NHTSA Interpretation File Search
Overview
NHTSA's Chief Counsel interprets the statutes that the agency administers and the standards and regulations that it issues. Members of the public may submit requests for interpretation, and the Chief Counsel will respond with a letter of interpretation. These interpretation letters look at the particular facts presented in the question and explain the agency’s opinion on how the law applies given those facts. These letters of interpretation are guidance documents. They do not have the force and effect of law and are not meant to bind the public in any way. They are intended only to provide information to the public regarding existing requirements under the law or agency policies.
Understanding NHTSA’s Online Interpretation Files
NHTSA makes its letters of interpretation available to the public on this webpage.
An interpretation letter represents the opinion of the Chief Counsel based on the facts of individual cases at the time the letter was written. While these letters may be helpful in determining how the agency might answer a question that another person has if that question is similar to a previously considered question, do not assume that a prior interpretation will necessarily apply to your situation.
- Your facts may be sufficiently different from those presented in prior interpretations, such that the agency's answer to you might be different from the answer in the prior interpretation letter;
- Your situation may be completely new to the agency and not addressed in an existing interpretation letter;
- The agency's safety standards or regulations may have changed since the prior interpretation letter was written so that the agency's prior interpretation no longer applies; or
- Some combination of the above, or other, factors.
Searching NHTSA’s Online Interpretation Files
Before beginning a search, it’s important to understand how this online search works. Below we provide some examples of searches you can run. In some cases, the search results may include words similar to what you searched because it utilizes a fuzzy search algorithm.
Single word search
Example: car
Result: Any document containing that word.
Multiple word search
Example: car seat requirements
Result: Any document containing any of these words.
Connector word search
Example: car AND seat AND requirements
Result: Any document containing all of these words.
Note: Search operators such as AND or OR must be in all capital letters.
Phrase in double quotes
Example: "headlamp function"
Result: Any document with that phrase.
Conjunctive search
Example: functionally AND minima
Result: Any document with both of those words.
Wildcard
Example: headl*
Result: Any document with a word beginning with those letters (e.g., headlamp, headlight, headlamps).
Example: no*compl*
Result: Any document beginning with the letters “no” followed by the letters “compl” (e.g., noncompliance, non-complying).
Not
Example: headlamp NOT crash
Result: Any document containing the word “headlamp” and not the word “crash.”
Complex searches
You can combine search operators to write more targeted searches.
Note: The database does not currently support phrase searches with wildcards (e.g., “make* inoperative”).
Example: Headl* AND (supplement* OR auxiliary OR impair*)
Result: Any document containing words that are variants of “headlamp” (headlamp, headlights, etc.) and also containing a variant of “supplement” (supplement, supplemental, etc.) or “impair” (impair, impairment, etc.) or the word “auxiliary.”
Search Tool
NHTSA's Interpretation Files Search
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ID: aiam2671OpenMr. Ray Sizemore, Crane Carrier Company, 1925 N. Sheridan, P.O. Box 51191, Tulsa, OK 74151; Mr. Ray Sizemore Crane Carrier Company 1925 N. Sheridan P.O. Box 51191 Tulsa OK 74151; Dear Mr. Sizemore: This responds to Crane Carrier Corporation's June 8, 1977, questio whether the maximum time limits specified by S5.1.1 of Standard No. 121, *Air Brake Systems*, for build-up of brake system air pressure from 85 to 100 psi includes the time taken to build up air pressure in an accessory reservoir (for an air starter) that is replenished only when the truck is started.; The answer to your question is no. Section S5.1.1 is a performanc requirement that assures that repeated use of the brakes during vehicle operation will not deplete the available air supply because of insufficient air compressor capacity. The purpose of this requirement only indirectly relates to the initial air pressure build-up that occurs when the vehicle is first started.; The agency's existing laboratory procedure for compliance testin provides for fully charging the air brake system (and any accessory reservoirs which charge automatically in the process) before the test is begun. The engine is shut off while brake system air pressure is reduced to a level that permits a subsequent build-up for measurement purposes. In order to properly test vehicles with air starters, the agency is modifying its procedure to keep the engine running throughout the test, so that the air starter reservoir remains fully charged throughout the measurement period.