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: aiam1512OpenMr. William P. Stallsmith, Jr., Senior General Attorney, Southern Railway System, Law Department, P.O. Box 1808, Washington, DC 20013; Mr. William P. Stallsmith Jr. Senior General Attorney Southern Railway System Law Department P.O. Box 1808 Washington DC 20013; Dear Mr. Stallsmith: In your letters of January 10, 1974, and May 17, 1974, you have aske if a trailer would comply with S5.8 of Standard No. 121, *Air brake systems*, ('have a parking brake system. . . when the air pressure in the supply line is at atmospheric pressure') if its parking brake system contained a valve that allows manual release of the parking brake with the supply line at atmospheric pressure but automatically resets itself when the supply line is pressurized, so that the parking brake system operates as specified by S5.8. Such a valve would permit limited motion of trailers on flat cars to cushion shock experienced during transit.; Such a valve does not appear to conflict with the intent of S5.8 tha the parking brake system apply when the supply line is at atmospheric pressure. The requirement is not intended to interfere with intentional manual release of the parking brakes after automatic application has occurred. The danger of inadvertent disablement of the parking brake system during subsequent highway travel is avoided by the automatic features which would return the system to normal operation as soon as the trailer is connected to a source of air pressure, i.e., a tractor.; Sincerely, Richard B. Dyson, Acting Chief Counsel |
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ID: aiam3495OpenMr. David McLaughlin, Dart Transit Company, 2102 University Ave., St. Paul, MN 55114; Mr. David McLaughlin Dart Transit Company 2102 University Ave. St. Paul MN 55114; Dear Mr. McLaughlin: This responds to your recent telephone conversations with Roge Fairchild of this office, in which you requested our approval for Freuhauf to change the vehicle identification numbers (VIN's) on certain of its trailers which your company purchased. As we understand your situation, your company intended to purchase and Freuhauf intended to provide you 1980 model year trailers. The trailers you actually received had Freuhauf's statements of origin indicating they are 1980 model year trailers. However, the first character of the third section of the trailers' VIN's is apparently a 'B,' thus indicating that the model year is 1981. Freuhauf reportedly wishes to correct the VIN's and use an 'A' instead of a 'B,' thus indicating the 1980 model year. We understand that these vehicles were not manufactured in serial sequence, but are scattered randomly through the manufacturer's production run.; Based on our understanding of the facts you have provided us, thi agency does not have any objection to this change being made by Freuhauf. The requirements of Federal Motor Vehicle Safety Standard No. 115 provide the manufacturers with substantial latitude regarding model year designation. S4.5.3.1 of the Standard requires that the first character of the third section of the VIN indicate the model year. S3 of the Standard defines 'model year' as 'the year used to designate a discrete vehicle model irrespective of the calendar year in which the vehicle was actually produced, so long as the actual period is less than 2 years.' In issuing the standard, the agency anticipated that once the manufacturer of a discrete vehicle model switched from designating those vehicles with a given model year (e.g., 1983) to the next model year (i.e., 1984), the manufacturer would uniformly designate all vehicles with that new model year until it switched to designating all vehicles uniformly as being produced in the following model year (i.e., 1985). More than any other user of the VIN, the manufacturer itself would benefit from this practice since it promotes the orderliness of records. However, Standard No. 115 does not actually require that this practice be followed. Further, the departure from the practice in a limited circumstance should not pose any significant practical problem for the users of the VIN's of trailers in question.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam2088OpenMr. Heinz W. Gerth, Assistant Vice President, Mercedes-Benz of North America, Inc., P.O. Box 350, Montvale, NJ 07645; Mr. Heinz W. Gerth Assistant Vice President Mercedes-Benz of North America Inc. P.O. Box 350 Montvale NJ 07645; Dear Mr. Gerth: This is in response to your letter dated May 7, 1975, regarding a apparent conflict between the inertia load requirement of Standard 206, *Door Locks and Door Retention Components*, (49 CFR 571.206, S4.1.1.3) and the test procedure incorporated by S5.1.1.2, Paragraph 5 of SAE Recommended Practice J839b. I regret the delay in responding, your letter was mistakenly routed to our Docket Section and only recently came to our attention.; The answer to your question is that the requirement of S4.1.1. controls. It is sufficient that the door latch system withstand a 30g load only in the transverse and longitudinal directions. The system is not required to withstand this load in 'any direction.'; You asked further about the acceptability of centrifuge testing t demonstrate compliance with the inertia load requirement of Standard 206. Although S5.1.1.2 mentions 'approved tests,' NHTSA has consistently refused to approve or supervise the methods manufacturers use to test to the standard. Any government inertia load compliance testing will be done in accordance with paragraph 5 of SAE Recommended Practice J839b. Mercedes-Benz, of course, may employ any method it chooses to ensure compliance with this and other safety standards, as long as the product complies. We recognize that centrifuge testing may be highly useful in a variety of applications, and I do not by any means want to discourage innovations in developmental or compliance testing.