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: aiam0490OpenMr. Thomas G. Maylone, General Manager, Trike Motor Company, P.O. Box 1044, Pontiac, MI 48056; Mr. Thomas G. Maylone General Manager Trike Motor Company P.O. Box 1044 Pontiac MI 48056; Dear Mr. Maylone: You wrote some time ago to request information concerning th application of various motor vehicle safety standards to passenger cars with curb weights of less than 1,000 pounds. Contrary to the information you obtained from *Motor Trend*, this category of passenger cars is still exempt from the standards. There is a possibility that at some future date the exemption granted by 571.7(a) will be changed or revoked, but any such action can be taken only after opportunity for public comment.; Please advise us if you feel it necessary to have your remainin questions answered.; Sincerely, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam2157OpenMargaret A. Freeston, Consumer Product Safety Commission, Washington, DC, 20207; Margaret A. Freeston Consumer Product Safety Commission Washington DC 20207; Dear Ms. Freeston: This is in response to your letter of February 10, 1976, in which yo request our opinion concerning the applicability of Federal Motor Vehicle Safety Standard No. 302 to mattresses.; You are correct in saying that the amendment to S4.2 of Standard No 302, promulgated on March 31, 1975 (40 FR 14318), extends the coverage of the standard to '(a)ny portion of a single or composite material which is within 1/2 inch of the occupant compartment air space...' S4.1 of the standard provides, however, that '(t)he portions described in S.4.2 of the following components shall meet the requirements (of the standard)....' S4.1 then lists the components to which the standard applies. While mattress covers are included in the listing, mattresses are not. Consequently, Standard No. 302 does not apply to mattresses as such.; You should be aware that a notice of proposed rulemaking was als issued on March 31, 1975 (40 FR 14340) proposing that any material within 1/2 inch of the occupant compartment air space meet the requirements of the standard. Should this proposal be adopted, mattresses would fall within the purview of Standard No. 302. I have enclosed a copy of the proposed rule for your further information.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam4980OpenMr. Robert Salton Performance Friction Corp. 83 Carbon Metallic Highway P.O. Box 819 Clover, S.C. 29710-0819; Mr. Robert Salton Performance Friction Corp. 83 Carbon Metallic Highway P.O. Box 819 Clover S.C. 29710-0819; "Dear Mr. Salton: This responds to your request for an interpretatio of Federal Motor Vehicle Safety Standard No. 105, Hydraulic Brake Systems (49 CFR 571.105). You stated that you are unclear about the pedal force requirements during the first fade and recovery test baseline check stops, and that an interpretation would make it clear exactly what calculation of pedal effort is used to verify compliance during the fade and recovery check stops. You also asked what values of pedal effort would be 'considered non-compliance,' i.e., whether peak, average or sustained control force must be within the specified limits under section S5.1.4.1. You indicated in a telephone conversation with Edward Glancy of my staff that you are primarily interested in the requirements for vehicles with a GVWR less than 10,000 pounds. Your questions are addressed below. By way of background information, the National Highway Traffic Safety Administration does not provide approvals of motor vehicles or motor vehicle equipment. Under the National Traffic and Motor Vehicle Safety Act, it is the responsibility of the manufacturer to ensure that its vehicles or equipment comply with applicable standards. A manufacturer then certifies that its vehicles or equipment comply with the applicable standards. Standard No. 105's fade and recovery 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 standard specifies two fade and recovery tests, each of which consists of three parts: (1) baseline check stops or snubs, (2) fade stops or snubs (the heating cycle), and (3) recovery stops or snubs. The pedal force requirements for the baseline check stops or snubs are set forth in S5.1.4.1, which reads as follows: The control force used for the baseline check stops or snubs shall be not less than 10 pounds, nor more than 60 pounds, except that the control force for a vehicle with a GVWR of 10,000 pounds or more may be between 10 pounds and 90 pounds. S5.1.4.1 must be read in conjunction with S7.11.1, which sets forth the procedure for the baseline check stops or snubs. S7.11.1.1 provides the following procedure for vehicles with a GVWR of 10,000 pounds or less: Make three stops from 30 mph at 10 fpsps for each stop. Control readings may be terminated when vehicle speed falls to 5 mph. Average the maximum brake control force required for the three stops. The baseline