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: aiam3076OpenMr. Leonard Cain, Department of Education, State of Mississippi, Jackson, MS 39205; Mr. Leonard Cain Department of Education State of Mississippi Jackson MS 39205; Dear Mr. Cain: This responds to your May 7, 1979, letter asking whether any Federa law (statutes, standards, regulations or guidelines) prohibits a school district in the State of Mississippi from converting the gasoline fuel system in school buses which it owns to a butane or propane powered system. You specified that you would like this question answered both with respect to new school bus chassis equipped with the mandatory fuel integrity system and older school bus chassis not equipped with such a system. As explained below, none of the laws we administer would prohibit converting any school bus, regardless of when it was manufactured.; Under the National Traffic and Motor Vehicle Safety Act, as amended i 1974 ('the Act'), 15 U.S.C. *et seq.*, the agency has issued Motor Vehicle Safety Standard (FMVSS) No. 301-75, *Fuel System Integrity* (49 CFR 571.301-75). This standard specifies performance requirements for the fuel system of certain new motor vehicles. It applies to vehicles which use fuel with a boiling point above 32 degrees F. and which are (1) passenger cars, or (2) multipurpose passenger vehicles, trucks, or buses with a gross vehicle weight rating (GVWR) of 10,000 pounds or less, or (3) schoolbuses with a (GVWR) greater than 10,000 pounds.; New vehicles (i.e., vehicles that have not yet been sold and delivere to a purchaser for purposes other than resale) manufactured in accordance with FMVSS 301-75 may be converted to propane or butane systems. Upon the conversion of the vehicles to types of fuel systems not covered by the standard, the vehicles would cease to be subject to the standard.; Similarly, used vehicles manufactured in accordance with the standar as well as used vehicles manufactured before the effective date of the standard may be converted. Section 108(a)(2)(A) of the National Traffic and Motor Vehicle Safety Act, as amended in 1974 (the Act, 15 U.S.C. 1397(a)(2)(A)) limits tampering with the fuel systems of vehicles manufactured in accordance with FMVSS 301-75. It does not apply at all to vehicles manufactured before that standard's effective date. The section, in essence, prohibits the entities and persons listed below from knowingly removing, disconnecting or reducing performance of equipment of elements of design installed on a vehicle in accordance with applicable motor vehicle safety standards. There is no prohibition against vehicle owners modifying their own vehicles. Specifically, section 108(a)(2)(A) provides:; >>>No manufacturer, distributor, dealer or motor vehicle repai 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 ...<<<; There is no liability under section 108(a)(2)(A) in connection wit FMVSS 301-75 if one of the listed persons or entities converts a used gasoline powered vehicle into a propane powered vehicle. Modifying safety systems of a vehicle being converted from one vehicle type to another does not violate section 108(a)(2)(A) so long as the modified systems comply with the FMVSS's that would have been applicable to the vehicle had it been originally manufactured as the vehicle type to which it is being converted. For example, in converting a gasoline-powered school bus to a propane or butane-powered school bus (a vehicle type not covered by the standard), the converter could not violate section 108(a)(2)(A) with respect to FMVSS 301-75 since that standard does not apply to propane or butane-powered school buses. FMVSS 301-75 applies only to vehicles that use fuel with a boiling point above 32 degrees F, and propane and butane reach their boiling points at a lower temperature.; This means that a school district in your state would not be prohibite from converting its gasoline-powered buses, regardless of their date of manufacture, to propane or butane-powered school buses. It also means that if the school district sought to have the conversion done by a motor vehicle repair business or some other person or entity listed in Section 108(a)(2)(A), that person or entity would not be prohibited from performing the work.; Please note, however, that if a propane or butane fuel system i installed in a new vehicle, the installer would be responsible for any safety defects in the manner in which the system is installed. Sections 151 *et seq.* of the Act provide that if vehicles are found to contain a safety defect, notification of the defect must be given and the defect must be remedied. Defects in the systems themselves would be the responsibility of the manufacturer of the systems, regardless of whether they are installed in new or used vehicles.; I hope that you will find this response helpful and you have not bee inconvenienced by our delay in sending it to you.