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: aiam0887OpenMr. Kenneth D. Uding, Sales Promotion, Stimsonite Division, Amerace-Esna Corp., 3445 North Kimball Avenue, Chicago, Illinois 60618; Mr. Kenneth D. Uding Sales Promotion Stimsonite Division Amerace-Esna Corp. 3445 North Kimball Avenue Chicago Illinois 60618; Dear Mr. Uding: This is in response to your request for an interpretation of Standar 125, Warning Devices, with respect to the required marking of the date of manufacture on the device. I apologize for the delay in answering your letter. You inquire whether a circular marking in which the last numeral of the year of manufacture is printed inside an inner circle and the month of manufacture is represented by 'small dots' in an outer circle meets the requirements of S5.1.4.; S5.1.4 requires the device to be 'permanently and legibly marked wit ... month and year of manufacture, which may be expressed numerically, as '6/72' ...' The intent of this provision is not only to 'identify subquality batches' to the manufacturer or enforcement personnel, but also to provide the consumer with a clear indication of the date of manufacture in case of a possible defect or failure to meet safety standards. The method of marking the date of manufacture which you propose would not satisfy the language or intent of the requirement, since its meaning would not be clear to the average consumer.; Sincerely, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam2322OpenMr. K. Nakajima, Director/General Manager, Factory Representative Office, Toyota Motor Sales, U.S.A., Inc., 1099 Wall Street, West Lyndhurst, New Jersey 07071; Mr. K. Nakajima Director/General Manager Factory Representative Office Toyota Motor Sales U.S.A. Inc. 1099 Wall Street West Lyndhurst New Jersey 07071; Dear Mr. Nakajima: This is in response to your February 23, 1976, letter concerning th rim marking requirements of S5.2 of Federal Motor Vehicle Safety Standard No. 120, *Tire Selection and Rims for Motor Vehicles Other Than Passenger Cars*.; In its present form, S5.2 requires a rim to which the standard applie to be marked with its size designation and, if it is a multi-piece rim, its type designation as well. There is no prohibition on the marking of additional information beyond that which is required. Therefore, the marking of single piece rims with a type designation is permitted.; Please note that, in a notice published on Mary 6, 1976 (41 FR 18659 Docket No. 71-19, Notice 4), the National Highway Traffic Safety Administration delayed the effective dates of several of the standard's requirements. In particular, the effective date of S5.2, *Rim Marking*, was delayed until August 1, 1977. A copy of this notice is enclosed for your convenience.; Yours truly, Stephen P. Wood, Assistant Chief Counsel |
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ID: aiam1359OpenMr. David E. Martin, Manager, General Motors Corporation, Automotive Safety Engineering, Warren, MI 48090; Mr. David E. Martin Manager General Motors Corporation Automotive Safety Engineering Warren MI 48090; Dear Mr. Martin: This is in reply to your letter of December 3, 1973, requestin clarification of paragraph S5.1(c) of Motor Vehicle Safety Standard No. 217, Bus Window Retention and Release.' Your letter, and attached photograph of a push-out window, suggest that the words window frame' in S5.1(c) refer not to the window sash', the structure immediately surrounding the glazing material, but to the side of the bus.; We do not agree. The words window frame' in S5.1(c), with respect t the push out window, refer to the component that interfaces with the glazing.; The intent of S5.1 is to require a window retention system to be stron enough to retain occupants in a crash, at least up to the strength limit of the glazing itself. Since there are no limits on the movement of the window sash' relative to the bus structure, the interpretation you suggest would allow a window system that provides no retentive properties at all, thus defeating one of the main purposes of the standard.; Sincerely, Lawrence R. schneider, Chief Counsel |
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ID: aiam0647OpenMr. Vincent G. Grey, Engineering Manager, Truck Trailer Manufacturers Association, 1413 K Street, N.W., Washington, DC 20005; Mr. Vincent G. Grey Engineering Manager Truck Trailer Manufacturers Association 1413 K Street N.W. Washington DC 20005; Dear Mr. Grey: This is in reply to your letter of March 16, 1972, forwarding to us draft of a TTMA Recommended Practice concerning GAWR and GVWR that you have developed as a guide for the truck trailer industry. You ask whether the draft is consistent with the applicable regulations (49 CFR Parts 567, 568).; The draft which you submitted is consistent with the regulation although it is much more specific than the regulations and represents just one method of achieving compliance. We appreciate your efforts in making the substance of the regulations available to this large segment of the industry.