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: aiam3812OpenMr. H. Nakaya, Office Manager, Mazda (North America), Inc., Detroit Office, 23777 Grenfield (sic) Road, Suite 462, Southfield, MI 48075; Mr. H. Nakaya Office Manager Mazda (North America) Inc. Detroit Office 23777 Grenfield (sic) Road Suite 462 Southfield MI 48075; Dear Mr. Nakaya: This responds to your letter requesting an interpretation of Standar No. 120, *Tire Selection and Rims for Motor Vehicles Other Than Passenger Cars* (49 CFR S571.120). Specifically, you noted that section S5.2 of that standard required that certain information be labeled on the 'weather side' of each rim or wheel disc. You then offered your interpretation of the term 'weather side', and asked for my comments on that interpretation. My comment is that Standard No. 120 explicitly defines 'weather side', and that the definition of the term in Standard No. 120 is somewhat broader than your interpretation of the term.; Section S4 of Standard No. 120 contains the following definition 'Weather side' means the surface area of the rim not covered by the inflated tire. The interpretation you offered in your letter was consistent with this definition, because it would require that the information not be labeled in an area where it would be obscured by the inflated tire. However, your interpretation would also require that the information not be labeled in an area where it would be obscured by any axle mounting components, and this requirement is not contained in the definition set forth in Standard No. 120. You are free to use your narrower interpretation for your own purposes since it is consistent with the definition in the Standard, but the definition set forth in the Standard would be used to determine whether a rim complies with the requirements of the Standard.; Please feel free to contact me should you have any further questions o need more information on the requirements of Standard No. 120.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam2350OpenMr. Peter W. Mole, Pacet International, 1192 First Avenue, New York, NY 10021; Mr. Peter W. Mole Pacet International 1192 First Avenue New York NY 10021; Dear Mr. Mole:#This is in response to your June 15, 1976, questio whether Arcoflex windshield wiper blades must be certified as being in compliance with Federal motor vehicle safety standards before they may be sold as aftermarket equipment through vehicle distributors' dealer parts programs.#Standard No. 104, *Windshield Wiping and Washing Systems*, requires vehicles to be equipped with a power-driven windshield wiping system that meets specified performance requirements. It is up to vehicle manufacturers to certify that each vehicle they produce conforms to the requirements of Standard No. 104, in accordance with the certification procedures specified in 49 CFR Part 567.#Standard No. 104 is not an equipment standard, however, and is not applicable to wiper blades sold in the aftermarket. Therefore, there is no requirement that Arcoflex windshield wiper blades be certified, so long as they are not installed on vehicles as part of the wiping system prior to the first sale of the vehicle.#Sincerely, Frank A. Berndt, Acting Chief Counsel; |
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ID: aiam5495OpenThe Honorable Nick Smith Member, United States House of Representatives 121 South Cochran Avenue Charlotte, MI 48813; The Honorable Nick Smith Member United States House of Representatives 121 South Cochran Avenue Charlotte MI 48813; "Dear Mr. Smith: Thank you for your letter regarding the inquiry fro your constituent, Dave Globig of Spring Arbor College, concerning Federal requirements for the transportation of school children. I appreciate this opportunity to clarify our regulations on this subject. Mr. Globig's understanding is that Federal law 'will not allow certification of any vans made after 1995 and, after 1997, will not allow any vans to be certified.' You stated that Mr. Globig was concerned about purchasing expensive vehicles and finding out later that 'they cannot be certified.' By way of background information, 49 U.S.C. section 30101 et seq. authorizes the National Highway Traffic Safety Administration (NHTSA) to issue Federal motor vehicle safety standards (FMVSSs) for new motor vehicles, including school buses. Under that authority, NHTSA issued a comprehensive set of school bus safety standards that ensures that school buses are one of the safest forms of transportation. These standards require school buses to have safety features that include emergency exits, strengthened body panel joints, protective seating and special lamps and mirrors. Our regulations require manufacturers to self-certify the compliance of their vehicles. Our regulations also require each person selling a new school bus to sell only buses that have been certified by the manufacturer as meeting these school bus safety standards. Under our regulations, a motor vehicle, including a van, designed to carry 11 or more persons (including the driver) is