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: aiam4916OpenMr. Michael D. Incorvaia Manufacturing Engineering Manager Wagner Lighting P.O. Box 4650 Sevierville, TN 37864; Mr. Michael D. Incorvaia Manufacturing Engineering Manager Wagner Lighting P.O. Box 4650 Sevierville TN 37864; Dear Mr. Incorvaia: This responds further to your letter of July 3 1991, which we informed you on August 20, will be accorded confidential treatment. Paragraph 4.5 of SAE Standard J588e, Turn Signal Lamps, September 1970, states that 'failure of one or more turn signal lamps to operate should be indicated by a 'steady on', 'steady off', or by a significant change in the flashing rate of the illuminated indicator.' Electronic flashers available today provide a 'significant change' in flash rate by doubling it as an outage indication. Wagner Lighting has developed a lamp outage indication that will remain within the performance parameters of Standard No. 108, but provide an outage flash rate that appears to be slightly less than 50% greater than that of normal operation. However, there will be 'a recognized change in flashing rate.' You have asked whether these changes may be regarded as 'significant' within the meaning of SAE J588e. Your letter indicates that the design contemplated by Wagner Electric is for application in new motor vehicles. Although SAE J588e remains in effect as a replacement equipment standard, Standard No. 108 has been amended to incorporate by reference new SAE standards for turn signal lamps, and it is these standards that now apply to turn signals on new motor vehicles. Specifically, on and after December 1, l990, a motor vehicle must be manufactured to meet either SAE Standard J588 NOV84, Turn Signal Lamps for Use on Motor Vehicles Less Than 2032 mm in Overall Width, or SAE Standard J1395 APR85, Turn Signal Lamps for Use on Motor Vehicles 2032 mm or More in Overall Width. The outage indication requirement of SAE J588e was not adopted in either of the SAE standards, and has not been incorporated directly in Standard No. 108. This means that outage indication is no longer a requirement on new motor vehicles, and that Wagner Electric, under Standard No. 108, may adopt such change in flash rate as its design may call for. We are returning the tape that you enclosed. Sincerely, Paul Jackson Rice Chief Counsel Enclosure; |
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ID: aiam5604OpenMs. Yvonne Anderson Todd Vans East Highway 28 Morris, MN 56267; Ms. Yvonne Anderson Todd Vans East Highway 28 Morris MN 56267; "Dear Ms. Anderson: This responds to your letter of July 13, 1995 concerning a van which your company is modifying. The van is owned by a local school system. The school system has asked your company to raise the roof, extend the side door, install wheelchair tiedowns, and install a wheelchair lift. The vehicle was certified as a 'bus,' but your modification would reduce the seating capacity so that the vehicle would become a 'multipurpose passenger vehicle' (MPV). You asked whether this vehicle must be certified following the modifications. The answer to your question is no. By way of background information, the National Highway Traffic Safety Administration (NHTSA) is authorized to issue Federal motor vehicle safety standards that apply to the manufacture and sale of new motor vehicles. A vehicle must be certified as complying with all applicable safety standards before it can be sold or imported. After the first retail sale, there is a limit on modifications made to vehicles. Manufacturers, distributors, dealers, and repair businesses are prohibited from 'knowingly making inoperative' any device or element of design installed on or in a motor vehicle in compliance with an applicable safety standard (49 USC 30122). In general, the 'make inoperative' prohibition would require a business which modifies motor vehicles to ensure that they do not remove, disconnect, or degrade the performance of safety equipment installed in compliance with an applicable safety standard. I hope you find this information helpful. If you have any other questions, please contact Mary Versailles of my staff at this address or by phone at (202) 366-2992. Sincerely, John Womack Acting Chief Counsel"; |
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ID: aiam0056OpenMr. David A. Phelps, Jr., Engineering Services, Blue Bird Body Company, Fort Valley, GA 31030; Mr. David A. Phelps Jr. Engineering Services Blue Bird Body Company Fort Valley GA 31030; Dear Mr. Phelps: Thank you for your letter of March 19, 1968, to Mr. George C. Nield requesting a clarification of paragraphs S3.4.4 and S3.4.4.1 of Motor Vehicle Safety Standard No. 108.; In your letter you listed possible brake combinations as follows:>>>1 A vacuum over dual hydraulic brake system and a hand operated mechanical brake are provided.; 2. A full air brake system and a hand operated mechanical brake ar provided.; 3. A full air brake system with a spring loaded emergency stoppin system which is actuated at a pre-determined low air pressure level and a hand operated mechanical brake are provided.<<<; In accordance with the interpretation issued February 27, 1967, (3 F.R. 3390, copy enclosed), on 'emergency brakes,' the supplementary brake systems included in the above brake combinations are not emergency brakes. Therefore, paragraph S3.4.4 of Standard No. 108 does not require that the stop lamp be actuated upon application of these supplementary brakes.; Thank you for writing. Sincerely, David A. Fay, Office of Standards on Accident Avoidance Motor Vehicle Safety Performance Service; |