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam4619OpenMr. David S. Hughes 3150 W. 4299 So. West Valley City, UT 84119; Mr. David S. Hughes 3150 W. 4299 So. West Valley City UT 84119; "Dear Mr. Hughes: This is in reply to your letter with respect to lighting fixture you wish to install on your trailer. Your diagram shows it to be a rectangular unit that displays 'Thanks Driver' or 'Thank You' as a courtesy message. The unit may be mounted on the rear of the trailer, 'between the safety bar under the floor of the trailer', or 'directly behind the mud flaps.' In either location, you state that it 'would be out of the way of any regulated light.' You are also interested in the possibility of selling the lamp. I regret the delay in responding. This agency has no authority to 'approve' or 'disapprove' individual items of lighting equipment. We can, however, advise you as to the relationship of your device to the Federal motor vehicle safety standard on lighting administered by this agency, and the National Traffic and Motor Vehicle Safety Act under which the standard was issued. With respect to your installation of the lamp on your own truck, this agency has no regulations that would govern such an action. The acceptability of this device would be determined under the laws of the individual States in which a vehicle so equipped is registered and operated. We are unable to advise you on State law and recommend that you contact the American Association of Motor Vehicle Administrators for guidance, at 4600 Wilson Blvd., Arlington, Va. 22203. We assume that your interest in selling the lamp is as an aftermarket accessory to truck owners. If the lamp is installed by the owner of the truck, once again there are no Federal standards that apply to it, only the laws of the individual States. However, if the lamp is installed by a manufacturer, distributor, dealer, or motor vehicle repair business, under Federal law its installation must not render inoperative, either in whole or in part, any of the lighting equipment required by the Federal lighting standard. To aid these parties in avoiding a violation of that prohibition, you should ensure the wiring does not interfere with theeffectiveness of the wiring of lamps installed in accordance with Federal requirements. Without a photo, we are unsure of the relationship of the location of the courtesy device in either of the two locations you have suggested to the location of other rear lights required by Federal law, such as identification lamps, clearance lamps, stop lamps, turn signal lamps, etc., though you have stated that it is 'out of the way' of them. However, your statement indicates that you recognize the importance of ensuring that the signal from a supplementary lamp not dilute the effectiveness of Federally-required lighting equipment, and we appreciate your concern. If you have further questions, we shall be pleased to answer them. Sincerely, Stephen P. Wood Acting Chief Counsel /"; |
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ID: aiam3426OpenMr. J. E. Bingham, British Standards Institution, Test House, Maylands Avenue, Hemel Hempstead, Herts HP2 4SQ, England; Mr. J. E. Bingham British Standards Institution Test House Maylands Avenue Hemel Hempstead Herts HP2 4SQ England; Dear Mr. Bingham: This responds to your letter of March 12, 1981, concerning the strengt requirements specified in Safety Standard No. 209, *Seat Belt Assemblies*, for a dual buckle (i.e., a two buckle unit) anchored in a vehicle by one common anchorage attachment.; As explained below, I disagree with your judgment that the standar does not deal adequately with the dual buckle design. Your proposal to test the dual buckle with 5,000 pounds of force is also incorrect, the correct force is 6,000 pounds.; Section 3 of the standard defines 'hardware' as 'a metal or rigi plastic part of a seat belt assembly.' That section further defines 'attachment hardware' as 'any or all hardware designed for securing the webbing of a seat belt assembly to a motor vehicle.' As described in your letter and shown in its attached photograph, the dual buckle has a common metal anchorage attachment. Since the purpose of that metal part is to secure the webbing to the vehicle, it is considered attachment hardware.; Section 4.3 (c)(2) specifies that 'attachment hardware designed t receive the ends of two seat belt assemblies shall withstand a tensile force of at least 6,000 pounds or 2.720 kilograms without fracture. . . .' Since the common anchorage attachment is designed to receive the force created by the ends of two seat belt assemblies, it must meet the requirements of S4.3(c)(2).; You are correct that the attachment bolt is required to withstand force of at least 9,000 pounds or 4,080 kilograms under paragraph S4.3(c)(1) of the standard.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam5321OpenEric T. Stewart, Engineering Manager Mid Bus 3555 St. Johns Road P.O. Box 1985 Lima, OH 45802-1985; Eric T. Stewart Engineering Manager Mid Bus 3555 St. Johns Road P.O. Box 1985 Lima OH 45802-1985; Dear Mr. Stewart: This responds to your letter of March 17, 1994 regarding a final rule published November 2, 1992 (57 FR 49413) amending Standard No. 217, Bus Emergency Exits and Window Retention and Release. You requested clarification of the width requirement in S5.5.3(c) for retroreflective tape. You are correct that there was a discrepancy concerning the size of the tape caused by the metric conversion in the final rule. Enclosed is a copy of a July 7, 1993 letter to Mr. Thomas D. Turner of the Blue Bird Body Company which discusses this issue. As explained in that letter, we plan to issue a correction notice of the November 2, 1992 rule that would specify a minimum size of 2.5 cm for the tape. Until the correction is issued, we will not take enforcement measures regarding tape size against a manufacturer who uses 1 inch wide retroreflective tape. I hope you find this information helpful. If you have any other questions, please contact us at this address or by phone at (202) 366-2992. Sincerely, John Womack Acting Chief Counsel Enclosure; |