classified as a 'bus.' A 'school bus' is defined as a bus that is sold 'for purposes that include carrying students to and from school or related events.' The term 'school' refers to preprimary, primary, and secondary school. With regard to Mr. Globig's belief that after 1995, Federal law will not allow any vans to be certified, there is no such prohibition going in effect. NHTSA has no requirement that would prevent a manufacturer from certifying its van as meeting all applicable FMVSSs, including the school bus standards, if the vehicle in fact complied with those standards. There are two issues we would like to bring to Mr. Globig's attention. The first issue relates to which requirements apply to the use of school vehicles. The responsibility for complying with our school bus requirements rests with the manufacturer and seller of a new bus. The school purchaser, on the other hand, has no obligation under our regulations to purchase and use a complying school bus, or any other type of vehicle. Since Federal law applies only to the manufacture and sale of a new vehicle, under our regulations, a school may use any vehicle it chooses to transport its students. NHTSA does not have the authority to prevent a school from using any of its vehicles. Once a new vehicle has been sold, the use of that vehicle becomes subject to state law. Thus, Mr. Globig should contact state officials for information about any requirements Michigan might have concerning the use of vans as school vehicles. NHTSA strongly recommends that school children only be carried in vehicles meeting Federal school bus safety standards. We have enclosed for your information a copy of Highway Safety Program Guideline No. 17, Pupil Transportation Safety. This publication was issued under the authority of the Highway Safety Act of 1966, 23 U.S.C. 401, et seq., which authorizes this agency to issue nonbinding guidelines to which states may refer in developing their own highway safety programs. Guideline 17, jointly issued by this agency and the Federal Highway Administration, provides recommendations to the states on various operational aspects of their school bus and pupil transportation safety programs. The Guideline recommends, among other things, that any school vehicle designed to carry 11 or more persons should comply with all Federal safety standards applicable to school buses at the time the vehicle was manufactured. The second issue concerns the meaning of 'school' with respect to our school bus safety standards. The school bus safety requirements apply only to new buses used to transport preprimary, primary, or secondary school children. If Mr. Globig is asking about a college, such an institution is not considered a 'school' as that term is used in our regulations. Therefore, new buses sold for transporting college students are not required to comply with the Federal school bus safety standards. I hope this information is helpful to you in responding to your constituent. Should Mr. Globig have additional questions or need additional information, he should feel free to contact Walter Myers of my staff at this address or at (202) 366-2992. Sincerely, Philip R. Recht Chief Counsel Enclosure"; |
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ID: aiam0697OpenMr. Meisner, Managing Director, Kangol Magnet Ltd., London, England; Mr. Meisner Managing Director Kangol Magnet Ltd. London England; Dear Mr. Meisner: This is in reply to your letter of April 4, 1972, in which you aske whether it is permissible for the engine starting system of a vehicle conforming to the interlock requirements of Motor Vehicle Safety Standard No. 208 to be operable when there are no occupants in the front seats by reaching through an open door or window to turn the ignition key.; Our reply is that the standard does not prohibit a system that operate in this way. Such a system is therefore permissible.; Sincerely, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam1985OpenMr. 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: This is in response to your letter dated April 2, 1975, in which yo ask several questions regarding test procedures for Federal Motor Vehicle Safety Standard No. 218, *Motorcycle Helmets*.; We are not aware of any inconsistency between Standard No. 218 and th compliance procedures that our Office of Standards Enforcement has developed in connection with it. If there were any, of course, the standard would be controlling. The standard specifies a drop height, and a 'guided free fall' from that height. We consider 'free fall' to be an objective and unambiguous physical term, meaning a movement in response to the force of gravity unimpeded by any resistance except air resistance. The requirement the equipment must be capable of meeting, therefore, refers to a fall in which the guiding method imparts no significant resistance, *i.e.