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 |
|---|---|
ID: nht94-2.89OpenTYPE: INTERPRETATION-NHTSA DATE: May 16, 1994 FROM: John A. Griffiths TITLE: None ATTACHMT: Attached To Letter Dated 6/3/94 From John Womack To John Griffiths (A42; Std. 102) TEXT: Dear Sir, I should be pleased if you would inform me whether or not motor vehicles post 1990 are required by law to have a [Illegible Word] safety switch so that the vehicles cannot be started in gear if they have automatic or manual transmissions. Thankfully yours, (804) 874-8039 DRN spoke to Mr. Griffiths on 5/26. Mr. Griffiths essentially wanted to know whether, on a manual transmission vehicle, there must be a neutral safety switch, i.e., making it impossible to start the vehicle unless the clutch is fully depressed. as the o wner of a MY93 Dodge, with a manual transmission, he was concerned about this. |
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ID: nht71-4.18OpenDATE: 10/06/71 FROM: AUTHOR UNAVAILABLE; C. A. Baker for E. T. Driver; NHTSA TO: Strick Corporation TITLE: FMVSS INTERPRETATION TEXT: This is in reply to your letter of September 21, 1971, to Mr. Douglas Toms, Administrator, National Highway Traffic Safety Administration, requesting an interpretation on the mounting of Identification lamps on your trailers. We hesitate to agree with you that it is not practicable to mount the Identification lamps at the extreme height of the trailer. It would appear to be practicable to mount these lamps at the extreme height, even if a shield were necessary to prevent damage to the lamps during use. If the identification lamps are mounted at the extreme height of the trailer, the clearance lamp mounting height is optional; therefore, clearance lamps could be mounted on the rear crossmember, as shown on your drawing SK-24139. |
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ID: 0133Open Mr. Rick Rogers Dear Mr. Davis: Robert Hellmuth of this agency has sent us for reply your letter of June 8, 1994, commenting that "a car's brake lights should go on not only when the brake pedal is pressed, but should also go on when the gas pedal is released." The enclosed copy of a letter dated January 25, 1990, to Larry Snowhite, Esq., represents the agency's views on this matter, now as then. We appreciate the concern for safety that prompted you to get in touch with us. Sincerely,
John Womack Acting Chief Counsel Enclosure ref:108 d:7/21/94
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1994 |
ID: 12159.mlsOpen Mr. G.T. Bowman Dear Mr. Bowman: This responds to your request for the National Highway Traffic Safety Administration (NHTSA) to reconsider a previous interpretation of the dynamometer test procedures set forth in S5.4.2.2 of Standard No. 121. The purpose of these requirements is to help ensure that brakes retain adequate stopping capability during and after exposure to prolonged or severe use, such as long, downhill driving. In a June 29, 1995, interpretation to Advance Engineered Products, Mr. John Womack, the Acting Chief Counsel, stated that "the same limitation on the pressure which can be used to achieve the deceleration rate specified in S5.4.2.1 applies to the deceleration in S5.4.2.2." In support of your request for the agency to reconsider its interpretation, you reference the March 1, 1976 final rule which states that The "hot stop"deletion was also supported, though most comments on the proposal stated that the whole section should be deleted and not simply the last sentence. The NHTSA purposely did not delete the whole section, so that the sequence of testing would remain as in the past, to preserve the data on recovery that was developed following "hot stop" testing. Therefore the required test level is deleted as proposed, but the testing remains in the standard to maintain the same sequence as in the past. (41 FR 8733, 8787) Amendatory language in the final rule states that "Section S4.2.2 is amended by deletion of the last sentence of the text." As a result, that provision reads as follows: One minute after the end of the last deceleration required by S5.4.2.1 and with the drum or disc rotating at a speed of 20 m.p.h., decelerate to a stop at an average deceleration rate of 14 f.p.s.p.s. The service brake line air pressure shall not exceed 108 p.s.i. In the proposal leading to the March 1976 final rule, NHTSA had stated that "For all vehicles, the dynamometer brake power and recovery requirements would be modified by increasing the upper pressure limit. The 'hot stop' dynamometer requirement (S5.4.2.2) would be deleted, since the 14 fpsps deceleration rate is not comparable to the new stopping distance requirements. (40 FR 59222, December 22, 1975) Based on these prior agency statements, I have decided to modify NHTSA's June 1995 interpretation. Upon further reflection, Standard No. 121 does not specify any limitation on the pressure that can be used to achieve the required deceleration rate specified in S5.4.2.2. I hope this information is helpful. If you have any further questions about NHTSA's safety standards, please feel free to contact Marvin Shaw at this address or by telephone at (202) 366-2992. Sincerely, Samuel J. Dubbin Chief Counsel ref:121 d:7/29/96 |