check stops or snubs are thus made at a constant deceleration (10 fpsps), with the control force varying as necessary to maintain that constant deceleration. Under S5.1.4.1, the control force is required to stay within a prescribed range (10 pounds to 60 pounds for vehicles with a GVWR less than 10,000 pounds) throughout the entire stop or snub (from the time in which application is started until the vehicle speed falls to 5 mph, other than the initial momentary period it takes to go from 0 to 10 pounds). Thus, compliance with S5.l.4.1 is not determined based on peak, average or sustained control force. Instead, for a vehicle to comply with this test, the control force must never fall below 10 pounds or be above 60 pounds during any part of the test (for the period described above). Your other question concerned how calculation of pedal effort during the baseline check stops or snubs is used to verify compliance during the fade and recovery check stops. As indicated above, S7.11.1.1 specifies that an average is taken of the maximum control force for the three stops. The term 'maximum' refers to the peak control force for each of the stops. I note that this average is not related to whether the vehicle complies with S5.1.4.1. Instead, as discussed below, this average establishes a baseline control force, which is used to derive certain of the control force limits for the recovery stops. The requirements for the recovery stops are set forth in S5.1.4.3, which reads as follows: Each vehicle with a GVWR of 10,000 pounds or less shall be capable or making five recovery stops from 30 mph at 10 fpsps for each stop, with a control force application that falls within the following maximum and minimum limits: (1) A maximum for the first four recovery stops of 150 pounds, and for the fifth stop, of 20 pounds more than the average control force for the baseline check, and (2) A minimum of-- (A) The average control force for the baseline check minus 10 pounds, or (B) The average control force for the baseline check times 0.60, whichever is lower (but in no case lower than 5 pounds). . . . Thus, the minimum and (for one stop) the maximum control force limits for the recovery stops are calculated using the average control force for the baseline check stops or snubs. This average control force is the one calculated under S7.11.1.1 using the maximum control force of each of the baseline check stops or snubs. I hope this information is helpful. If you have any further questions about NHTSA's safety standards, please feel free to contact Marvin Shaw of my staff at this address or by telephone at (202) 366-2992. Sincerely, Paul Jackson Rice Chief Counsel"; |
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ID: aiam1956OpenMr. Samuel W. Alderson, President, Humanoid Systems, Division of Alderson Biotechnology Corporation, 5250 El Segundo Boulevard, Hawthorne, CA 90250; Mr. Samuel W. Alderson President Humanoid Systems Division of Alderson Biotechnology Corporation 5250 El Segundo Boulevard Hawthorne CA 90250; Dear Mr. Alderson: This is in response to your letter of May 30, 1975, to th Administrator.; Thank you for the offer to assist in the establishment of ne specifications for dummy skin and flesh components. Any procurement of such services would be awarded by competitive procurement, and I hope your company will participate in any such competition when solicited.; The NHTSA issued Part 572, in the form of a large number of dumm design and material specifications supplemented by some calibrating component tests, in order to specify the vehicle performance requirements of certain crash-test standards, such as Standard No. 203, as precisely and objectively as possible. Dummies are not regulated items and not ends in themselves, as S 572.3 states, the dummy specification 'does not in itself impose duties or liabilities on any person.' Thus, the dummy specification serves only as a means of informing the vehicle manufacturers how their vehicles must perform if and when tested by the government. There is no regulatory requirement either for 'certification' of dummies or their 'verification by an independent agency' or anyone else. It may be assumed that government testing will be carried out with dummies that conform to Part 572 as closely as possible. Vehicle manufacturers can ascertain that their vehicles will pass government tests by any means they choose. With this in view, it should be clear that any deviations from the Part 572 specifications are purely a matter of private negotiation and decisionmaking between the dummy manufacturers and their customers, and no governmental 'approvals' are possible or appropriate.; Any changes in Part 572 will of course be done through notice an opportunity for comment, and we expect and hope for your full participation in an administrative proceeding when it takes place.; Sincerely, Robert L. Carter, Associate Administrator, Motor Vehicl Programs; |
