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: aiam0572OpenMr. Bob Lockwood, Enterprise Sky Park, Tarmac Road, Redding, California 96001; Mr. Bob Lockwood Enterprise Sky Park Tarmac Road Redding California 96001; Dear Mr. Lockwood: This is in reply to your letter of January 20, 1972, regardin standards for retreaded automobile and truck tires.; Federal motor vehicle safety standards do not apply to aircraft o aircraft equipment.; Standard No. 117 entitles 'Retreaded Pneumatic Tires - Passenger Cars, does not apply to the retreading of aircraft tires and does not supersede Advisory Circular 43.13-1. A copy of the standard is enclosed.; We do not have a safety standard for retreaded truck tires at thi time.; Thank you for your inquiry. Sincerely, E.T. Driver, Director, Office of Operating systems, Moto Vehicle Programs; |
|
ID: aiam4531OpenMr. Paul A. Reneau 9261 North 60th Street Brown Deer, WI 53223; Mr. Paul A. Reneau 9261 North 60th Street Brown Deer WI 53223; "Dear Mr. Reneau: This is a response to your undated letter which thi agency received in January 1988. I apologize for the delay in this response. In your letter, you presented a schematic and an engineering explanation of a power window system design and operation, and asked whether the system meets Federal safety standard 118, Power-operated Window Systems (49 CFR 571.118). Based on my understanding of the information enclosed with your letter, it appears that your power window system would comply with Standard 118. As I understand your system description, there are two electrical circuits that control power window operations. In the principal circuit, when the vehicle ignition key system is in the 'ON' or 'ACCESSORY' position, the power windows are operable. In most power-operated window systems, turning the ignition key to the 'OFF' position means that the power windows no longer are operable. However, in your system, a second, parallel circuit connects to the power window motor, and provides an energy source to allow an operator to close a power window when the ignition key is in the 'OFF' position. The parallel energy source permits operation only for a limited time period controlled by the electronic circuitry. My understanding is that with your design, the parallel circuit includes door switches which stop power window operation irrespective of the ignition key system position, whenever either vehicle front door is opened during the window closing sequence. According to your diagram and explanation, in such a circumstance, an operator must close the door, and return the ignition key to the 'ON' or 'ACCESSORY' position to reactivate the power window system. Paragraph S3 of Standard 118 specifies that power window systems may be closed only under certain listed conditions. One of those conditions is when the ignition key is in the 'ON' or 'ACCESSORY' position, as specified in S3(a). When the ignition key is in the 'OFF' position, the power windows may be closed only under the conditions described in S3(b) (by muscular force unassisted by a vehicle power source), S3(c) (upon activation of a key-locking system on the exterior of the vehicle), or S3(d). Paragraph S3(d) reads as follows: During the interval between the time the locking device which controls the activation of the vehicle's engine is turned off and the opening of either of a two-door vehicle's doors or, in the case of a vehicle with more than two doors, the opening of either of its front doors. Based on my understanding of the information you supplied, the only time the power windows in your system can be closed with the ignition key in the 'OFF' position is during the interval between engine deactivation and opening of either of the vehicle's front doors. Standard 118 expressly permits this, so your system appears to comply with that standard. I hope you find this information helpful. If you have further questions, please contact Joan F. Tilghman of my staff at this address or by telephone at (202) 366-2992. Sincerely, Erika Z. Jones Chief Counsel"; |
|