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ID: aiam0123OpenMr. R. M. Dahlke, Plant Manager, Rolite, Inc., Grantsburg, WI 54840; Mr. R. M. Dahlke Plant Manager Rolite Inc. Grantsburg WI 54840; Dear Mr. Dahlke: Thank you for your letter of October 24, 1968, concerning glazin materials in your recreational vehicles.; FHWA Ruling 68-1, published in the *Federal Register* on March 26 1968, (33 FR 5020) specified that campers must meet the requirements of Standard No. 205, *Glazing Materials*. Copies of FHWA Ruling 68-1 and Standard No. 205 are enclosed.; We do not have any provision for exempting certain windows from th requirements of Standard No. 205 because of their foldaway position during transport. It is true, also, that your camper could be transported in the erected condition. Therefore, all glazing materials in the camper must meet the requirements of Standard No. 205.; Travel trailers are not included in the application of Standard No 205, hence, do not have to meet the safety glazing requirements.; Sincerely, Clue D. Ferguson, Director, Office of Standards o Crash-Injury Reduction, Motor Vehicle Safety Performance Service; |
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ID: aiam0089OpenMr. William Butterfield, Product Engineer, Lodal, Incorporated, Kingsford, MI 49802; Mr. William Butterfield Product Engineer Lodal Incorporated Kingsford MI 49802; Dear Mr. Butterfield: Thank you for your letter of June 17, 1968, to the National Highwa Safety Bureau, attention of Mr. Joseph R. O'Gorman, concerning the requirements for rear identification lamps and rear clearance lamps on your EVO Refuse Packer.; Since no mounting height restrictions are specified for rea identification lamps in Motor Vehicle Safety Standard 108, these lamps may be mounted on or below the cross member between the rear wheels. Shielding may be necessary to protect the lamps.; No clearance lamp may be combined optically with any tail lamp o identification lamps. Combination rear clearance and side marker lamps may be used providing the requirements for each are met.; With respect to the requirements of Standard No. 108, I must point ou that this Bureau does not issue approval on items of lighting equipment or on vehicle designs incorporating this equipment. Therefore, the above comments are for your information only and in no way relieve the vehicle manufacturer from his responsibility for certifying that the assembled vehicle meets the requirements of Standard No. 108.; Sincerely, David A. Fay, Office of Standards on Accident Avoidance Motor Vehicle Safety Performance Service; |
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ID: aiam4863OpenMr. Stanley L. Dembecki 2303 N. 44th Street, #14-237 Phoenix, AZ 80058; Mr. Stanley L. Dembecki 2303 N. 44th Street #14-237 Phoenix AZ 80058; Dear Mr. Dembecki: This responds to your letter of March 1, 1991 asking for an 'evaluation' of your 'Flashing' center stop lamp. You have four prototypes: 'complete' one and two bulb units 'for l984 and older vehicles', and one and two 'electronic modules for all third safety brake light retrofits through 1991.' In your opinion, 'since the new safety brake light utilizes the existing brake light (retrofit) on a previously approved brake light assembly it is reasoned that any evaluation as to durability testing is not really needed.' We understand that your 'complete' unit for the older vehicles is a lamp. It is unclear whether the 'electronic module' intended for retrofit for newer vehicles is a separate lamp, or a device to be inserted into an existing lamp. However, the issue that your invention presents is not whether further testing of it is required, but whether it is permitted at all under applicable Federal statutes and regulations. We note that you would like to market it both for installation in passenger cars that already have a center lamp, and in those that do not. In short, you intend to sell the lamp/module in the aftermarket for installation on vehicles in use, rather than as original equipment installed by the manufacturer. Center highmounted stop lamps have been required by Federal Motor Vehicle Safety Standard No. 108 on all passenger cars manufactured on or after September 1, l985 (effectively the l986 model year). You indicate that your lamp flashes momentarily when the brake pedal is applied and thereafter the lamp is steady-burning. Standard No. 108 initially allowed the center lamp to be wired so as to flash with the turn signals but, since September 1, l986, has required the center lamp to be steady-burning at all times when in use. Because your invention is not steady-burning at all times, and is activated by the brake pedal and not the turn signal control, the sale or installation of the invention may be prohibited by Federal law. If this invention is a lamp, it is not a center lamp that conforms to either the initial or current requirements of Standard No. 108 for center lamps. If, on the other hand, it is a module intended for insertion into an existing lamp, its sale or installation could violate existing Federal requirements. The National Traffic and Motor Vehicle Safety Act forbids the sale of equipment that does not comply with a Federal motor vehicle safety standard. If your invention is