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ID: aiam5254OpenMr. Tom DeLapp Executive Coach Builders, Inc. One Executive Blvd. Springfield, MO 65802; Mr. Tom DeLapp Executive Coach Builders Inc. One Executive Blvd. Springfield MO 65802; Dear Mr. DeLapp: This responds to your letter of August 18, 1993 concerning a modification you wish to make on limousines manufactured by your company. You wish to modify the hinge assembly controlling forward and reclining movement of the front seat to provide access to the area between the front of the privacy panel and the back of the front seat. (The area contains auxiliary fuse panels and relays.) The modification would involve removal of a metal pin in the hinge assembly, allowing the seat to articulate forward to a greater degree. You asked whether Standard No. 207, Seating Systems, prohibits the removal of a limiting pin or limits forward movement of a seat back. Standard No. 207 specifies strength and other performance requirements for seats in passenger cars, multipurpose passenger vehicles, trucks, and buses. Section S4.3 of Standard No. 207 contains requirements for hinged or folding seat backs, except for passenger seats in buses or a seat adjustable only for its occupants. Section S4.3(a) requires a self-locking device for restraining the hinged or folding seat back. Section S4.3.2 contains performance requirements for this restraining device. Section S4.3 does not limit the degree of movement of a hinged or folding seat back. Thus, you may remove the limiting pin if removing it only increases the degree of movement of the seat. However, the seat must still meet the requirements of S4.3 with the pin removed. Accordingly, the seat must have a self-locking device that can withstand the force applications specified in S4.3.2.1 and acceleration specified in S4.3.2.2. I hope you find this information helpful. If you have any other questions, please contact Mary Versailles of my staff at this address or by phone at (202) 366-2992. Sincerely, John Womack Acting Chief Counsel; |
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ID: aiam2591OpenMr. Thomas E. Niehaus, 329 Miller Court, Harrison OH 45030; Mr. Thomas E. Niehaus 329 Miller Court Harrison OH 45030; Dear Mr. Niehaus: This is in response to your letter of May 2, 1977, asking whethe Federal requirements specify that motor vehicle bumpers must be equipped with a rubber stripping.; Standard No. 215, *Exterior Protection*, is a motor vehicle safet standard promulgated by the National Highway Traffic Safety Administration. That standard requires that passenger cars be capable of undergoing 5 mph front and rear impacts without incurring damage to certain specified safety systems. Motor vehicle manufacturers are permitted to meet the performance level prescribed by Standard 215 in whatever manner they choose. Most, however, have elected to meet the requirements by improving the strength of the vehicle bumper system. Although a rubber bumper strip is not specifically required by the standard, a manufacturer may use such a component as a means of meeting the prescribed performance level.; All 1977 model year cars must be capable of meeting the requirements o Standard 215. This includes those which are equipped with an optional bumper system and those which are not.; If we can provide you with any further information, please let us know. Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam4853OpenMr. Rueben K. Brown Product Engineer Crane Carrier Company P.O. Box 582891 1925 North Sheridan Tulsa, OK 74158; Mr. Rueben K. Brown Product Engineer Crane Carrier Company P.O. Box 582891 1925 North Sheridan Tulsa OK 74158; Dear Mr. Brown: This responds to your letter of March 12, 199 requesting an interpretation of the applicability of the spike stop requirement in Standard No. 105 to school buses with GVWR greater than 10,000 lbs. While school buses are required by S5.1 to be capable of meeting the requirements of S5.1.1 through S5.1.6, the spike stop requirement in S5.1.6 is only applicable to vehicles with a GVWR of 10,000 lbs. or less. Therefore, school buses with a GVWR greater than 10,000 lbs are not required to be capable of meeting the spike stop requirement. I hope this information has been helpful. If you have further questions, please contact Mary Versailles of my staff at this address or by telephone at (202) 366-2992. Sincerely, Paul Jackson Rice Chief Counsel; |
