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: aiam4786OpenMr. Gerald F. Vinci Sun Refining and Marketing Company Tenn Penn Center 1801 Market St. Philadelphia, PA 19103-1699; Mr. Gerald F. Vinci Sun Refining and Marketing Company Tenn Penn Center 1801 Market St. Philadelphia PA 19103-1699; "Dear Mr. Vinci: This responds to your August 14, 1990 letter an telephone calls about your plans to convert the fuel system on a vehicle from gasoline to propane. You said your company ('Sun Refining') would like to purchase a new vehicle and convert it for purposes of your own research, and will not be reselling the vehicle. You ask about the requirements that would apply to the conversion. We do not have any requirements that would apply to the conversion if the conversion is made by Sun itself. The National Traffic and Motor Vehicle Safety Act and NHTSA's regulations generally do not apply to a vehicle after the vehicle is sold to a consumer (e.g., Sun) for purposes other than resale. Although the Act prohibits certain entities from tampering with or removing federally required safety features, the prohibition does not apply to modifications by a vehicle owner to his or her own vehicle. However, in the event you have the conversion done by a party other than your company, Federal law may apply. Section 108(a)(2)(A) of the Safety Act prohibits vehicle manufacturers, distributors, dealers and repair businesses from knowingly rendering inoperative federally required safety features when modifying a vehicle. I have enclosed an information sheet that discusses the application of 108(a)(2)(A) to fuel system conversions. NHTSA wishes to learn more about the safety of propane fuel systems and is considering a public announcement seeking information on various safety issues. We would, therefore, be interested in the results of your research when they're completed. Even though your conversion would not be covered by the FMVSS's, we suggest you consult State law to see if the State has requirements for propane vehicles. In addition, other Federal agencies may have regulations for your vehicle. If your vehicle would be a commercial vehicle, the regulations of the Federal Highway Administration (FHWA) may apply. I have forwarded a copy of your letter to FHWA for their reply. You might also contact the Environmental Protection Agency (EPA) for information about the conversion. EPA's general telephone number is (202) 382-2090. I hope this information is helpful. Please contact us if you have further questions. Sincerely, Paul Jackson Rice Chief Counsel Enclosure"; |
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ID: aiam3043OpenMr. Robert B. Kurre, Director of Engineering, Wayne Corporation, Industries Road, Post Office Box 1447, Richmond, IN 47374; Mr. Robert B. Kurre Director of Engineering Wayne Corporation Industries Road Post Office Box 1447 Richmond IN 47374; Dear Mr. Kurre: This responds to your June 11, 1979, letter asking whether sid push-out window exits in school buses installed pursuant to State requirements must be marked in accordance with the emergency exit requirements of S5.5.3 of Standard No. 217, *Bus Window Retention and Release*. In particular, you want to know whether these additional exits must be labeled on the bus exterior.; Section S5.5.3 of the standard requires that '[e]ach school bu emergency exit provided in accordance with S5.2.3.1 shall have the designation....on both the inside and outside surfaces of the bus. Section S5.2.3.1, in turn, requires that school buses be equipped with a rear emergency door or a side emergency door and a rear push-out window. Taken together, these two sections require that the required rear or side emergency door or rear push-out window must be appropriately marked on the inside and outside of the bus.; As the agency has frequently stated, all exits installed in schoo buses beyond those required by S5.2.3.1 need not comply with the exit requirements applicable to school bus exits. All additional exits must comply, however, with the other sections of the standard applicable to non-school buses. In this case, the additional exits would be required to be labeled in accordance with Sections S5.5.1 and S5.5.2 of the standard. Neither of these paragraphs requires the exit to be marked on the bus exterior.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam1584OpenMr. Bruce Ladson, Assistant Division Manager, Universal Tire, 14622 Southlawn Lane, Rockville, MD 20850; Mr. Bruce Ladson Assistant Division Manager Universal Tire 14622 Southlawn Lane Rockville MD 20850; Dear Mr. Ladson: This is in response to your letter of August 6, 1974, asking wha registration procedures apply to tires manufactured before May 22, 1971, but sold after that date.; We interpret Part 574 of the Code of Federal Regulations, whic establishes the tire registration requirements, as applying only to tires manufactured after the effective date of the regulation, May 22, 1971. Therefore, tires manufactured before that date need not be registered.; Yours truly, Richard B. Dyson, Acting Chief Counsel |