ID: aiam1733OpenMr. J.B. Markovich, General Manager, Utility Trailer Sales Co., Railroad and Orange Ave., P.O. Box 3258, Fresno, CA 93776; Mr. J.B. Markovich General Manager Utility Trailer Sales Co. Railroad and Orange Ave. P.O. Box 3258 Fresno CA 93776; Dear Mr. Markovich: This responds to your December 6, 1974, request for a determinatio whether a bulk transport trailer designed for transporting farm commodities from the field to processing plants over private and public roads, qualifies for exemption from Standard No. 121, *Air brake systems*, as an agricultural vehicle.; The vehicle you describe does not qualify as an agricultural vehicl that is excepted from Federal motor vehicle safety standards. The National Traffic and Motor Vehicle Safety Act of 1966 defines motor vehicle as follows:; >>>'Motor vehicle' means any vehicle driven or drawn by mechanica power manufactured primarily for use on the public streets, roads, and highways, except a vehicle operated exclusively on a rail or rails.<<<; We have interpreted this language to mean that a motor vehicle is vehicle which the manufacturer expects to be used on the public highways as part of its intended function. This would include most agricultural vehicles. However, the legislative history of the original Safety Act and S 301 indicate that congress did not intend agricultural machinery to be subject to the safety standards. We have interpreted agricultural machinery to include only vehicles designed as 'implements of husbandry' to perform strictly agricultural functions on farmland. The category does not extend to all vehicles engaged in transporting agricultural products.; The bulk transport trailer you describe appears designed expressly t rransport (sic) the product of an agricultural machine from the field to processing plants over the highways. It does not, therefore, qualify as an agricultural machine.; To expedite any questions you may have regarding the procedure fo temporary exemption, I would advise you to call Mr. Taylor Vinson of this office at (202)426-9511.; Yours truly, Richard B. Dyson, Acting Chief Counsel |
|
ID: aiam0821OpenMr. Louis C. Lundstrom, Director, Automotive Safety Engineering, General Motors Corporation, General Motors Technical Center, Warren, MI 48090; Mr. Louis C. Lundstrom Director Automotive Safety Engineering General Motors Corporation General Motors Technical Center Warren MI 48090; Dear Mr. Lundstrom: This is in reply to your letter of August 21, 1972, on the subject o the operation of the seat belt warning system when the vehicle is in one of the free start modes allowed by S7.4.3 and S7.4.4 of Standard No. 208.; You are correct in your understanding that S7.3.5.4 does not requir the warning to operate when the ignition switch is in the 'start' position if the conditions described in S7.4.3 and S7.4.4 exist. Under those conditions, the interlock system continues to act as if the operation of the belt systems had not been followed by their release. By the same logic, the warning system activation required by S7.3.5.4 is in abeyance until the ending of the free start conditions.; Sincerely, Richard B. Dyson, Assistant Chief Counsel |
|
ID: aiam1699OpenMr. Scott B. Miller, Hadco Engineering, 2000 Camfield Avenue, Los Angeles, CA 90040; Mr. Scott B. Miller Hadco Engineering 2000 Camfield Avenue Los Angeles CA 90040; Dear Mr. Miller: This responds to your November 13, 1974, question whether a combinatio vehicle which consists of an air braked truck tractor and an electrically-braked trailer would be subject to the requirements of Standard No. 121, *Air brake systems*, effective January 1, 1975, for trailers and March 1, 1975, for trucks and buses. The electric brakes on the trailer would be actuated by a Warner Electric brake controller that is designed to be mounted in the truck's air control line and to respond to air brake signals generated by the truck's service brake control.; Standard No. 121 applies to trucks, buses, and trailers equipped wit air brake systems. Therefore, the trailer which is electrically-braked is not required to comply with the standard.; It appears from the Warner literature that you enclosed that the truc tractor would be equipped with air brakes and would therefore have to comply with the standard. I would like to point out that air-braked truck tractors manufactured after March 1, 1975, must be certified to comply with the requirements of the air brake standard. If a person modifies the air brake lines on such a truck tractor before the first retail purchase by the addition of the Warner controller, that person must certify that the truck still meets the standard as modified.; Yours truly, Richard B. Dyson, Acting Chief Counsel |