1996 |
ID: 2830oOpen AIR MAIL Mr. Mamoru Arisaka Manager, Automotive Lighting Homologation Sect. Stanley Electric Co., Ltd. 2-9-13, Nakameguro, Meguro-ku Tokyo 153, JAPAN Dear Mr. Arisaka: This is in reply to your letter of July 7, 1988, with respect to a motorcycle lighting device called the "rolling headlamp." The headlamp is designed to have its vertical plane always perpendicular to the ground regardless of the inclination of the motorcycle. You have asked whether such a device is legally permissible. Motor Vehicle Safety Standard No. l08 does not prohibit alteration of the mounting angle of a headlamp. Although paragraph S4.3.1 requires each lamp to "be securely mounted on a rigid part of the vehicle," your lamp appears to be "securely mounted" even if it is able to rotate. I hope this answers your question. Sincerely,
Erika Z. Jones Chief Counsel /Ref:108 d:8/26/88 |
1988 |
ID: nht94-3.79OpenTYPE: INTERPRETATION-NHTSA DATE: July 21, 1994 FROM: John Womack -- Acting Chief Counsel, NHTSA TO: Rick Rogers TITLE: None ATTACHMT: Attached to letter dated 6/8/94 from Rick Rogers to Robert Hellmuth (OCC-10133) abd letter dated 1/25/90 from Stephen P. Wood to Larry S. Snowhite TEXT: Robert Hellmuth of this agency has sent us for reply your letter of June 8, 1994, commenting that "a car's brake lights should go on not only when the brake pedal is pressed, but should also go on when the gas pedal is released." The enclosed copy of a letter dated January 25, 1990, to Larry Snowhite, Esq., represents the agency's views on this matter, now as then. We appreciate the concern for safety that prompted you to get in touch with us. Enclosure |
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ID: nht94-5.32OpenDATE: May 16, 1994 FROM: John A. Griffiths TITLE: None ATTACHMT: Attached To Letter Dated 6/3/94 From John Womack To John Griffiths (A42; Std. 102) TEXT: Dear Sir, I should be pleased if you would inform me whether or not motor vehicles post 1990 are required by law to have a [Illegible Word] safety switch so that the vehicles cannot be started in gear if they have automatic or manual transmissions. Thankfully yours, (804) 874-8039 DRN spoke to Mr. Griffiths on 5/26. Mr. Griffiths essentially wanted to know whether, on a manual transmission vehicle, there must be a neutral safety switch, i.e., making it impossible to start the vehicle unless the clutch is fully depressed. as the owner of a MY93 Dodge, with a manual transmission, he was concerned about this. |
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ID: 1984-4.14OpenTYPE: INTERPRETATION-NHTSA DATE: 12/21/84 FROM: AUTHOR UNAVAILABLE; Frank Berndt; NHTSA TO: J.W. Hughes -- Vice President, The Kansas City Southern Railway Company TITLE: FMVSS INTERPRETATION TEXT: Mr. J. W. Hughes Vice President - Executive The Kansas City Southern Railway Company 114 W. Eleventh St. Kansas City, MO 64185 Your letter of November 7, l984, does not note the dates of previous correspondence with us, and we are unable to find copies of what we recall as at least two letters from this office to the Railway or its representative on the Mercedes Zwei Weg rail conversion. However, it is our recollection that because the van uses the public roads from one rail inspection site to another it is a "motor vehicle" for purposes of compliance with the Federal motor vehicle safety standards, and that this interpretation has been previously furnished the Railway. Your letter contains no new facts that warrant a reconsideration of our earlier interpretations. Sincerely, Frank Berndt, Chief Counsel |