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ID: aiam3297OpenMr. Ralph F. Lundregan, Government Relations Manager, Avery International, Specialty Materials Division, 50-L Edwards Ferry Road, Leesburg, VA 22075; Mr. Ralph F. Lundregan Government Relations Manager Avery International Specialty Materials Division 50-L Edwards Ferry Road Leesburg VA 22075; Dear Mr. Lundregan: This is in reply to your letter of April 16, 1980, asking whether Moto Vehicle Safety Standard No. 108 allows 'reflective markings (such as red diagonal stripes on a white reflective background) [to] be used to increase visibility on the front of [trucks and heavy vehicles]'.; You are correct that Standard No. 108 does not directly address thi question. The section of the standard that appears most pertinent to it, however, is S4.1.3 prohibiting the installation as original equipment of any reflective device 'that impairs the effectiveness of lighting equipment required by' Standard No. 108. We would be concerned, for example, if reflective materials were installed in a manner that might cause confusion with headlamps or front turn signal lamps. We also wish to point out that under the standard the use of the color red is at the rear of motor vehicles and that its appearance in any other location might also cause confusion.; However, as a practical matter the use of reflective materials as truc and heavy vehicle equipment sold either as original equipment or in the aftermarket is governed by requirements of the Bureau of Motor Carrier Safety (Federal Highway Administration) which prohibit use of the color red on the front of a vehicle. You should review their requirements before proceeding with your marketing plans. (49 CFR 393.26(e)(4)).; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam4552OpenMr. Garry Gallagher Vice President Metzeler Motorcycle Tire 4520 107th SW Everett, WA 98204; Mr. Garry Gallagher Vice President Metzeler Motorcycle Tire 4520 107th SW Everett WA 98204; "Dear Mr. Gallagher: This responds to your letter seeking a interpretation of Standard No. 119, New Pneumatic Tires for Motor Vehicles Other Than Passenger Cars (49 CFR /571.119). More specifically, you asked whether the letter 'B' must appear as part of the size designation of a motorcycle tire if that tire is of bias belted construction. The answer to your question is no. As you noted in your letter, section S6.5 of Standard No. 119 sets forth the marking requirements for tires used on motor vehicles other than passenger cars, including tires for use on motorcycles. Subsection S6.5(c) states that each such tire shall be marked with 'The tire size designation as listed in the documents and publications designated in S5.1.' Section S5.1, in turn, specifies tire and rim matching information that must be provided to the public. Generally speaking, the size designation of a tire shows only the physical dimensions of that tire, not necessarily its construction. Thus, the common meaning of the term 'size designation' does not necessarily include an indication of the tire's construction type. Further, no provision of Standard No. 119 requires a tire's size designation to indicate the tire's construction type. The only reference in section S6.5 of Standard No. 119 to a tire's construction type is in subsection S6.5(i), which requires the word 'radial' to appear on the tire's sidewall if the tire is of radial construction. Therefore, in response to your question, Standard No. 119 does not require the letter 'B' to be included in the size designation of bias belted motorcycle tires. You noted that your company sometimes adds the letter 'B' to the size designation of these tires as an internal code. NHTSA has long said that manufacturers are free to include additional information on the sidewall of their tires, provided that the additional information does not obscure or confuse the meaning of the required information, or otherwise defeat the purpose of the required information. In this case, the addition of the letter 'B' to the size designation would not appear to confuse or obscure the meaning of the size designation. Hence, there would be no apparent violation of Standard No. 119 by including the letter 'B' in the size designation of bias belted motorcycle tires. If you have any further questions or need additional information on this subject, please feel free to contact Marvin Shaw of my staff at this address or by telephone at (202) 366-2992. Sincerely, Erika Z. Jones Chief Counsel"; |