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam3963OpenMr. Don Benfield, Sales Manager, Express Yourself Company', P.O. Box 2357, Anderson, IN 46018; Mr. Don Benfield Sales Manager Express Yourself Company' P.O. Box 2357 Anderson IN 46018; Dear Mr. Benfield: Thank you for your letter of April 12, 1985, concerning stat regulations that might affect a product you are considering. You explained that your product would fit inside the rear window of a vehicle. While we do not have information on state laws, I can explain the possible effect of Federal law on your potential product. I suggest you contact vehicle safety officials in the states in which you plan to sell your product to learn of their laws.; The National Traffic and Motor Vehicle Safety Act authorizes our agenc to issue Federal Motor Vehicle Safety Standards that apply to new motor vehicles and items of motor vehicle equipment. The agency has issued Federal Motor Safety Standard No. 205, *Glazing Materials*, which sets performance requirements for glazing materials used in new motor vehicles and glazing materials sold as items of replacement equipment, a copy of the standard is enclosed. If your product is mounted on, rather than inside, the rear window, it could be affected by Standard No. 205.; The performance requirements of the standard include ones regulatin the light transmittance and abrasion resistance of glazing. Manufacturers of new vehicles must certify that the glazing in windows requisite for driving visibility conforms with the light transmittance and other requirements of the standard. If a manufacturer or dealer places your product on the rear window in a new vehicle prior to the sale of the vehicle, that person must certify that the glazing continues to be in compliance with the requirements of Standard No. 205.; In 1974, Congress amended the National Traffic and Motor Vehicle Safet Act to address the problems of persons tampering with safety equipment installed on a motor vehicle by adding section 108(a)(2)(A) to the Act. That section provides, in part, that:; >>>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 safety standard....<<<; Thus no manufacturer, distributor, dealer, or motor vehicle repai business may add material to the glazing materials of a motor vehicle, if that material would render inoperative the glazing's compliance with Standard No. 205.; Section 108(a)(2)(A) does not establish any limitations on a individual vehicle owner's ability to alter his or her own vehicle. Under Federal law, individual vehicle owners can themselves install any material they want on their vehicles, regardless of whether that material would render inoperative the compliance of the vehicle's glazing with the performance requirements of Standard No. 205.; If your product is not mounted on the window itself, it still may b affected by our standards. Standard No. 111, *Rearview Mirrors*, sets performance requirements for rearview mirrors, a copy of the standard is enclosed. The standard provides that each inside rearview mirror must provide a specified field of view to the rear of the vehicle. If the field of view of the inside mirror in a new vehicle is obstructed by anything other than head restraints or seated occupants, then an outside rearview mirror must be provided on the passenger's side of the vehicle.; Thus, if your product were mounted inside the rear window of a ne vehicle by a manufacturer or dealer at the time of its sale, and if installation of your product would mean that the inside rearview mirror would no longer comply with the applicable field of view requirements, they would have to ensure the vehicle was equipped with the necessary additional mirror required by Standard 111. Just as with Standard No. 205, section 108(a)(2)(A) would apply to the installation of your product in used vehicles by manufacturers, distributors, dealers, and motor vehicle repair shops. Thus, if your product is mounted inside the rear window and its installation would mean that the inside rearview mirror would no longer comply with the applicable field of view requirements, an outside passenger side mirror would have to be installed. Again, section 108(a)(2)(A) does not limit the actions of individual vehicle owners.; If you have further questions, please let me know. Sincerely, Jeffrey R. Miller, Chief Counsel |
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ID: aiam3349OpenMr. William Blythe, 1545 University Avenue, Palo Alto, CA 94301; Mr. William Blythe 1545 University Avenue Palo Alto CA 94301; Dear Mr. Blythe: This responds to your recent letter asking questions concerning th test procedures of Safety Standard No. 216, *Roof Crush Resistance* (49 CFR 571.216). Specifically, you are concerned with the proper applications of the test block forces specified in paragraphs S6.3 and S6.2(d) of the standard.; Your first question asks whether paragraph S6.3 allows the force on th test block to be applied 'essentially opposite the initial contact point of the roof to the block.' Paragraph S6.3 specifies that the force required by the standard shall be applied in a downward direction to the lower surface of the test device. Figure 1 of the standard illustrates this procedure and