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 |
|---|---|
| search results table | |
ID: aiam2113OpenMr. Lee, Tong Shin Chemical Products Co., Ltd., 325 - 12th Street, Palisades Park, New Jersey 07650; Mr. Lee Tong Shin Chemical Products Co. Ltd. 325 - 12th Street Palisades Park New Jersey 07650; Dear Mr. Lee: This is in response to your inquiry concerning the addition of th symbol 'DOT' to tires imported into this country, and in confirmation of your telephone conversation with Mr. Schwartz of this office.; 49 CFR Part 574, Tire Identification and Recordkeeping, requires tir manufacturers to permanently mold into or onto the sidewall of tires an identification number and the symbol DOT. The position of the identification number and DOT symbol is illustrated in Figures 1 and 2 of the Regulation. The symbol DOT, as stated in Motor Vehicle Safety Standard No. 109, New Pneumatic tires, 49 CFR 571.109, constitutes a certification that the tire conforms to all applicable safety standards.; Neither Standard No. 109 nor Part 574 prohibit the branding of th symbol DOT onto the tire after manufacture, as long as the information becomes part of the actual sidewall material. By branding the symbol DOT onto the tire you are certifying that the tires meet all the requirements of the motor vehicle safety standards based on information which, in the exercise of due care, you know to be accurate.; If you have further questions concerning this matter, please do no hesitate to contact me.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
|
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"; |
|
ID: aiam2406OpenMr. Kenneth C. Ploeger, President, ACUTEK, 5th & Dryden, Odessa, MO, 64076; Mr. Kenneth C. Ploeger President ACUTEK 5th & Dryden Odessa MO 64076; Dear Mr. Ploeger: This is in reply to your letter of October 13, 1976, to Mr. Lewis C Owen, Safety Standards Engineer, concerning an interpretation of the words 'optically combined' as they apply to your Acutek 301 combination rear lamp.; In the Acutek lamp, the data you submitted indicate that when th taillamp bulb is activated independently from the clearance lamp bulb, and vice versa, there is no appreciable amount of incidental light emitted from the lens of the clearance lamp. The amount of light 'spill' appears to be so small that it would not be interpreted (by a driver following the vehicle on which it is installed) as illuminating the lens of the taillamp when operated in the clearance lamp mode, and vice versa.; Accordingly, the Acutek 301 combination rear lamp appears to meet th requirements of Federal Motor Vehicle Safety Standard No. 108, 'Lamps, Reflective Devices, and Associated Equipment.'; Sincerely, E. T. Driver, Director, Office of Crash Avoidance, Moto Vehicle Programs; |
|
ID: aiam0591OpenMr. Jerry Warner, Manager, Foam Sales & Engineering, Keyston Brothers, 1000 Brannan Street, San Francisco, CA, 94103; Mr. Jerry Warner Manager Foam Sales & Engineering Keyston Brothers 1000 Brannan Street San Francisco CA 94103; Dear Mr. Warner: This is in reply to your letter of February 9, 1972, concerning th application of Motor Vehicle Safety Standard No. 302, 'Flammability of Interior Materials,' to an interior upholstered panel that you manufacture. You state that the panel is made up of a vinyl surface, a self-extinguishing foam, and a backing, and that the three materials must be tested as a single unit, or separately.; Paragraph S4.2 of Standard No. 302 specifies as follows:>>>S4.2 Th portions of the components that shall meet the requirements of S4.3 are all of the following:; (a) The surface material taken separately if it is not bonded, sewed o mechanically attached to underlying material.; (b) A composite consisting of the surface material bonded, sewed o mechanically attached to underlying material, if such a composite is used in the component.; (c) Padding and cushioning materials taken separately, if thos materials are not bonded, sewed or mechanically attached to surface materials.<<<; Under the language of S4.2, your surface material, and the underlyin foam should be tested as a composite pursuant to subparagraph (b). If the backing is considered a padding or cushioning material, it should be tested separately pursuant to subparagraph (c).; A notice of proposed rulemaking which would amend paragraph S4.2 wa published May 26, 1971 (36 F.R. 9565), and a copy is enclosed for your information. We expect that a final rule based on this proposal will be published in the near future. Under the wording of the proposal your material would be tested under subparagraph (b) to a depth of 1/2 inch, and padding and cushioning material would be tested again under subparagraph (c).; We are pleased to be of assistance. Yours truly, Richard B. Dyson, Assistant Chief Counsel |