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ID: aiam2084OpenMr. C.D. McCarthy, The B.F. Goodrich Company, 500 South Main Street, Akron, Ohio 44318; Mr. C.D. McCarthy The B.F. Goodrich Company 500 South Main Street Akron Ohio 44318; Dear Mr. McCarthy: This is in response to your August 30, 1975, letter concerning th Federal Motor Vehicle Safety Standards applicable to tires which the manufacturer expects to be used in both passenger cars and trailers.; >>>S2. of Standard No. 109 specifies: This standard applies to new pneumatic tires for use on passenger car manufactured after 1948...; Similarly, S3. of Standard No. 119 specifies: This standard applies to new pneumatic tires designed for highway us on multipurpose passenger vehicles, trucks, busses, *trailers* and motorcycles manufactured after 1948...(emphasis added)<<<; These standard are mutually exclusive. Therefore, dual marking indicating compliance with the performance requirements of each are not permitted. A tire whose predominant contemplated use is on passenger cars is subject to Standard No. 109, even if the manufacturer knows it will also be marketed as a trailer tire. The choice of standard to which the tire will be certified should be made by the manufacturer. The NHTSA will accept a manufacturer's good faith determination of the applicable standard. You should note that if the tire is certified as conforming with Standard No. 119, its use as original equipment on passenger cars is prohibited by Standard No. 110. (the proposed Standard No. 120, however, would permit the use of passenger car tires on vehicles other than passenger cars, subject to a 10 percent load rating correction factor.); Please note further that a tire which is subject to Standard No. 10 must be of a size designation listed in Appendix A of that standard. Conversely, any tire labeled with a size designation which is listed in that appendix is subject to Standard No. 109.; The final paragraph of your letter discussed 'certain types and classe of equipment [determined by the NHTSA to be] non-trailers by definition.' You appear to be referring to vehicles which are not 'trailers' because they are not 'motor vehicles' or items of 'motor vehicle equipment' as the latter terms are defined by the National Traffic and Motor Vehicle Safety Act of 1966, as amended. No Federal Motor Vehicle Safety Standards apply to units which are neither motor vehicles nor motor vehicle equipment. The manufacturers of such units may equip them with tires of their choice.; Sincerely, Frank A. Berndt. Acting Chief Counsel |
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ID: aiam0543OpenMs. Reva B. Fuhrmann, Bookkeeper, Pioneer Machinery, Inc., 1725 Silverton Road, N.E., Salem, OR 97303; Ms. Reva B. Fuhrmann Bookkeeper Pioneer Machinery Inc. 1725 Silverton Road N.E. Salem OR 97303; Dear Ms. Fuhrmann: In your letter of September 15, 1972, you ask for clarification of th records that Pioneer Machinery, Inc., as a manufacturer and installer of truck hoists and racks, is required to keep.; There are several regulations issued by the National Highway Traffi Safety Administration that could apply to Pioneer. The first of these is 49 CFR Part 566, *Manufacturer Identification*. Under this regulation manufacturers of vehicles and equipment to which a Federal motor vehicle safety standard applies must file certain information with the NHTSA. Although Pioneer may not manufacture equipment subject to a standard, it could be a final-stage manufacturer, as defined by 49 CFR Part 568, *Vehicles Manufactured in Two or More Stages*, and subject to both these regulations. I enclose a copy of each. If Pioneer determines it is a 'final-stage manufacturer' then it would also be subject to the obligations of Part 568 (S 568.6) and the requirements of Part 567 (S 567.5) *Certification*, copy enclosed.; If Pioneer is a 'final-stage manufacturer,' it must file quarterl reports of production figures pursuant to 49 CFR Part 573, (S 573.5 (b)) *Defect Reports*. I have also enclosed a copy of this regulation for your review.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam5311OpenMr. Richard A. Zander AlliedSignal Automotive Proving Grounds 32104 State Road 2 New Carlisle, IN 46552; Mr. Richard A. Zander AlliedSignal Automotive Proving Grounds 32104 State Road 2 New Carlisle IN 46552; "Dear Mr. Zander: This responds to your letter asking about the fad and recovery requirements of Federal Motor Vehicle Safety Standard No. 105, Hydraulic Brake Systems. I apologize for the delay in our response. You noted that the standard requires vehicles with a GVWR of 10,000 pounds or less to be capable of making a specified number of fade stops 'at a deceleration not lower than 15 fpsps for each stop.' You stated that you are aware of a number of different understandings within the industry of the quoted phrase, and requested an interpretation as to whether vehicles must be capable of maintaining an average deceleration of at least 15 fpsps or a minimum deceleration of at least 15 fpsps. As discussed below, vehicles must be capable of maintaining