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ID: aiam1750OpenHonorable John B. Anderson, House of Representatives, Washington, DC 20515; Honorable John B. Anderson House of Representatives Washington DC 20515; Dear Mr. Anderson: This responds to your request for consideration of Mr. George H Dobson's December 27, 1974, request for reconsideration of Standard No. 121, *Air brake systems*, because of its costs.; Standard No. 121 requires that newly-manufactured air-braked vehicle stop from speeds of up to 60 mph on wet and dry surfaces in the loaded and unloaded condition, without leaving a 12-foot-wide lane and without lockup of wheels above 10 mph. These performance requirements are based on a safety need for improved braking performance on air brake- equipped highway vehicles. Controlled stopping within the traffic lane is particularly important to tractor-trailer combinations to avoid 'jackknife' skids. The incompatibility of vehicle sizes can be reduced significantly by establishing equal stopping distances for trucks and passenger cars.; We have analyzed the costs and benefits to be gained in upgradin truck, bus, and trailer braking performance and have concluded that the savings in lives, injury, and property damage justify the incremental costs of this standard. Standard 121 does not require retrofit of vehicles manufactured prior to the standard's effective date.; From a cost standpoint, it is noteworthy that the arguments fo increased weight limits for commercial vehicles relied, in part, on the increased braking performance of vehicles which meet Standard No. 121. A major reason for the heavier vehicles would be to reduce the costs of transportation, and Standard No. 121 contributes directly to that goal.; As you may be aware, the NHTSA has in fact proposed postponement of th standard due to the current economic situation. Based on several hundred comments, there was persuasive evidence that a delay at this late date would create far greater dislocation in the automotive industry than would a January 1, 1975, implementation. A copy of our decision not to postpone the standard is enclosed.; Yours truly, Richard B. Dyson, Acting Chief Counsel |
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ID: aiam0842OpenMr. Richard Stevens, Cody Chevrolet, Inc. Barre-Montpelier Road, Montpelier, VT 05602; Mr. Richard Stevens Cody Chevrolet Inc. Barre-Montpelier Road Montpelier VT 05602; Dear Mr. Stevens: This is in reply to your letter of August 1, 1972, to the attention o Mr. Jerome Palisi of our White Plains, New York Office, concerning certification requirements for a vehicle which you describe and indicate will be used by a college to transport ball teams and school personnel, but will not be equipped with flashing lights or other special school bus equipment. You apparently wish to know whether you must consider this vehicle as a school bus for purposes of certification to Federal requirements.; 'School bus' is defined in the motor vehicle safety standards to mean bus 'designed primarily to carry children to and from school, but not including buses operated by common carriers in urban transportation of school children' (49 CFR 571.3). Based upon the description you provide, the NHTSA would not consider the vehicle you describe to be a school bus. For purposes of certification to Federal requirements (49 CFR Parts 567 and 568), there, 'gross vehicle weight rating' should not be computer under the minimum values specified for school buses. In addition, the requirement that vehicle type be inserted on the certification label should be met in inserting, 'BUS.'; This letter should not be construed to mean that the NHTSA takes position as to whether this vehicle need, under State law, conform to requirements for school buses. The State must determine the scope and application of its own laws.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam4102OpenWilliam Shapiro, P.E., Manager, Regulatory Affairs, Volvo Cars of North America, Rockleigh, NJ 07647; William Shapiro P.E. Manager Regulatory Affairs Volvo Cars of North America Rockleigh NJ 07647; Dear Mr. Shapiro: Thank you for your letter of November 14, 1985, requesting a interpretation of Standard No. 210, *Seat Belt Assembly Anchorages*. You explained that Volvo is planning to voluntarily add an extra anchorage for a Type 2 safety belt in the middle rear designated seating position, which is already equipped with two anchorages for a Type 1 safety belt. You asked whether the third anchorage point would have to meet the anchorage location requirements set forth in S4.3.2 of the standard. As explained below, the additional anchorage would not have to comply with the location requirements of the standard.; As you correctly pointed out, S4.1.2 allows manufacturers the option o installing anchorages for either a Type 1 or Type 2 safety belt at the center rear designated seating position. Thus, by providing anchorages for a Type 1 belt at that seating position, Volvo has met the installation requirement of S4.1.2. The agency has stated in past interpretations, such as in a March 1, 1979 letter to Ford, that systems or components installed in addition to required safety systems are not required to meet Federal safety standards, provided the additional components or systems do not destroy the ability of required systems to comply with the standards. Thus, you may install a third anchorage if it does not affect the ability of the required anchorages to meet the standard.; Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam1300OpenMr. G. Meier, Technical Service Manager, Volkswagen of America, Inc., Englewood Cliffs, NJ 07632; Mr. G. Meier Technical Service Manager Volkswagen of America Inc. Englewood Cliffs NJ 