indicates that the force is to be centrally applied to the loading block. This procedure will be followed during tests by the agency to determine the compliance of particular passenger cars with Safety Standard No. 216. Therefore, we would not recommend that you apply the force opposite the initial contact point of the test block with the roof.; Paragraph S6.2(d) of the standard specifies that the initial contac point (with the roof) is on the longitudinal centerline of the lower surface of the test device and 10 inches from the forwardmost point of the centerline. Your second question asks whether this 10-inch dimension should be maintained if this places the leading edge of the test device behind the leading edge of the roof and the A-pillars. You state that this would occur with certain roof configurations which tend to be high in the center (i.e., in which the leading edge of the roof is not the highest point of the roof). A manufacturer should adhere to the 10-inch dimension even if this means the leading edge of the test device will not be forward of the A-pillar and the roof's forward edge. The test procedures specified are standardized procedures which the agency applies to all passenger cars regardless of roof configuration. Thus, the agency would maintain the 10-inch dimension even when testing a roof with a higher center than its leading edge.; I would like to point out, however, that the test procedures specifie in the safety standards only document how the agency will conduct its compliance tests. Manufacturers are not required to test vehicles according to the procedures specified. A manufacturer's responsibility is to exercise due care to ascertain that its vehicles are in fact in compliance with the standards (15 U.S.C. 1397). If you are convinced that the procedures mentioned in your letter would accurately test the compliance of a particular vehicle with Safety Standard No. 216, you are certainly permitted to use those procedures. It is up to the manufacturer, however, to determine whether it has in fact exercised due care to determine compliance.; I hope this has been responsive to your inquiry. Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam1374OpenHonorable John W. Davis, House of Representatives, Washington, DC 20515; Honorable John W. Davis House of Representatives Washington DC 20515; Dear Mr. Davis: This is in reply to your letter of December 17, 1973, on behalf of Ms Judith Davis, who has suggested the incorporation of the Federal odometer form into the bill of sale as a means of reducing paperwork in motor vehicle transactions.; Although the Federal odometer disclosure regulation requires the selle to give the buyer several items of information that we consider essential to adequate disclosure, the regulation does not require the use of a separate form. If Ms. Davis is able to include the required information in the bill of sale used by the Rome Auto Auction, she may do so. Information items that are common to the bill of sale and the disclosure statement, such as the model and make of the vehicle, would not have to be stated twice.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam4176OpenMr. Larry H. McEntire, Administrator, School Transportation, Florida Department of Education, Tallahassee, FL 32301; Mr. Larry H. McEntire Administrator School Transportation Florida Department of Education Tallahassee FL 32301; Dear Mr. McEntire: I regret the delay in responding to your letter to this office askin whether certain 'mini-vans' designed to carry a maximum of eight persons are classified by NHTSA as 'passenger cars' or 'multipurpose passenger vehicles' (MPV's), for purposes of complying with the Federal motor vehicle safety standards.; I would like to begin by clarifying that the classification of particular vehicle is determined in the first instance by its manufacturer, and not by NHTSA. Under our certification requirements (49 CFR Part 567), manufacturers are required to specify the type of their vehicles in accordance with the definitions set forth in Part 571.3 of our regulations and must certify that their motor vehicles comply with all the motor vehicle safety standards applicable to that type. We define an MPV in Part 571.3 as 'a motor vehicle ... designed to carry 10 persons or less which is constructed either on a truck chassis or with special features for occasional off-road operation.'; Information we have received regarding manufacturer certificatio discloses that manufacturers classify *cargo- carrying* models of the Ford Aerostar, and G.M. Astro and Safari as 'trucks.' A 'truck' is defined in Part 571.3 as 'a motor vehicle...except a trailer, designed primarily for the transportation of property or special purpose equipment.' We understand that *passenger* models of mini-vans designed to carry up to eight passengers utilize the same type of chassis used in truck models. It is likely, therefore, that the passenger model mini-vans you asked about would be classified as MPV's instead of passenger cars. This is verified by the 'MPV' classification given by manufacturers to the Chrysler mini-van and Toyota Van.; On a related matter, you asked for our comments on your