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ID: aiam0644OpenMr. Gorou Utsunomiya, Chief, Liaison Engineer, Toyo Kogyo Detroit Office, 3841 Mystic Valley Dr., Bloomfield Hills, Michigan 48013; Mr. Gorou Utsunomiya Chief Liaison Engineer Toyo Kogyo Detroit Office 3841 Mystic Valley Dr. Bloomfield Hills Michigan 48013; Dear Mr. Utsunomiya: This is in response to your letter of March 16, 1972, in which you as whether the definition of 'unloaded vehicle weight' is the same as or 'curb weight' plus optional parts, and whether the definition of 'gross vehicle weight' is the same as that for 'maximum loaded vehicle weight.'; The two sets of definitions are expressed in substantially differen terms. The new terms, 'unloaded vehicle weight' and 'gross vehicle weight rating' are more general than the older ones. The newer terms also eliminate some ambiguities in the definitions based on 'curb weight,' such as just what is meant by 'standard equipment,' and whether other vehicle fluids besides fuel, oil, and coolant should be included. Further, GVWR is a rating, not necessarily identical to any scale weight although some constraints have been placed on it in our Certification regulations (S567.4(g)(3)).; Thus although the two sets of definitions are somewhat similar in thei application, they are different enough that each must be interpreted and used in its own terms.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam2679OpenMr. Stephen C. Nimmer, Senior Supervising Engineer, Oshkosh Truck Corporation, Box 2566, Oshkosh, WI 54901; Mr. Stephen C. Nimmer Senior Supervising Engineer Oshkosh Truck Corporation Box 2566 Oshkosh WI 54901; Dear Mr. Nimmer: This is in reply to your letter of August 29, 1977, asking fo confirmation of your interpretation of S4.5.4 of Motor Vehicle Safety Standard No. 108.; Paragraph S4.5.4 requires that 'The stop lamps on each vehicle shall b activated upon application of the service brakes.' Oshkosh trucks are equipped with split air brake systems. This system incorporates a parking brake system on the rear axles. You indicated that there are three conditions under which the parking brakes will apply:>>>; Condition 1. - Parking Application. The spring brakes are driver applied through a hand operated parkin control.; Condition 2. - Rear Service Brake System Failure. The spring brakes can be driver applied through the service brake foo operated treadle valve control in the event of a failure in the rear service brake system.; Condition 3. - Spring Brake Cavity Pressure Loss. A component failure which allows air pressure to exhaust from th spring cavity of the rear brake chambers will cause the spring brakes (parking brakes) to apply. This condition is not driver initiated.'<<<; You have interpreted Condition 2 as the only 'services brake application since it is the only one of the three that is driver-initiated through the service brake control, and that stop lamp activation under the other two Conditions is not required by Standard No. 108.; This will confirm your interpretation. With respect to Condition 1, w do not consider that driver application of the parking brake portion of the service brake system is 'application of the service brakes' within the meaning of S4.5.4. Nor do we consider that activation of the parking brakes through component failure is 'application of the service brakes', your Condition 3.; Sincerely, Frank Berndt, Deputy Chief Counsel |
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ID: aiam5446OpenMr. Michael Winzkowski FABA Autoglas Produktion c/o Farmont Sunroofs, Ltd. 2346 Success Drive P.O. Box 981 Odessa, FL 33556-0981; Mr. Michael Winzkowski FABA Autoglas Produktion c/o Farmont Sunroofs Ltd. 2346 Success Drive P.O. Box 981 Odessa FL 33556-0981; "Dear Mr. Winzkowski: This responds to your letter about manufacturer's certification responsibilities under Federal Motor Vehicle Safety Standard No. 205, Glazing materials (49 CFR 571.205, copy enclosed). You state that you are a United States-based subsidiary of a German automotive sunroof manufacturer. You are having problems explaining to the German authorities the differences between the certification requirements of the two countries and request a letter explaining that the U.S. uses a self-certification procedure. I am pleased to provide this information. As you know, every item of glazing for use in motor vehicles that is sold in or imported into this country must be certified as complying with FMVSS No. 205. This standard sets forth both performance and labeling requirements that must be satisfied by the automotive glazing. In enforcing its safety standards, the National Highway Traffic Safety Administration (NHTSA), which is part of the U.S. Department of Transportation, does not follow the European practice of requiring the manufacturer of motor vehicle equipment to deliver an item of the equipment to specified institutes for testing before the