07632; Dear Mr. Meier: This is in reference to the letter you propose to send to owners o vehicles involved in Defect Notification Campaign 73-0196. (Audi 80, 1973 Model, Backing Plate on Rear Axle.); In our opinion this letter does not comply with the Defect Notificatio Regulation (49 CFR Part 577). Our reasons are as follows. While the letter refers to components involved in the defect (section 577.4(c)(1)), it does not describe the malfunction of which the owner must be informed pursuant to section 577.4(c)(2). Nor does the letter include a statement of conditions (operating or otherwise) that may cause the malfunction to occur, as required by section 577.4(c)(3). While the letter refers to a 'shimmy,' we cannot reasonably construe this to describe any more than the warning which the owner may experience (section 577.4(d)(1)(ii)). Moreover, we find your instruction to operate the vehicle at 'substantially reduced speed,' if intended to be the precautionary statement required by section 577.4(c)(4), to be so broad as to be meaningless. We believe a statement of the maximum speed at which the vehicle should be operated would be more appropriate.; The letter fails to evaluate completely the risk to traffic safety i the manner specified in section 577.4(d). In our view, when this failure is combined with the failure to describe the malfunction, the recipient of your notification is left with almost no idea of the nature of the problem with his vehicle. We find further your statement that repair parts will be at the dealers 'shortly' to be too general to conform to section 577.4(e)(1)(iii). That section clearly requires an estimate of the *day* on which parts will be available. Its purpose is to prevent the making of general statements such as that in your letter.; Finally, your letter urges the owner to take the vehicle to his deale 'immediately' only if he experiences 'rear-end shimmy.' In our view, this statement implies that without shimmy there does not exist a serious safety problem with the vehicle. Such an implication contravenes section 577.6, 'Disclaimers,' and must be deleted.; In order to conform to Part 577, your notification letter must b revised as indicated in this letter.; Sincerely, Andrew G. Detrick, Acting Director, Office of Defect Investigation, Motor Vehicle Programs; |
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ID: aiam5343OpenMr. Chris Barr Chris Barr Construction Co. 16409 S. E. Division Suite 216 Portland, Oregon 97236; Mr. Chris Barr Chris Barr Construction Co. 16409 S. E. Division Suite 216 Portland Oregon 97236; "Dear Mr. Barr: This responds to your letter of December 29, 1993 asking for an interpretation of Motor Vehicle Safety Standard No. 108 as it applies to your lighting device. You have requested confidential treatment of the matter but, in a telephone conversation of March 16, 1994, with Taylor Vinson of this office, you agreed to our practice in these matters to delete from the publicly available copy of this letter all information that would identify you, while disclosing the information necessary to render you an opinion. You plan to create 'signs, logos, emblems, accents, etc.' which will be constructed of 'sheet metal cut-outs of logos/company names,' which 'would be applied to large trucks and trailers'. The color of the LEDs would 'correspond to the safety color assigned to the panel of attachment (rear/red, side/amber- yellow)'. You note that LEDs provide a low level of illumination, for example, '100 LEDs would produce only 15 candelas of light.' You believe the ideal height is 2 feet to 3 feet. You have asked for an interpretation that this would not be prohibited under S5.1.3 of Standard No. 108. Paragraph S5.1.3 allows the installation on a new motor vehicle (i.e., one that has not been delivered to its first purchaser for purposes other than resale) of motor vehicle equipment provided that it does not impair the effectiveness of the lighting equipment required by Standard No. 108. For trailers or trucks whose overall width is 80 inches or more, the required side lighting equipment consists of amber and red side marker lamps, trailers of this width are also required to have conspicuity striping of red/white segments (which is not required for narrower trailers) applied near the lower horizontal edge. We interpret impairment as something that interferes with the function of the required equipment. The function of marker lamps and conspicuity taping is to alert drivers of other vehicles to the presence of a large vehicle in the roadway. We believe your device would not detract from this function since it also serves to call attention to the presence of a large vehicle. When equipment of this nature is not prohibited under Federal law, its permissibility must be determined under the laws of the States where the vehicle is operated. We are unable to advise you on State laws, and suggest that you consult for an opinion the American Association of Motor Vehicle Administrators, 4600 Wilson Blvd., Arlington, Va. 22203. Sincerely, John Womack 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.