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam5639OpenMr. Larry W. Strawhorn Vice President of Engineering American Trucking Associations 2200 Mill Road Alexandria, VA 22314-4677; Mr. Larry W. Strawhorn Vice President of Engineering American Trucking Associations 2200 Mill Road Alexandria VA 22314-4677; "Dear Mr. Strawhorn: This letter responds to your request for a interpretation of the antilock power circuit requirements set forth at S5.1.6.3 of Standard No. 121, Air Brake Systems. This provision states that S5.1.6.3 Antilock Power Circuit for Towed Vehicles. Each truck tractor manufactured on or after March 1, 1997 and each single unit vehicle manufactured on or after March 1, 1998 that is equipped to tow another air-braked vehicle shall be equipped with one or more separate electrical circuits, specifically provided to power the antilock system on the towed vehicle(s). Such a circuit shall be adequate to enable the antilock system on each towed vehicle to be fully operable. (Emphasis added.) You believe that the phrase 'separate electrical circuit' allows for the continued use of the single SAE J560 connector if one of the seven pins provides full-time power for the ABS. You further believe that the ABS malfunction signal can be multiplexed on any circuit of the connector and that the other trailer devices can be powered off the circuit as long as the circuit is adequate to enable the antilock system on each towed vehicle to be fully operable. In the March 10, 1995 final rule, NHTSA decided to adopt the proposed full-time power requirement for trailer ABSs. (60 FR 13216) The agency explained that it amended the standard's wording to clarify that towing vehicles must have a corresponding separate circuit specifically provided to power the antilock system on the towed vehicle or vehicles. The agency stated that requiring a separate circuit 'will ensure the strongest possible source of electrical power from the tractor to ensure the functioning of all the ECUs and modulators that are employed in the antilock brake system, or systems, on single trailers, or multiple trailers and converter dollies in multi-trailer combinations. It also stated that this requirement will ensure a continuous malfunction indication whenever a malfunction exists. The agency further stated that it has left the decision about which type of connector should be used to the industry. In response to your question about the use of one of the pins in the seven-pin connector to provide full-time power for the ABS, the use of such a pin would be permissible provided that the pin services a 'separate' electrical circuit to 'specifically provide' full time power for the trailers in combination vehicles. This means that the circuit's sole function must be to provide ABS powering, i.e., other trailer devices may not be powered off this separate electrical circuit. This would preclude the use of the pin to power the ABS malfunction signal. Since the requirement for the ABS malfunction circuit did not specify that the circuit used for transmitting the malfunction signal be a 'separate' one, ABS malfunction signals can be multiplexed on other circuits with pins in the electrical connector, but not on the circuit and pins used to power the ABS system. It is important to note that the ABS semitrailer fleet study report (DOT HS 808 059) concluded that the voltages delivered by powering system approaches that employed dedicated separate circuits (i.e., the Cole Hersee, ISO, and 6-pin auxiliary systems) were well within the required limits for ECU powering, whereas, the voltages delivered through the stoplamp circuit did not perform as well. The agency concluded that these data indicate the superiority of a separate circuit powering of the trailer ABS and therefore, justify the separate circuit requirement. As you are aware, NHTSA received several petitions for reconsideration about the separate electrical circuit. The agency anticipates that the final rule in response to these petitions for reconsideration will have a detailed discussion of these requirements. In addition, the agency may decide to modify these requirements. I hope this information has been helpful. If you have any other questions, please contact Marvin Shaw of my staff at this address or by phone at (202) 366-2992. Sincerely, Samuel J. Dubbin Chief Counsel"; |