Department' recommendation to your school boards that they not condone parents' use of conventional vans (i.e., vans not meeting Federal or State school bus safety regulations) to transport school children to school-related events. Mr. Arnold Spencer of Rockledge, Florida, recently wrote to our office concerning the above recommendation and requested us to explain how our school bus regulations apply to persons owning vans. I have enclosed a copy of our April 25, 1986, response to Mr. Spencer which you might find helpful.; I hope this information is helpful. If you have further questions please feel free to contact us.; Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam0836OpenMr. Jerome G. Abeles, Director, Product Planning & Purchasing, Sealy, Incorporated, 666 North Lake Shore Drive, Chicago, IL, 60611; Mr. Jerome G. Abeles Director Product Planning & Purchasing Sealy Incorporated 666 North Lake Shore Drive Chicago IL 60611; Dear Mr. Abeles: This is in reply to your letter of August 10, 1972, concerning th application of Motor Vehicle Safety Standard No. 302, 'Flammability of Interior Materials', to mattress assemblies.; Paragraph S4.1 of the Standard lists mattress covers only. This doe not include the complete mattress assembly. Accordingly, you are correct in your assumption that only the mattress covers must meet the burn rate requirement of Paragraph S4.3. You are also correct in your assumption that mattress assemblies which are not designed to absorb energy on contact with occupants in crash situations are not subject to the Standard.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam3719OpenMr. Charles Jayne, Tire Manager, J-B Purchasing Corporation, P.O. Box 692, Auburn, NY 13021; Mr. Charles Jayne Tire Manager J-B Purchasing Corporation P.O. Box 692 Auburn NY 13021; Dear Mr. Jayne: This responds to your recent letter asking about the requirements of 4 CFR Part 574, *Tire Identification and Recordkeeping*. You noted that your company currently retreads tires for its own use, and that you soon plan to retread tires for sale to others. You asked if the tires you retread for your own use need to be identified with a tire identification number. The answer is no.; Section 574.5 of the Tire Identification and Recordkeeping regulatio provides, in part, that, 'Each tire retreader, *except tire retreaders who retread tires for their own use*, shall conspicuously label one sidewall of each tire he retreads by permanently molding or branding into or onto the sidewall, ...a tire identification number....' Your question concerns a situation in which a tire retreader retreads some tires for his own use and some tires for sale or lease to others. To answer your question, it is helpful to examine the purpose of the identification requirement.; The purpose of having the tire identification number labeled on th sidewall of retreaded tires is twofold. First, it enables this agency and the user of the retreaded tire to identify the retreader of the tire in the event of some safety problem with the tire. Second, it enables the tire retreader to accurately identify the retreaded tires it may have to recall. In the case of tires offered for sale or use outside your company, it is plain that both these purposes would be served by having the tire identification number on the sidewall. Therefore, Part 574 requires that each such tire have a tire identification number on one sidewall.; However, with respect to tires retreaded for the retreader's own use it is obvious who retreaded the tire, whether or not a tire identification number appears on the sidewall. Hence, the first purpose listed above would not be served by having the tire identification number on the sidewall of these tires. Further, the retreader can inspect all of the retreaded tires it uses to determine if any are subject to its recall, and assure adequate remedy for those which are within the recall, without publicizing the identification numbers of those tires. Thus, the second purpose set forth above also would not be furthered by having the tire identification number on the sidewall of these tires. Please note, however, that any tire not marked with a tire identification number can never legally be sold or otherwise offered for use outside of your company.; Should you have any further questions or need additional informatio about this topic, please contact Steve Kratzke of my staff at (202) 426-2992.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam1724OpenNancy Kolodny, Esq., Office of the General Counsel, Ford Motor Company, The American Road, Dearborn, MI 48121; Nancy Kolodny Esq. Office of the General Counsel Ford Motor Company The American Road Dearborn MI 48121; Dear Ms. Kolodny: This is in reply to your letter of June 10, 1975, asking whether Moto Vehicle Safety Standard No. 108 preempts Section 25950 of the California Vehicle Code with respect to Mercury Monarch taillamps.; Section 25950 requires in pertinent part that all lamps visible fro the rear of a vehicle be red, 'whether lighted or unlighted', except that taillamps may be white when unlighted. Standard No. 108 requires passenger car taillamps to be 'red' (Table III), and 'the taillamp indication' to be