilson Boulevard, Arlington, Va. 22203. We are returning your videotape and sample Sensors. Sincerely, Paul Jackson Rice Chief Counsel Enclosures"; |
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ID: aiam2448OpenMr. Woods King, Jr., Vice President-General Counsel, Warner & Swasey, 11000 Cedar Avenue, Cleveland, OH 44106; Mr. Woods King Jr. Vice President-General Counsel Warner & Swasey 11000 Cedar Avenue Cleveland OH 44106; Dear Mr. King: This is in response to your October 29, 1976, letter concerning th status of Warner and Swasey Company with regard to the fire truck chassis that it manufactures.; Strictly speaking, the status of Warner and Swasey is simply that o 'manufacturer,' as the term is defined in Section 102(5) of the National Traffic and Motor Vehicle Safety Act of 1966, as amended (15 U.S.C. 1391,; et seq*.) (the Act). Your real concern appears to be with the lega classification of the company's products.; From the description in your letter, the chassis that are produced b Warner and Swasey for sale to fire truck apparatus manufacturers are clearly 'incomplete vehicles,' as that term is defined in S 568.3 of 49 CFR Part 568, *Vehicles Manufactured in Two or More Stages*. The current definitions of the terms 'motor vehicle,' 'motor vehicle equipment,' 'original equipment,' and 'replacement equipment' are found in Sections 102 and 159 of the Act. With these definitions, the National Highway Traffic Safety Administration considers an incomplete vehicle to be an item of original equipment, which is in turn an item of motor vehicle equipment rather than a motor vehicle.; Sincerely, Frank A. Berndt, Acting Chief Counsel |
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ID: aiam4276OpenMr. John F. Doerr, 100 Lefferts Ave. 4D, Brooklyn, NY 11225; Mr. John F. Doerr 100 Lefferts Ave. 4D Brooklyn NY 11225; Dear Mr. Doerr: This is in reply to your letter of December 12, 1986, to Secretary Dol on your 'Safety Light Warning System.' You have asked if your system 'could legally be implemented' and for advice 'how I may go about marketing this system.'; The patent drawing of your device depicts a light bar mounted in th rear window area with a green lamp in the center flanked by amber lamps, with two red lamps at the end. This system would be acceptable neither as original equipment on passenger cars, nor as replacement equipment on passenger cars manufactured on or after September 1, 1985. As of that date, Federal Motor Vehicle Safety Standard No. 108 requires passenger cars to be manufactured with a red stop lamp in the approximate location of your green lamp. There is no Federal prohibition against offering the system in the aftermarket for retrofitting on passenger cars manufactured before September 1, 1985, but the system would be subject to the laws of each State in which it would be sold or used. I understand that Oregon and California allow green-amber-red deceleration warning systems when the lamps are mounted on the rear of the car, but restrictions may exist as to their mounting in a vehicle's interior.; I hope this information is useful to you. Sincerely, Erika Z. Jones, 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.