product can be sold. Instead, as required by the U.S. Congress, the manufacturer 'self-certifies' that each of its items of motor vehicle equipment fully satisfies all requirements of the applicable Federal motor vehicle safety standards. Thus, each item of automotive glazing is self-certified by its manufacturer as complying with FMVSS No. 205. NHTSA does not require that the manufacturer's certification be based on a specified number of tests of the glazing or on any tests at all. Under the statute, the agency only requires that the certification be made with the exercise of 'due care' on the part of the manufacturer. It is up to the manufacturer to determine what data, test results, or other information is needed to enable it to certify that the glazing complies with Standard No. 205. We do recommend, however, that a manufacturer selling its glazing in the United States for the first time test those products, according to the test procedures specified in Standard No. 205. Once the manufacturer has determined that its glazing complies with the requirements of Standard No. 205, it certifies that compliance by marking the glazing with the symbol DOT, as specified in section S6 of Standard No. 205. You specifically asked for verification that 'no US DOT testing or certification is conducted when DOT numbers are assigned to manufacturers.' The 'DOT number' to which you refer is the manufacturer's code mark that is assigned by NHTSA on request of the glazing manufacturer (S6.2 of FMVSS No. 205). Your understanding is correct. NHTSA does not test glazing products or review manufacturers' compliance data prior to or as a condition for assigning a manufacturer's code mark pursuant to S6.2 of Standard No. 205. I hope you find this information helpful. If you have any other questions, please contact Mr. Marvin Shaw of my staff at (202) 366-2992. Sincerely, John Womack Acting Chief Counsel Enclosure"; |
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ID: aiam2383OpenMr. Richard J. Brandewie, Program Manager, B.F. Goodrich Engineered Systems Company, P.O. Box 340, Troy, OH 45373; Mr. Richard J. Brandewie Program Manager B.F. Goodrich Engineered Systems Company P.O. Box 340 Troy OH 45373; Dear Mr. Brandewie: This responds to your July 26, 1976, question whether the 'no lockup requirement of S5.3.1 and S5.3.2 of Standard No. 121, *Air Brake Systems*, requires wheel sensors on both axles of a tandem axle system in those cases where the 'no lockup' performance is provided by means of an antilock system. I have enclosed a detailed discussion of this issue that responded to a similar question from another manufacturer. The response should answer your question.; Yours truly, Frank Berndt, Acting Chief Counsel |
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ID: aiam0214OpenMr. C. J. Newman, Director of Engineering, The Grote Manufacturing Company, State Route 7, P. O. Box 766 N. M. S., Madison, IN 47250; Mr. C. J. Newman Director of Engineering The Grote Manufacturing Company State Route 7 P. O. Box 766 N. M. S. Madison IN 47250; Dear Mr. Newman: Thank you for your letter of February 19, 1970, to Mr. Julian E Leysath of this Office asking for suggestions on lighting equipment for a trailer manufactured by Toter, Inc.; This will confirm your understanding that the Toter is considered trailer under the Federal Motor Vehicle Safety Standards, and not a dolly. Since the manufacturer is responsible for compliance with Federal Standard No. 108 (Lamps, Reflective Devices, and Associated Equipment) I am unable to provide specific suggestions or recommendations for lighting the vehicle in question.; Sincerely, Rodolfo A. Diaz, Acting Director, Motor Vehicle Safet Performance Service; |
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ID: aiam2229OpenMrs. Anderson, Inertia Switch, Ltd., Hardings Lane, Hartley Wintney, Hampshire, England RG278QA; Mrs. Anderson Inertia Switch Ltd. Hardings Lane Hartley Wintney Hampshire England RG278QA; Dear Mrs. Anderson: I am writing in response to your March 9, 1976, telephone conversatio with Mark Schwimmer of this office concerning the meaning of 'GVWR' as it appears in Federal Motor Vehicle Safety Standard No. 301-75, *Fuel System Integrity*.; 'GVWR' or 'Gross vehicle weight rating' is defined in 49 CFR 571.3 as: >>>the value specified by the manufacturer as the loaded weight of single vehicle.<<<; One constraint on this specification is found in S567.4(g)(3) of 49 CF Part 567, *Certification*, which requires that the GVWR shall not; >>>be less than the sum of the unloaded vehicle weight, rated carg load, and 150 pounds times the vehicle's designated seating capacity... .<<<; An information sheet entitled 'Where to Obtain Federal Motor Vehicl Safety Standards and Regulations' is enclosed for your convenience. If you have any further questions, please do not hesitate to write.; Yours truly, 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.