|
ID: aiam5269OpenMr. Donald W. Vierimaa Vice President-Engineering Truck Trailer Manufacturers Association 1020 Princess Street Alexandria, VA 22314; Mr. Donald W. Vierimaa Vice President-Engineering Truck Trailer Manufacturers Association 1020 Princess Street Alexandria VA 22314; Dear Mr. Vierimaa: This responds to your letter of October 19, 1993 with respect to the trailer conspicuity requirements of Standard No. 108. You report that ' o ften a new tank trailer will be sold to a customer who will contract with another party to have a lining installed in the tank.' Because of the high heat used in the installation of the lining, retroreflective sheeting cannot be applied before the lining is installed. We believe that the trailer manufacturer is a more appropriate person for ensuring that its product meets the conspicuity requirements of Standard No. 108 than the installer of the lining, or the owner of the trailer. We would like to suggest alternative methods of compliance, other than a direct application of retroreflective tape to the trailer sides, as a resolution of this problem. Standard No. 108 permits the use of reflex reflectors as an alternative to retroreflective sheeting. If the trailer manufacturer prefers retroreflective sheeting, the sheeting may be applied at a lower level if deemed 'practicable', or it may be applied to horizontal strips of aluminum that can be fastened to the sides of tank trailers and removed during the installation of the lining. You also state that 'non-tank trailers may be sold without conspicuity treatment when the owner wishes to contract the application of special paint and logo schemes.' Sale of a trailer under these circumstances, without its compliance with the conspicuity requirements of Standard No. 108, would be an apparent violation of the National Traffic and Motor Vehicle Safety Act. Sincerely, John Womack Acting Chief Counsel; |
|
ID: aiam2056OpenMr. Ben Perchik, 1520 Dawn Drive, Louisville, Kentucky 40216; Mr. Ben Perchik 1520 Dawn Drive Louisville Kentucky 40216; Dera(sic) Mr. Perchik: #This is in response to your letter of July 29 1975, concerning tire identification markings, received by this agency on August 29, 1975. #I have attached two diagrams that illustrate the meaning of the tire code markings on new and retreaded tires. Immediately following 'DOT' is a two- or three-letter code (marked in red on the diagram) that indicates the manufacturer or retreader of the tire. I have also attached a list of the tire manufacturers and retreaders using each code. Following the manufacturer's code are two numbers representing the tire size (marked in blue on the diagram). Next, some tires will have three letters or numbers which represent an optional tire type code mainly of use to the manufacturer (marked in yellow on the diagram). The last three numbers represent the date of manufacture (marked in green on the diagram). #I hope this information proved useful to you. #Yours truly, Richard B. Dyson, Assistant Chief Counsel; |
|
ID: aiam4881OpenMr. Stephen Mamakas AIR Inc. 1517 West 9 Street Brooklyn, NY 11204; Mr. Stephen Mamakas AIR Inc. 1517 West 9 Street Brooklyn NY 11204; Dear Mr. Mamakas: In a telephone conversation with Stephen Kratzke o my staff, you asked for a clarification of my May 13, 1991 letter to you. My May 13 letter explained that Federal law would not affect any plans to repair air bags, but that a host of safety concerns and potential product liability issues under State law would arise in connection with any planned operation to repair air bags. You explained in your telephone conversation with Mr. Kratzke that the last paragraph of my May 13 letter to you suggests that I did not fully understand your company's plans. In that last paragraph, I referred to repacking a deployed air bag. In your telephone conversation, you explained that your company would not reuse any used equipment. Instead, you plan on installing the new air bags and new sensors recommended by the vehicle manufacturer. After your company completes its work on the vehicle, you are prepared to certify that the air bag will work as intended by the vehicle manufacturer. You asked how this difference would change the answer in my May 13 letter. This new information would not affect my previous advice that Federal law does not affect your planned repair operations. However, the safety concerns I expressed in my previous letter would be addressed if your company's repairs used only the replacement parts for the air bag system recommended by the vehicle manufacturer and installed those parts in accordance with the vehicle manufacturer's instructions. Sincerely, Paul Jackson Rice Chief Counsel; |