a minimum deceleration of at least 15 fpsps. By way of background information, the National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1381, et seq.) authorizes the National Highway Safety Administration (NHTSA) to issue safety standards applicable to new motor vehicles and items of motor vehicle equipment. NHTSA does not, however, approve motor vehicles or motor vehicle equipment. Instead, the Safety Act establishes a 'self-certification' process under which each manufacturer is responsible for certifying that its products meet all applicable safety standards. Manufacturers must have some independent basis for their certification that a product complies with all applicable safety standards. This does not necessarily mean that a manufacturer must conduct the specific tests set forth in an applicable standard. Certifications may be based on, among other things, engineering analyses, actual testing, and computer simulations. Whatever the basis for certification, however, the manufacturer must certify that the product complies with a standard as it is written, i.e., that the vehicle will pass all applicable requirements if it is tested exactly according to the standard's test conditions and other specifications. Standard No. 105's fade and recovery test requirements are set forth in S5.1.4. These requirements must be met under the conditions prescribed in S6, when tested according to the procedures set forth in S7. See S5.1. The purpose of the fade and recovery test requirements is to help ensure that brakes retain adequate stopping capacity during and after exposure to conditions cause by prolonged or severe use, such as long, downhill driving. The standard specifies two fade and recovery tests for vehicles with a GVWR of 10,000 pounds or less. Each of the fade and recovery tests consists of three parts: (1) baseline check stops, (2) fade stops, and (3) recovery stops. The requirements for the fade stops are set forth in S5.1.4.2(a), which states that: Each vehicle with a GVWR of 10,000 lbs or less shall be capable of making 5 fade stops (10 fade stops on the second test) from 60 mph at a deceleration not lower than 15 fpsps for each stop, followed by 5 fade stops at the maximum deceleration attainable from 5 to 15 fpsps.' As you noted, S5.1.4.2(a) must be read in conjunction with S7.11.2.1, which sets forth the procedure for conducting the fade stops. It reads, in relevant part, as follows: Make 5 stops from 60 mph at 15 fpsps followed by 5 stops at the maximum attainable deceleration between 5 and 15 fpsps for each stop. ... Attain the required deceleration within 1 second and, as a minimum, maintain it for the remainder of the stopping time. Control force readings may be terminated when the vehicle speed falls to 5 mph. (Emphasis added.) The words 'required deceleration' in S7.11.2.1 refer to 15 fpsps. (That value is set forth both in S5.1.4.2(a) and the first sentence of S7.11.2.1.) Thus, in conducting fade stops, within one second of beginning a stop, a deceleration of 15 fpsps must be attained. S7.11.2.1 then specifies that, 'as a minimum,' the required deceleration (15 fpsps) must be maintained for the remainder of the stopping time. (The word 'it' in the highlighted sentence refers back to the phrase 'required deceleration.') Thus, after a deceleration of 15 fpsps is attained (within one second of beginning the stop), the deceleration cannot drop below 15 fpsps even momentarily. You stated that you are aware of the following three understandings within the industry concerning the meaning of this requirement: 1. The average deceleration for the stop must be greater than 15 fpsps. The average deceleration is calculated from one second after the stop begins to a vehicle speed of 5 mph. 2. After 1 second the deceleration can not drop below 15 fpsps even for an instant. If the deceleration drops below 15 fpsps at any time it is considered a failure even if the average deceleration is greater than 15 fpsps. 3. The average deceleration for the stop must be greater than 15 fpsps and the deceleration must be greater than 15 fpsps for at least 75% of the stop excluding the first second of the stop. Of the three understandings, the first and third are inconsistent with the plain wording of S7.11.2.1 which specifies that, after the required 15 fpsps deceleration is attained (within one second of beginning the stop), it must, as a minimum, be maintained for the remainder of the stopping time. The first and third understandings would, among other things, replace S7.11.2.1's specification that the 15 fpsps deceleration be maintained as a 'minimum' with one that it be maintained as an 'average.' The second understanding is largely correct. It is correct to state that, in conducting a fade stop, after a 15 fpsps deceleration is attained (within one second of beginning the stop), the deceleration cannot drop below 15 fpsps even for an instant. However, if the deceleration did drop below 15 fpsps, that would not necessarily indicate a 'failure' but might simply be an invalid