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ID: nht68-3.32OpenDATE: 05/02/68 FROM: AUTHOR UNAVAILABLE; Robert M. O'Mahoney; NHTSA TO: Weslock Company TITLE: FMVSS INTERPRETATION TEXT: Your letter of April 22, 1968, to Mr. Bridwell has been referred to me for reply. You state that it is your understanding that the proposed rule making in Docket 2-16 will require door locks on trailers and mobile homes to be so constructed "as to be recessed flush on exterior doors." Federal motor vehicle safety standard No. 206, Door Latches, Hinges, and Locks - Passenger Cars, was originally issued on January 31, 1967 and became effective on January 1, 1968. An amendment to this standard was issued on April 24, 1968 with an effective date of January 1, 1969. Neither the standard as presently written or the proposed amendment in Docket 2-16 is applicable to trailers and mobile homes. Moreover, there is no provision either in the standard or in the proposed amendment which requires that door locks must be so constructed "as to be recessed flush on exterior doors," even as to those motor vehicles to which the standard applies presently or to which it is proposed to apply in Docket 2-16. For your information, we are enclosing a copy of the recent amendment to Standard No. 206 as attachment No. 1, and a copy of the proposed amendment for Docket 2-16 as attachment No. 2. In view of the foregoing, you may wish to reconsider your request that we forward to you the comments contained in Docket 2-16. The cost to you for forwarding those comments would be fifty cents a page and the number of pages contained in Docket 2-16 is considerable. Since your understanding of the thrust of Docket 2-16 is not correct, your request for an extension of time to May 25, 1968 is denied. WESLOCK COMPANY April 22, 1968 Federal Highway Administration Room 316, Donohoe Building 6th & D Street, S. W. Washington, D. C. 20591 Attention: Lowell K. Bridwell Federal Highway Administrator Although we have not received Docket 2-16, an amendment to Standard 206, we are told that all interested persons have until April 25, 1968 to file comments. As manufacturers of locks for trailers and mobile homes, we have reason to believe we are affected by Docket 2-16. By hearsay, we understand that this Docket will require that locks be so constructed as to be recessed flush on exterior doors. If our understanding is correct, we fear that we, and many other lock manufacturers, may be seriously damaged by this requirement. We respectfully request an extension of time until May 25, 1968 to file comments and shall appreciate your sending us Docket 2-16 for study. May we also suggest that serious consideration be given to the danger of entrapment in trailers arising from the use of locks which do not open automatically upon turning of the inside knob. To prevent loss of life, it may be wise to require panic-proof locks; that is, those which unlock and open merely by turning the inside knob and which do not depend upon the performance of some precedent operation. Sincerely, Ernest Cipriano President |
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ID: nht74-2.37OpenDATE: APRIL 26, 1974 FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA TO: Granning Suspensions Inc. TITLE: FMVSR INTERPRETATION TEXT: This responds to your March 21, 1974, request for an explanation of your certification responsibilities under the National Traffic and Motor Vehicle Safety Act of 1966 as a manufacturer of liftable and "additional" axles which are installed on completed vehicles by an independent truck equipment dealer or, in some cases, by the vehicle manufacturer at the factory. Your responsibilities under Standard 121, Air brake systems, are largely the same as your responsibility for certification of the GAWR of an axle under 49 CFR Part 567, although somewhat more complicated. It is the responsibility of the vehicle manufacturer to certify compliance with Standard 121 (49 CFR Part 567.4), and if the completed vehicle is altered, it is the responsibility of the vehicle alterer (49 CFR Part 567.7). The addition of an axle will change the GAWR-GVWR and the brake performance of the altered vehicle and will require recertification by the dealer who undertakes alteration. A dealer is normally not equipped to recertify an altered vehicle, except on the basis of certification information supplied to him by the manufacturer of the component that is being added. A component manufacturer like yourself might issue a performance guaranty which relies on the information that is supplied to him by the manufacturer of the basic parts (e.g. brakes, axles in your case) and which is conditioned on the observance of certain limits on installation. For instance, the reservoir volume requirement (S5.1.2.1) might be exceeded if the liftable axle manufacturer did not qualify his information by stating that a certain tank volume must be provided to serve the air chambers on his axle system. Another qualification could refer to brake actuation and release time as complying only if it did not reduce the brake actuation and release timing of the vehicle as a whole. The effect of your axle on each of the requirements would have to be determined. We do not require certification of the axle by you as its manufacturer. |
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.