*, it does not affect the results. Although in practice a perfectly frictionless guided fall may be unachievable, a manufacturer must ensure that his product would meet the requirement no matter how small the friction. An analogy is the fixed collision barrier defined in S 49 CFR 571.3, which requires a vehicle to meet a barrier crash test requirement using a barrier that absorbs no significant part of the vehicle's energy. Helmet manufacturers must assume, therefore, that the government will test their products using test fixtures that impart as little friction to the fall as possible. We therefore consider the issue of what systems were 'in general use at the time ANS Z90.1 and FMVSS 218 were written' to be irrelevant to the question of compliance.; This discussion should answer your first two questions. We do no accord any legal status to 'old' test procedures as opposed to 'new' ones. With regard to the question about correlation studies, we have not conducted any and I know of no plans to do so. Finally, Standard 218 presently covers only size C helmets because drawings and headforms for the other sizes are not yet available. Therefore, no formal compliance testing can be done on other sizes of helmets. We hope soon to publish drawings and make available models of size A, B and D headforms, at which time a date will be set for extending Standard 218 to these other sizes. Your continuing interest in motorcycle safety is greatly appreciated.; Sincerely, Frank Berndt, Acting Chief Counsel |
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ID: aiam3111OpenMr. Gerald Yingst, Stratos Corporation, 1451 N. Union Street, Middletown, PA 17057; Mr. Gerald Yingst Stratos Corporation 1451 N. Union Street Middletown PA 17057; Dear Mr. Yingst: This is in response to the questions you raised with Ms. Debra Weine of my office on July 12, 1979, about your company's plans to manufacture auxiliary gasoline tanks for passenger cars. You noted that the tanks will be designed for placement in the trunk above the existing fuel tank and that your company will act primarily as a manufacturer of these tanks but may do some installation. Specifically you asked what Federal regulations or standards would apply to the manufacturer, as well as the placement and installation of auxiliary gasoline tanks in motor vehicles. You also asked whether the we have testing facilities for such tanks and if so, whether the agency would be able to test one of your company's tanks.; The National Traffic and Motor Vehicle Safety Act, as amended 1974 (the Act) authorizes the National Highway Traffic Safety Administration (NHTSA) to issue motor vehicle safety standards applicable either to entire vehicles or to equipment for installation in vehicles. Safety Standard No. 301-75, *Fuel System Integrity*, (copy enclosed) is a vehicle standard which applies to certain vehicles, including passenger cars, that use fuel with a boiling point above 32 degrees F. The standard applies to completed vehicles rather than to fuel tanks or other fuel system components and thus is inapplicable to the manufacture of auxiliary fuel tanks.; Despite the inapplicability of Safety Standard No. 301-75 to thei manufacture, auxiliary fuel tanks must be designed and manufactured for safety. As a manufacturer of auxiliary fuel tanks, you would be subject to the defects responsibility provisions of the Act (sections 151 *et seq*., copy enclosed). Upon discovery of a safety-related defect by the Secretary of Transportation, the NHTSA Administrator, or yourself, you would be required to notify vehicle owners, purchasers, and dealers and remedy the defect.; If you install an auxiliary fuel tank in a new vehicle, prior to it first purchase in good faith for purposes other than resale, you would be a vehicle alterer under NHTSA regulations. As an alterer, you would be required by 49 CFR 567.7 to affix an additional label to the vehicle stating that, as altered, the vehicle conforms to all applicable Federal motor vehicle safety standards--including Safety Standard No. 301-75. Should a noncompliance or safety- related defect be discovered in such a vehicle, as a result of the modification, you would be required to notify vehicle owners, purchasers, and dealers and to remedy the defect.; If you installed an auxiliary gasoline tank in a used passenge vehicle, you would not be required to attach an alterer's label. However, section 108(a)(2)(A) of the Act would apply. Section 108(a)(2)(A) provides in relevant 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 vehicle safety standard. . .