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ID: aiam0584OpenMr. John F. Waldherr, Director of Engineering, Wells Manufacturing Corp., Fond Du Lac, WI 54935; Mr. John F. Waldherr Director of Engineering Wells Manufacturing Corp. Fond Du Lac WI 54935; Dear Mr. Waldherr: In your letter of February 2 you refer to paragraph S4.5.1 of Moto Vehicle Safety Standard No. 108 and its reference to SAE Recommended Practice J564a, *Headlamp Beam Switching*, April 1964. You ask 'whether there is anything in your Docket related to Rule No. 108 to bring it up to either J564b or J564c.'; Perhaps you misread S4.5.1, but it does allow conformance with J564b a an alternative to J564a. No proposal has been issued requiring or allowing conformance with J564c.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam1305OpenMr. Kurt Meier, Porsche, Research and Development, 8124 Billow Vista Drive, Playa Del Rey, CA 90291; Mr. Kurt Meier Porsche Research and Development 8124 Billow Vista Drive Playa Del Rey CA 90291; Dear Mr. Meier: Thank you for your letter of September 2, 1973, to Mr. Jame Hofferberth of my staff, inquiring if a particular safety belt system which is illustrated in your enclosures meets the criteria for a passive restraint system.; The interpretation of a passive restraint system published in th Federal Register on May 4, 1971 (36 F.R. 8296) was:; >>>'The concept of an occupant protection system that requires 'n action by vehicle occupants' as used in Standard No. 208 is intended to designate a system that requires no action other than would be required if the protective system were not present in the vehicle.'<<<; With respect to your belt system, a requirement for placing the belt i the storage holder when leaving the car would be considered 'action' and not permitted under the above interpretation of a passive system. However, if the belt system could be entered and exited with essentially no action, in the event the storage holder was not used, automatically releasing 'convenience' holder would not compromise the belt's qualification as a passive system.; Sincerely, Robert L. Carter, Associate Administrator, Motor Vehicl Programs; |
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ID: aiam2189OpenMr. Lewis Coffey, Chief Engineer, Gillig Brothers School Bus Co., 25800 Clawinter Rd., Hayward, CA 94540; Mr. Lewis Coffey Chief Engineer Gillig Brothers School Bus Co. 25800 Clawinter Rd. Hayward CA 94540; Dear Mr. Coffey: This is in response to your request for information concerning method of ensuring the compliance of school buses with the barrier crash test requirements of Federal Motor Vehicle Safety Standard No. 301-75, *Fuel System Integrity*.; Standard No. 301-75, while establishing minimum performance levels does not specify any particular design requirements for school bus fuel systems. A manufacturer is free to design his vehicles in the manner that he believes most appropriate to ensure compliance. To this end, you may find helpful information in a study by Dynamic Science entitled *School Bus Safety Improvement Program*. The NHTSA cannot assure you, however, that following the suggestions contained in the study will guarantee that your school buses will comply with the standard.; The study is filed in the NHTSA's public docket as document numbe 75-03-GR1. Copies may be obtained by writing to:>>>Technical Reference Branch, National Highway Traffic Safety Administration, Room 5108, 400 Seventh Street, S.W., Washington D.C. 20590<<<; You should refer to the following publication numbers: HS 801-615 -616, and -617.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam1237OpenMr. Wesley Wells, 6879 Sayler Avenue, Cincinnati, OH 45233; Mr. Wesley Wells 6879 Sayler Avenue Cincinnati OH 45233; Dear Mr. Wells: This is in response to your letter of May 10, 1973, concerning you purchase of a 1973 truck from Haag Motors which was sold as new but had an odometer reading of 1,125 miles at the time of sale. I apologize for our delay in replying.; The sale of a vehicle as new with an odometer reading of 1,125 mile does not violate Federal law, although it may violate a consumer protection statute in your state or the state of purchase. There is, however, a Federal law which requires sellers of motor vehicles to make an odometer disclosure statement at the time of sale. If you purchased the truck after March 1, 1973, and its gross vehicle weight rating does not exceed 16,000 pounds, you may have a private civil action against the dealer for $1,500 or treble damages, if he failed to execute the written statement.; You may wish to consult an attorney with regards to your rights in thi matter. A copy of the Act and implementing regulations are enclosed for your information.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam0293OpenMr. Y. Takami, Engineer, Toyo Tire (U.S.A.) Corporation, 3136 East Victoria Street, Compton, CA 90221; Mr. Y. Takami Engineer Toyo Tire (U.S.A.) Corporation 3136 East Victoria Street Compton CA 90221; Dear Mr. Takami: This is in reply to your letter of February 2, 1971, to Mr. Casanov concerning Part 574 - Tire Identification and Record Keeping.; Adding a group of numbers consisting of three-digits to the tir identification number is not permitted under the regulation because the additional numbers would be too easily confused with the tire identification number.; You are not prohibited, however, from placing the additiona three-digit number elsewhere on the tire in an area where it would not be confused with the required tire identification number. Anywhere further than six inches would be far enough to avoid confusion.; Sincerely, Lawrence R. Schneider, 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.