sold as a lamp, and intended to replace original equipment center lamps on l986 and subsequent model year cars, its sale would be in violation of the Act. On the other hand, there is no similar prohibition on sale of componentry such as an electronic module that would create a noncompliance once installed. However, there is a prohibition on the installation of such componentry (as well as installation of the invention in lamp form on l986 and subsequent model year cars). The Act forbids a manufacturer, distributor, dealer, or motor vehicle repair business from rendering inoperative in whole or in part any equipment on a vehicle which has been installed pursuant to a Federal motor vehicle safety standard. We interpret this as forbidding the installation of equipment that would take a vehicle out of compliance with a Federal safety standard. With respect to l985 model and older cars, which Standard No. 108 did not require to be equipped with center lamps, sale of your lamp exclusively for use on these older vehicles would not violate the Act. However, its installation remains subject to the rendering inoperative prohibition discussed above. There are other Federal standards involving equipment to consider. For example, we would be concerned if your lamp interfered with the field of view of the interior rear view mirror, and if its installation would affect the wiring of the other stop lamps so as to interfere with their design performance. However, there should be no problem with the field of view requirements if the lamp size is comparable to the required center lamps. Once you have satisfied these concerns under Federal law, use of the lamp remains subject to the laws of the individual States in which it is used. We are unable to advise you on these laws, and suggest that you consult for an opinion the American Association of Motor Vehicle Administrators, 4600 Wilson Boulevard, Arlington, Va. 22203. Sincerely, Paul Jackson Rice Chief Counsel; |
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ID: aiam0573OpenMr. R. W. Ward, Chief Engineer, K-D Lamp Company, 1910 Elm Street, Cincinnati, OH 45210; Mr. R. W. Ward Chief Engineer K-D Lamp Company 1910 Elm Street Cincinnati OH 45210; Dear Mr. Ward: In your letter of January 20 to Mr. Vinson of this office you ask fo an interpretation of paragraph S4.7 'Replacement Equipment' of Motor Vehicle Safety Standard No. 108.; Standard No. 108 applies to motor vehicles manufactured on or afte January 1, 1972. The standard specifies items with which these vehicles must be equipped. The standard also applies to items manufactured on or after January 1, 1972, intended to replace items required by Standard No. 108 to be original equipment on these vehicles. This replacement equipment must be manufactured to conform to Standard No. 108 and certified as meeting all applicable Federal Motor vehicle safety standards.; The standard does not require conformance or certification of item intended as replacement equipment on vehicles manufactured before January 1, 1972 (sic) In this circumstance a manufacturer may continue to manufacture replacement equipment that does not meet Standard No. 108.; Sincerely, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam4530OpenAIR MAIL; AIR MAIL; Mr. Mamoru 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 July 7, 1988, with respect to a motorcycle lighting device called the 'rolling headlamp.' The headlamp is designed to have its vertical plane always perpendicular to the ground regardless of the inclination of the motorcycle. You have asked whether such a device is legally permissible. Motor Vehicle Safety Standard No. 108 does not prohibit alteration of the mounting angle of a headlamp. Although paragraph S4.3.1 requires each lamp to 'be securely mounted on a rigid part of the vehicle,' your lamp appears to be 'securely mounted' even if it is able to rotate. I hope this answers your question. Sincerely, Erika Z. Jones Chief Counsel; |
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ID: aiam1732OpenMr. Eugene Hindin, President, Gindy Mfg. Corporation, Downingtown, PA 19335; Mr. Eugene Hindin President Gindy Mfg. Corporation Downingtown PA 19335; Dear Mr. Hindin: This responds to your November 25, 1974, request for our approval o Gindy's plans to establish the date of completion of manufacture of highway trailers for purposes of compliance with Standard No. 121, *Air brake systems*, which became effective January 1, 1975.; Unfortunately there is no simple formula for a determination in advanc that a trailer is complete. For example, your determination that a vehicle is roadworthy does not establish that it is complete.; We set out what we believe are straightforward criteria in a recen letter to a person concerned with essentially the same problem as you. A copy is enclosed. It can be seen that painting, and the installation of decals, tires, or rims can be accomplished after the date of manufacture. As for special lining arrangements, or the mounting of refrigerator units, this requires a determination by you of whether the trailer is substantially complete without these fixtures.; We do appreciate your efforts to meet the requirements of the standar in good faith, as evidenced by your timely request for guidance and submission of plans. Thank you for your interest in motor vehicle safety.; Yours truly, Richard B. Dyson, Acting 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.