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam2285OpenMr. Tokio Iinuma, Staff, Safety, Nissan Motor Co., Ltd., 560 Sylvan Avenue, Englewood Cliffs, NJ 07632; Mr. Tokio Iinuma Staff Safety Nissan Motor Co. Ltd. 560 Sylvan Avenue Englewood Cliffs NJ 07632; Dear Mr. Iinuma: This is in response to your letter of March 17, 1976, inquiring as t the date on which a manufacturer will no longer have to comply with State bumper standards relating to property damage.; According to section 110 of the Motor Vehicle Information and Cos Savings Act (Pub. L. 92-513) once a Federal bumper standard takes effect 'no State or political subdivision thereof shall have any authority to establish or enforce with respect to any passenger motor vehicle or passenger motor vehicle equipment offered for sale any bumper standard which is not identical to' the Federal standard. The Part 581 bumper standard becomes effective September 1, 1978. As of that date, it preempts any State bumper standard which is not identical. Even though the standard becomes effective in stages, on September 1, 1978 (S5.1) and September 1, 1979 (S5.2), the preemptive effect is complete on the earlier date, September 1, 1978. Thus, a vehicle manufactured on or after September 1, 1978, and before September 1, 1979, will not have to meet a State standard, even though the State standard may be identical to the requirements of the Federal standard that become (sic) effective on September 1, 1979.; The National Highway Traffic Safety Administration proposed on Marc 12, 1976, to allow manufacturers to comply with the requirements of Part 581 before the mandatory September 1, 1978, effective date. If this proposal becomes final, any manufacturer who chooses to comply early with Part 581 and properly certifies his compliance will not be required to satisfy any non-identical State bumper standard. For purposes of that manufacturer, the Part 581 Federal bumper standard will be in effect.; Sincerely, Frank Berndt, Acting Chief Counsel |
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ID: aiam2278OpenMr. Tokio Iinuma, Staff, Safety, Nissan Motor Co., Ltd., 560 Sylvan Avenue, Englewood Cliffs, New Jersey 07632; Mr. Tokio Iinuma Staff Safety Nissan Motor Co. Ltd. 560 Sylvan Avenue Englewood Cliffs New Jersey 07632; Dear Mr. Iinuma: This is in response to your letter of March 17, 1976, inquiring as t the date on which a manufacturer will no longer have to comply with State bumper standard relating to property damage. According to section 110 od the Motor Vehicle Information and Cost Savings Act (Pub L. 92-513) once a Federal bumper standard takes effect 'no State of political subdivision thereof shall have any authority to establish or enforce with respect to any passenger motor vehicle or passenger motor vehicle equipment offered for sale any bumper standard which is not identical to' the Federal standard. The Part 581 bumper standard becomes effective September 1, 1978. As of that date, it preempts any State bumper standard which is not identical. Even though the standard becomes effective in stages, on September 1, 1978 (S5.1) and September 1, 1979 (S5.2), the preemptive effect is complete on the earlier date, September 1, 1978. Thus, a vehicle manufactured on or after September 1, 1978, and before September 1, 1979, will not have to meet a State standard, even though the State Standard may be identical to the requirements of the Federal standard that become effective on September 1, 1979.; The National Highway Traffic Safety Administration proposed on Marc 12, 1976, to allow manufacturers to comply with the requirements of Part 581 before the mandatory September 1, 1978, effective date. If this proposal becomes final, any manufacturer who chooses to comply early with Part 581 and properly certifies his compliance will not be required to satisfy any non-identical State bumper standard. For purposes of that manufacturer, the Part 581 Federal bumper standard will be in effect.; Sincerely, Frank Berndt, Acting Chief Counsel |
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ID: aiam4177OpenMr. 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: 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: aiam1673OpenMr. John W. Wooster, Wooster's Automotive, 1185 Palm Avenue, Imperial Beach, CA 92032; Mr. John W. Wooster Wooster's Automotive 1185 Palm Avenue Imperial Beach CA 92032; Dear Mr. Wooster: This is in reply to your letter of August 22, 1974, in which yo describe a particular 5-yard dump truck which you purchased and ask whether the vehicle's weight ratings are consistent with federal requirements. You describe the vehicle as having a gross vehicle weight rating of 15,000 pounds. However, when loaded with 4-5 yards of topsoil, which you state is not an abnormal load for the truck, the vehicle weight exceeds the stated gross vehicle weight rating. The weight of the unloaded vehicle is 8600 pounds.; NHTSA Certification regulations require the vehicle manufacturer t specify on the vehicle's certification label a gross vehicle weight rating, and a gross axle weight rating for each axle. The gross vehicle weight rating must be at least the sum of the unloaded vehicle weight, 150 pounds for each passenger, and the vehicle's rated cargo load (49 CFR S567.5(a)(5)). While the unloaded vehicle weight and passenger weight can be determined objectively, the rated cargo load is a figure set by the manufacturer, based on his own assessment of the vehicle's carrying capacity and the maximum load at which the vehicle may be safely operated. The NHTSA accepts such ratings by manufacturers when established in good faith. the ratings on the certification label are intended to advise purchasers of the load limitations for the vehicle and should be considered at the time of purchase. We cannot say, therefore, on the basis of the facts you present, that the vehicle failed to conform to Federal requirements. Moreover, we cannot agree with your statement that the 'size of the brakes' do not comply with federal standards. No Federal braking standards were applicable to truck manufactured at the time this truck was purchased (July 1973).; Yours truly, Richard B. Dyson, Acting Chief Counsel |