<<<; Thus, if you added an auxiliary tank to a used passenger vehicl manufactured in compliance with Safety Standard No. 301-75 and other standards, and in the process knowingly rendered inoperative the compliance of the fuel system or another system, you would be in violation of section 108(a)(2)(A).; I would like to point out that in addition to the Federal law discusse above there may be State product liability laws applicable to your company's proposed activities. Therefore, you may wish to consult a lawyer before your company begins manufacturing and installing auxiliary gasoline tanks.; At the present time, NHTSA is not testing auxiliary gasoline tanks, bu the agency is involved in testing vehicles to determine their compliance with Safety Standard No. 301-75. At some point the agency will probably begin testing auxiliary tanks that have been installed in vehicles, but such testing will be done only as part of our enforcement efforts. It is not a policy of the NHTSA to test and approve the products of particular manufacturers of motor vehicles or motor vehicle equipment.; In conclusion, please note that, in general, the National Highwa Traffic Safety Administration discourages the use of auxiliary fuel tanks of any kind because of the grave dangers of fire and explosion posed by their improper manufacture or installation. In the near future this agency will be making a press release warning consumers of these hazards and discouraging them from using auxiliary fuel tanks.; I hope that you will find this response helpful and that you have no been inconvenienced by our delay in sending it to you.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam4284OpenMr. Hisashi Tsujishita, Chief Co-ordinator, Technical Administration Department, Daihatsu Motor Co., Ltd., 1.Daihatsu- cho, Ikeda City, Osaka Prefecture, JAPAN; Mr. Hisashi Tsujishita Chief Co-ordinator Technical Administration Department Daihatsu Motor Co. Ltd. 1.Daihatsu- cho Ikeda City Osaka Prefecture JAPAN; Dear Mr. Tsujishita: Thank you for your letter requesting an interpretation of th requirements of three of our safety standards. This letter responds to your questions concerning Standard No. 219, *Windshield Zone Intrusion*. I regret the delay in this response. We will be responding to each of your questions concerning the other two standards in separate letters.; Your questions about Standard No. 219 concerns the requirements of S of the standard. That section provides as follows:; >>>When the vehicle traveling longitudinally forward at any speed up t and including 30 mph impacts a fixed collision barrier that is perpendicular to the line of travel of the vehicle, under the conditions of S7, no part of the vehicle outside the occupant compartment, *except windshield molding and other components designed to be normally in contact with the windshield*, shall penetrate the protected zone template, affixed according to S6, to a depth of more than one-quarter inch, and no such part of a vehicle shall penetrate the inner surface of the portion of the windshield, within the DLO, below the protected zone defined in S6. (Emphasis added.)<<<; Your specific question concerns a situation in which a windshield wipe penetrates the protected zone template during a crash test because, for example, the wiper was pushed rearward by the deformation of the cowl or the wiper switch was contacted by the test dummy during the crash, thus turning on the wiper. You noted the wiper blades are normally in contact with the windshield, but that the wiper arms only contact the windshield through the wiper blades. You asked whether the agency would consider the penetration of the wiper blade and arm into the protected zone template to be a violation of the standard. As discussed below, the answer is no, the penetration of the wiper blade and arm would not be a violation of the standard.; As you observed in your letter, the wiper blade is designed to b normally in contact with the windshield and is thus exempt from the requirements of the standard. While the arm will not be in direct contact with the windshield, the blade attached to the arm does contact the windshield. Also, the wiper arm is a small, light structure which, while not in direct contact with the windshield, is mounted only a fraction of an inch above the surface of the windshield and should pose little or no penetration hazard. Thus, the agency will consider the wiper arm, which is an integral part of the exempted wiper blade, to be exempted as well.; I you have any further questions, please let me know. Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam3541OpenMr. Shizuo Suzuki, Nissan Motor Co., Ltd., Engineering Office of North America, Suite 707, 1919 Pennsylvania Avenue, N.W., P. O. Box 57105, Washington, D.C. 20037; Mr. Shizuo Suzuki Nissan Motor Co. Ltd. Engineering Office of North America Suite 707 1919 Pennsylvania Avenue N.W. P. O. Box 57105 Washington D.C. 20037; Dear Mr. Suzuki: This responds to your letter asking whether your new wiping syste design meets the frequency requirements of Safety Standard No. 104, *Windshield Wiping and Washing System*.; By way of background information, I would point out that the agenc does not give advance approvals of vehicles or equipment. The National Traffic and Motor Vehicle Safety Act places the responsibility on the manufacturer to determine whether its vehicles or equipment comply with applicable standards. The following interpretation only represents the agency's opinion based on the information provided in your letter.; The system described in your letter operates on two settings. One o the settings provides continuous operation at a speed of about 75 cycles per minute. The wipers