test. As you note in your letter, a deceleration might fall below 15 fpsps because the driver did not compensate for in-stop fade. However, if a vehicle was unable to pass Standard No. 105's fade stop test requirements at the specified deceleration rates, it would not comply with the standard, notwithstanding the fact that it might be able to pass the requirements at slightly lower deceleration rates. You stated in your letter that the second understanding appears to not consider the intent of the fade procedure, the intent being that a vehicle must be capable of making multiple high deceleration stops in a short period of time without drastic changes in effectiveness. As discussed above, the purpose of the fade and recovery test requirements is to help ensure that brakes retain adequate stopping capacity during and after exposure to conditions cause by prolonged or severe use, such as long, downhill driving. If a vehicle was unable to pass Standard No. 105's fade stop test requirements at the specified deceleration rates, it would indicate inadequate stopping capability during conditions caused by prolonged or severe use, such as long, downhill driving. You also stated that in the Laboratory Test Procedure for Standard No. 105, published by NHTSA's Office of Vehicle Safety Compliance (OVSC), the data sheet for the fade stops requests the following information for the deceleration: 'Average Sust Decel.' You stated that it therefore appears that NHTSA's interpretation of the phrase 'at a deceleration not lower than 15 fpsps for each stop' is 'the average sustained deceleration.' It is incorrect to interpret the OVSC Laboratory Test Procedures as limiting the requirements of the Federal motor vehicle safety standards. I call your attention to the following note which is set forth at the beginning of the Laboratory Test Procedure: The OVSC Laboratory Test Procedures, prepared for use by independent laboratories under contract to conduct compliance tests for the OVSC, are not intended to limit the requirements of the applicable FMVSS(s). In some cases, the OVSC Laboratory Test Procedures do not include all of the various FMVSS minimum performance requirements. Sometimes, recognizing applicable test tolerances, the Test Procedures specify test conditions which are less severe than the minimum requirements of the standards themselves. Therefore, compliance of a vehicle or item of motor vehicle equipment is not necessarily guaranteed if the manufacturer limits certification tests to those described in the OVSC Laboratory Test Procedures. I am enclosing a copy of the most recent version of the Laboratory Test Procedure for Standard No. 105, in response to your request. I hope this information is helpful. If you have any further questions, please feel free to contact David Elias of my staff at this address or by telephone at (202) 366- 2992. Sincerely, John Womack Acting Chief Counsel Enclosure"; |
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ID: aiam0113OpenMr. Warren M. Heath, Commander, Engineering Section, Department of California Highway Patrol, P.O. Box 898, Sacramento, CA 95804; Mr. Warren M. Heath Commander Engineering Section Department of California Highway Patrol P.O. Box 898 Sacramento CA 95804; Dear Mr. Heath: Your letter of August 19, 1968, addressed to Mr. David A. Fay, of th National Highway Safety Bureau has been forwarded to my office for reply.; The original list of definitions of vehicles was published in th Federal Register as part of a Notice of Proposed Rule Making dated December 3, 1966. Comments were requested from interested parties. Subsequently, the definition of a multipurpose vehicle was added to the Federal Motor Vehicle Safety Standards in response to a number of comments received from industry requesting a different category for certain utility vehicles. Under the previous classification, there were a number of special purpose vehicles which did not fit into any single category. It was agreed that certain types of motor vehicles, such as Dune Buggies, the Carryall, Travelall, Compact Van, Jeep Wagoneer, Ford Bronco, and Scout type vehicles comprised a hybid (sic) class of motor vehicle which possessed the characteristics of more than one of the motor vehicle categories previously established. The 'special features' include such items as 4-wheel drive amphibious equipment. Due to the differences in body construction, load time requirements, and general vehicle purpose, it was not considered reasonable to require those dual purpose vehicles designed to carry ten persons or less to meet all of the passenger car requirements, as would have been required by the Notice. For those reasons, the new category of 'multipurpose passenger vehicle' use (sic) added to Section 245(b).; Your interest in the automotive safety program of the Federal Highwa Administration is greatly appreciated.; Sincerely, Eugene B. Laskin, Acting Director, Office of Standard Preparation, Motor Vehicle Safety Performance Service; |
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.