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ID: aiam3798OpenRichard W. Janney, Captain, Commander, A.S.E.D., Maryland State Police, 6601 Ritchie Highway, Glen Burnie, MD 21062; Richard W. Janney Captain Commander A.S.E.D. Maryland State Police 6601 Ritchie Highway Glen Burnie MD 21062; Dear Captain Janney: This is to follow-up your phone conversation with Stephen Oesch, of m staff concerning the agency's letter of December 20, 1983, on Standard No. 205, *Glazing Materials*. I hope that the following discussion will clarify the relationship between the requirements of Standard No. 205 and the render inoperative provision of the National Traffic and Motor Vehicle Safety Act (the Act).; Section 108(a)(2)(A) of the Act prohibits motor vehicle manufacturers distributors, dealers, and motor vehicle repair shops from knowingly rendering inoperative any device or element of design installed in compliance with a Federal motor vehicle safety standard. Standard No. 205 sets performance requirements, including requirements for light transmittance and abrasion resistance, for all glazing materials used in motor vehicles. Those performance requirements may vary depending on the vehicle type involved and the place in the vehicle where the glazing is used. For example, the luminous transmittance and abrasion resistance requirements apply to all windows in a passenger car, but only to windshield and windows to the immediate right and left of the driver in a truck or multipurpose passenger vehicle.; The application of tinting materials to glazing does not, in and o itself, constitute a violation of the render inoperative provision of section 108(a)(2)(A) of the Act. To violate section 108(a)(2)(A), manufacturers, distributors, dealers, and motor vehicle repair shops that install tinting materials must knowingly install materials which render inoperative the glazing material's compliance with Standard No. 205. Thus, for example, a motor vehicle repair shop would be in violation of section 108(a)(2)(A) of the Act if it knowingly installed in a passenger car a tinting material which would render inoperative the glazing's compliance with the abrasion resistance requirements of the standard. In each case, there will be a factual question of whether the glazing material, as tinted, will continue to meet the abrasion resistance requirements of the standard.; If you are aware of any manufacturers, distributors, dealers, or moto vehicle repair shops that are in apparent violation of section 108(a)(2)(A), please provide information concerning those apparent violations to our Office of Vehicle Safety Compliance. The information should be sent to:; >>>Mr. Francis Armstrong, Director Office of Vehicle Safety Compliance National Highway Traffic Safety Administration Room 6113 400 Seventh Street,S.W. Washington, D.C. 20590<<< I hope this discussion will be of assistance to you. If you have an further questions, please let me know.; Sincerely, Frank BErndt, Chief Counsel |
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ID: aiam1910OpenMr. Warren M. Heath, Department of California Highway Patrol, P.O. Box 898, Sacramento, CA 95804; Mr. Warren M. Heath Department of California Highway Patrol P.O. Box 898 Sacramento CA 95804; Dear Commander Heath: This is in reply to your letter of February 25, 1975, requestin several interpretations of 49 CFR Part 569, 'Regrooved Tires.' The present Regrooved Tire regulation results from a U.S. Court of Appeals decision (NAMBO v. *Volpe* 484 F.2d 1294 (D.C. Cir. 1973), cert. denied ______ U.S. _______ (1974)) which invalidated certain aspects of the previous requirements. The confusion apparent in the existing requirements results from Section 204 of the National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1424) which, when read literally, only authorizes the NHTSA to permit the sale of regrooved tires. That statutory section has since been revised (Sec. 110, Pub. L. 93-492, 88 Stat. 1470, October 27, 1974) and the NHTSA will revise Part 569 to provide a more realistic regulatory scheme than that contained in the present requirements. While we have answered as best we can the questions you raise, we believe any extensive enforcement program you plan for the requirements should be deferred until new regulations are issued.; Section 569.1 *Purpose and scope*, provides that the regulatio specifies requirements under which regrooved tires may be sold. This should not be interpreted as precluding the enforcement of the regulation against other commercial transfers, such as offering for sale, the introduction or delivery for introduction into interstate commerce, etc. Section 569.7(a) specifically prohibits those activities. Section 569.7(a) also prohibits an operator, including a public transit system, from regrooving his own tires under any circumstance, he may not, as you suggest, regroove them and sell them to others. Section 569.7(a)(1) specifically states that a person regrooving his own tires for use on motor vehicles is to be considered as delivering those tires for introduction into interstate commerce, which is a prohibited activity.; Section 569.7(b) prohibits any of the proscribed commercial activitie with respect to tires siped in the manner set forth in that section. You are apparently again misinterpreting the Scope section.; With respect to your question regarding the labeling of retreade regroovable tires, such tires must be labeled in accordance with section 569.9. There are numerous procedures by which labeling can be molded onto retreaded tires. Two with which we are familiar involve either a cutting or engraving of the matrix or the insertion of metal strips into the matrix during curing.; Yours truly, Richard B. Dyson, Assistant 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.