operate at the same speed for the second setting, but there is intermittence between each cycle. Because of the intermittence, the wipers operate only about 45 cycles per minute. As explained below, it is our opinion that such a system meets the frequency requirements of Standard No. 104.; Section S4.1.1 reads as follows: >>>S4.1.1 *Frequency*. S4.1.1.1 Each windshield wiping system shall have at least tw frequencies or speeds.; S41.1.2 One frequency or speed shall be at least 45 cycles per minut regardless of engine load and engine speed.; S41.1.3 Regardless of engine speed and engine load, the highest and on lower frequency or speed shall differ by at least 15 cycles per minute. Such lower frequency or speed shall be at least 20 cycles per minute regardless of engine speed and engine load.; S4.1.1.4 Compliance with subparagraph S4.1.1.2 and S4.1.1.3 may b demonstrated by testing under the conditions specified in section 4.1.1 and 4.1.2 of SAE Recommended Practice J903a, May 1966.; The primary issue for this interpretation is whether the system meet the requirement in section S4.1.1.1 for 'at least two frequencies or speeds.' This issue arises because the wipers operate at the same speed for the two settings, using intermittence to achieve a different number of cycles per minute. It is our opinion that the system does meet this requirement, since the language of the standard speaks of frequencies *or* speeds. While the speed may be the same for the two settings, the frequencies are different.; The system satisfies the requirements in section S4.1.1.2 and S4.1.1. that one cycle or speed be at least 45 cycles per minute, that the highest and lowest frequency or speed differ by at least 15 cycles per minute, and that the lower cycle be at least 20 cycles per minute (assuming that the requirements are met regardless of engine load and engine speed).; While your wiping system design appears to meet the frequenc requirements of Standard No. 104, we do have a possible concern about its safety. On its lower setting, between the periods of intermittence, the speed of the wiper blades would still be at a rate of about 75 cycles per minute. It is possible that operation at such a fast speed might cause chattering of the wipers when used during light precipitation. If that happened, drivers might be less likely to use their wipers during light precipitation. We suggest that you consider that possibility before going forward with your design.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam1086OpenMr. E.J. Wagner, American Retreaders' Association, Inc., P.O. Box 17203, Louisville, Kentucky 40217; Mr. E.J. Wagner American Retreaders' Association Inc. P.O. Box 17203 Louisville Kentucky 40217; Dear Mr. Wagner: This is in reply to your letter of March 20, 1973, in which you as whether, if a retreaded tire cannot meet the dimensional requirements for its original casing size, it can be considered as and labeled with a smaller size, if it meets the dimensional requirements for the smaller size.; S5.1.4 of Standard No. 117 prohibits a retread tire from having a siz designation, maximum load rating, or maximum inflation pressure greater than that originally specified on the casing. It does not prohibit a retreaded tire from having a smaller size than its casing, as long as the retreaded tire meets all the requirements for its labeled Size designation.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam1593OpenMr K.W.Berner,Manager Component Design & Development,International Harvester,Truck Division Engineering,2911 Meyer Road,Fort Wayne,Indiana 46803; Mr K.W.Berner Manager Component Design & Development International Harvester Truck Division Engineering 2911 Meyer Road Fort Wayne Indiana 46803; Dear Mr. Berner:#This is in reply to your letter of August 13, 1974, t Dr. Gregory asking for confirmation of your interpretation of S5.3.1(b) of Motor Vehicle Safety Standard No. 105.#Paragraph S5.3.1(b) states that an indicator lamp shall be activated whenever there is ' drop in the level of brake fluid in a master cylinder reservoir to less than ... one-fourth of the fluid reservoir capacity in any reservoir compartment...' This will confirm that the lamp must activate whenever the fluid in any compartment is less then one-fourth the capacity of that compartment, rather than one-fourth the total capacity of the reservoir regardless of the number of compartments.#Yours truly, Richard B. Dyson,Acting Chief Counsel; |
Request an Interpretation
You may email your request to Interpretations.NHTSA@dot.gov or send your request in hard copy to:
The Chief Counsel
National Highway Traffic Safety Administration, W41-326
U.S. Department of Transportation
1200 New Jersey Avenue SE
Washington, DC 20590
If you want to talk to someone at NHTSA about what a request for interpretation should include, call the Office of the Chief Counsel at 202-366-2992.
Please note that NHTSA’s response will be made available in this online database, and that the incoming interpretation request may also be made publicly available.