|
ID: aiam4161OpenMr. Gary D. Clark, John Deere Tractor Works, P.O. Box 3500, Waterloo, IA 50704-3500; Mr. Gary D. Clark John Deere Tractor Works P.O. Box 3500 Waterloo IA 50704-3500; Dear Mr. Clark: This responds to your letter dated February 27, 1986, concerning you projected sale of a strip chassis for the class A motor home industry. The identifying information submitted in your letter is being referred to the Office of Vehicle Safety Standards which keeps records of manufacturer identification in accordance with 49 CFR Part 566.; Under S114 of the National Traffic and Motor Vehicle Safety Act o 1966, as amended, each manufacturer is responsible for certifying that its motor vehicles and motor vehicle equipment comply with all applicable safety standards. This agency does not require that a manufacturer's documents and test data, which form the basis for this certification, be submitted unless requested by the agency.; I hope this information is helpful to you. Sincerely, Erika Z. Jones, Chief Counsel |
|
ID: aiam1363OpenMr. Evan Hammond, Manager - Central Engineering, Trailmobile Technical Center, 5570 Creek Road, Cincinnati, OH, 45242; Mr. Evan Hammond Manager - Central Engineering Trailmobile Technical Center 5570 Creek Road Cincinnati OH 45242; Dear Mr. Hammond: This is in reply to your letters of October 25, and December 14, 1973 I regret that your earlier letter did not arrive.; You stated that your customer wishes to mount rear identification lamp at the same height from the ground as the rear turn signal, stop, tail and clearance lamps, and that, because of the shallowness of the rear header area it is not 'practicable' to mount them there.; Although it may not be 'practicable' to mount the Grote 272 lamp, specified by your customer, in the header area, there may b other conforming lamps that it would be 'practicable' to mount in that location in a three-lamp identification array. If such lamps are available, then Standard No. 108 takes priority over contractual specifications, especially since the clearance lamps will be mounted at a point other than 'as close as practicable to the top of the vehicle'.; Yours truly, Richard By. Dyson, Assistant Chief Counsel |
|
ID: aiam1676OpenMemorandum to Interpretation of Certification Regulations (49 CFR Part 567), From Acting Chief Counsel, Subject: Files; Memorandum to Interpretation of Certification Regulations (49 CFR Part 567) From Acting Chief Counsel Subject: Files; In a letter recently mailed by this agency in a current enforcemen action, the following interpretation of 49 CFR Part 567 appeared:; '567.5(g) - The information on the label is not presented in th specified order or form. Your use of a vehicle model designation within the body of the label is unacceptable. However, it is permissible to list your vehicle model after the last statement, which is the vehicle type.'; Richard B. Dyson |
|
ID: aiam0964OpenMr. W. G. Milby, Project Engineer, Blue Bird Body Company, Fort Valley, GA 31030; Mr. W. G. Milby Project Engineer Blue Bird Body Company Fort Valley GA 31030; Dear Mr. Milby: In our letter to you of December 7, 1972, regarding Standard 217, Bu Window Retention and Release, we incorrectly stated in the answer to question 5 that an amendment currently being prepared would clarify Figures 1 and 2 to indicate the location of the bus wall in relation to the seat. We do not feel such a clarification is necessary for the purposes of the standard. The intent of those figures is to establish a space envelope containing certain reach distances with respect to the seat, and the location of the wall is therefore not relevant.; Sincerely, Richard B. Dyson, Assistant Chief Counsel |
|
ID: aiam2959OpenMr. Frank Tedesco, President, Lifetime Foam Products, Inc. 3001 Cullerton Drive, Franklin Park, IL 60131; Mr. Frank Tedesco President Lifetime Foam Products Inc. 3001 Cullerton Drive Franklin Park IL 60131; Dear Mr. Tedesco: This is in response to your letter of February 8, 1979, requestin confirmation of your understanding of an October 7, 1976, letter of interpretation by our office concerning Safety Standard No. 207, *Seating Systems*. You are correct in your assumption that the standard applies only to completed vehicles and not to vehicle seats as individual equipment.; Sincerely, Frank Berndt, 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.