|
ID: aiam0284OpenMr. William R. Graham, Bus and Truck Supply Co., 315 Continental Avenue, Dallas, TX 75207; Mr. William R. Graham Bus and Truck Supply Co. 315 Continental Avenue Dallas TX 75207; Dear Mr. Graham: This is in reply to your letter of December 30, 1970, requesting a interpretation of Motor Vehicle Safety Standard No. 205, 'Glazing Materials,' as it applies to the forward-facing window above the windshield of a particular bus, a picture of which you enclosed.; Because the window in question is a forward-facing window, we canno conclude that it is an 'opening in the roof' under the standard. We apologize for the inconvenience caused by any implication to the contrary that you may have been given on your visit here.; Based upon the picture submitted, and your statement that the windo 'is not adjacent to passenger seating,' we conclude that this location is one that is not specifically designated by the standard. As such, the use of AS2 glazing, which you indicated you plan to use, or alternatively AS1, AS3, AS10, or AS11 glazing, would be appropriate.; If you have further questions, we will be happy to answer them for you. Sincerely, Rodolfo A. Diaz, Acting Associate Administrator, Moto Vehicle Programs; |
|
ID: aiam2313OpenMr. Charles N. Eblin, Service Director, City of Marion, 685 Delaware Avenue, Marion, OH 43302; Mr. Charles N. Eblin Service Director City of Marion 685 Delaware Avenue Marion OH 43302; Dear Mr. Eblin: This responds to your May 6, 1976, request for permission to remove th brake system from two trucks that were manufactured with brake systems conforming to the requirements of Standard No. 121, *Air Brake Systems*.; From the description of the problems you have encountered with th vehicles, I assume that you do not intend to remove the entire brake system, but only one or more antilock systems installed in satisfaction of the 'no lockup' requirement of S5.3.1 of Standard No. 121. Section 108(a)(2)(A) of the National Traffic and Motor Vehicle Safety Act (15 U.S.C. S 1397(a)(2)(A)) prohibits, with one exception, knowing disconnection of the antilock system by a manufacturer, distributor, dealer, or repair business. Your dealer's refusal to remove the devices is probably based on this prohibition.; A person that does not fall into these categories is not prohibite from disconnection of the systems. Other State or Federal requirements, such as those of the Bureau of Motor Carrier Safety for operation in interstate commerce, may prohibit disconnection. In any case, the NHTSA urges that you not disconnect safety devices without consulting the vehicle manufacturer with regard to the safety configuration of the vehicle.; Sincerely, Frank Berndt, Acting Chief Counsel |
|
ID: aiam2186OpenMr. David Warfield, Box 1207, Easton, Maryland 21601; Mr. David Warfield Box 1207 Easton Maryland 21601; Dear Mr. Warfield: This is in response to your January 21, 1976, request for a interpretation of Federal Motor Vehicle Safety Standard No. 117, *Retreaded Pneumatic Tires*.; You asked whether a retreaded tire may be manufactured with a casin from which the original manufacturer's tire identification number (required by 49 CFR Part 574 and Standard No. 109) has been buffed off, provided the original DOT symbol remains. The answer to your question is yes. The only items of information that are required to be retained from the original casing are the following:; >>>(a) the symbol DOT, (b) the size of the tire, and (c) the actual number of plies or ply rating.<<< A retreaded tire must also, of course, be labeled with the DOT-R symbo and with the retreader's tire identification number, pursuant S6.1 of Standard No. 117 and 49 CFR Part 574.; Yours truly, Richard B. Dyson, Assistant 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.