red (SAE Standard J585, *Tail Lamps*, June 1966, incorporated by reference into Standard No. 108). The taillamps on the Mercury Monarch are covered with amber lenses. Although the lamp meets the color and photometric requirements of Standard No. 108 when lighted, California is of the opinion that use of the amber lens is prohibited by Section 25950.; Section 103(d) of the National Traffic and Motor Vehicle Safety Act o 1966 prohibits a State from establishing or continuing in effect any motor vehicle safety standard applicable to the same aspect of performance of a vehicle or equipment item as a Federal standard which is not identical to it. We interpret Standard No. 108 as requiring only that the color of the taillamp 'indication' be red. The method by which this is accomplished is left to the vehicle manufacturer. The indication could be provided by a combination of a white bulb and a red lens (the conventional taillamp), a red bulb and white lens (permitted by California) or, as in your case, a red bulb and an amber lens. Although the color of the taillamp lens is not directly specified by Standard No. 108, the performance of the lamp as an assembly is covered in detail by the standard, and we consider that the color aspects of taillamps are within the scope of these requirements. If the lamp assembly complies with the Federal standard, then a State may not prohibit its use. We therefore find that in this instance 49 CFR 571.108, Federal Motor Vehicle Safety Standard No. 108, renders void the requirement of Section 25950 of the California Vehicle Code that unlighted taillamps be colored red.; Sincerely, James C. Schultz, Chief Counsel |
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ID: aiam4526OpenMr. Paul Scully Vice President Peterson Manufacturing Co. 4200 East 135th St. Grandview, MO 64030; Mr. Paul Scully Vice President Peterson Manufacturing Co. 4200 East 135th St. Grandview MO 64030; Dear Mr. Scully: This is in reply to your letter of April 22, l988 asking for a clarification of a letter that this Office sent Wesbar Corporation on March 16, 1988, with respect to the term 'effective projected luminous area.' Wesbar had asked whether it could include the 'illuminated (by the turn signal bulb) reflex reflector portion of the turn signal lens' (Wesbar's language) in its calculation of the l2 square inch minimum effective projected luminous area required by S4.1.1.7 of Safety Standard No. 108. We replied that it could, assuming that the light shines through the reflector. You have pointed out that although a small amount of light escapes through a reflex reflector, the reflector is designed to return light from an outside source, rather than to direct light from a source inside the lamp, and that heretofore agency interpretations (e.g. on October 28, 1970, and October 28, 1979) had expressly excluded reflex reflectors from areas included in the calculation of effective projected luminous area. Reflex reflectors are also excluded from the term by SAE J387 Terminology. We appreciate your calling this matter to our attention. Previous interpretations by this Office clearly indicate that a 'reflex reflector' is not to be included in the calculation of effective projected luminous area. We also note that the SAE definition (paragraph 2, SAE J594f, January l977) is incorporated by reference into Standard No. 108, stating that this item of equipment is one that provides an indication of vehicle presence by reflected light (rather than projected light). We are providing a copy of this letter to Wesbar so that it will be apprised of our reevaluation, and our conclusion that the reflex reflector portion of a lens cannot be included in the calculations of the projected luminous lens area. I hope this clarifies the matter for you. Sincerely, Erika Z. Jones Chief Counsel; |
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ID: aiam0565OpenMr. E. R. Sternberg, Director, Engineering Planning - Truck Group, White Motor Corporation, 100 Brieview Plaza, Cleveland, OH 44144; Mr. E. R. Sternberg Director Engineering Planning - Truck Group White Motor Corporation 100 Brieview Plaza Cleveland OH 44144; Dear Mr. Sternberg:#This is in reply to your letter of January 3, 1972 requesting an interpretation of S4.2.2 of Standard No. 101, as it applies to your proposed method of compliance for push-pull controls.#S4.2.2 requires, in pertinent part, that 'Identification shall be provided for each function of any . . . heating and air conditioning system control, and for the extreme positions of any such control that regulates a function over a quantitative range.' Identification such as that shown in your Example (2) would meet Standard No. 101, while the identification provided in Example (3) would not. Legends such as 'Pull on' and 'Push off' might more clearly indicate control positions than your suggested 'Max (out)' and 'Off (in).' The control which operates both the defroster and heater must identify both functions, 'Defrost' as indicated is insufficient. Legends such as 'Pull to defrost' and 'Push for heat' would be acceptable for conformance.#Sincerely, Richard B. Dyson, Assistant 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.