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: aiam0653OpenMr. Heinz W. Gerth, Assistant Vice President, Mercedes-Benz of North America, Inc., 158 Linwood Plaza, Fort Lee, NJ 07028; Mr. Heinz W. Gerth Assistant Vice President Mercedes-Benz of North America Inc. 158 Linwood Plaza Fort Lee NJ 07028; Dear Mr. Gerth:#On November 9, 1971, you wrote concerning th requirement in Standard No. 101 that a control be provided to adjust the intensity of control illumination, continuously variable from an 'off' position to a position providing illumination sufficient for the vehicle operator to readily identify controls under conditions of reduced visibility. You asked an interpretation that 'the term 'off' means a control position which provides minimal control illumination which is not distracting to the driver who has adapted to dark ambient roadway conditions.'#In our opinion, the word 'off' means a control position providing no illumination, and we therefore do not concur in your interpretation. You have asked, however, as an alternative, that your letter be considered as a petition for rulemaking to amend Standard No. 101 to provide an option permitting the type of control already incorporated in Mercedes-Benz vehicles.' We have tentatively determined that your petition has merit, and that quantitative levels for control illumination intensity should be established in Standard No. 101. We shall therefore initiate appropriate rulemaking with a proposed effective date of September 1, 1973.#Sincerely, Douglas W. Toms, Administrator; |
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ID: aiam0472OpenMr. H. A. Sage, Director of Research and Engineering, Truck- Lite Company, P. O. Box 387, Jamestown, NY, 14701; Mr. H. A. Sage Director of Research and Engineering Truck- Lite Company P. O. Box 387 Jamestown NY 14701; Dear Mr. Sage: This is in reply to your letter of October 14, 1971, to Mr. Lewis Owe of this Office concerning an interpretation regarding your Truck-Lite No. 127 license plate light.; The requested interpretation concerns the 8 degree incident light angl specified in SAE J587, 'License Plate Lamps,' as follows:; >>>'When a single lamp is used to illuminate the plate, the lamp an license plate holder shall bear such relation to each other that at no point on the plate will the incident light make an angle of less than 8 deg to the plane of the plate.'<<<; Since the 8 degree incident light angle is also a requirement o Federal Motor Vehicle Safety Standard No. 108, all license plate lamp designs must conform to it. It is our position that the angle be measured from the optical center of the lens, therefore, the Electrical Testing Laboratories' position is valid. That is, the incident light angle of your lamp, without the paint shield and when mounted as it will be installed on the vehicle, is below the 8 degree minimum requirement.; Sincerely, E. T. Driver, Director, Office of Operating Systems, Moto Vehicle Programs; |
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ID: aiam0095OpenMr. Warren M. Heath, Commander, Engineering Section, Department of California Highway Patrol, P.O. Box 898, Sacramento, CA 95804; Mr. Warren M. Heath Commander Engineering Section Department of California Highway Patrol P.O. Box 898 Sacramento CA 95804; Dear Mr. Heath: Thank you for your letter of July 1, 1968, to Mr. George C. Nield concerning a clarification of paragraph S 3.4.3 of Federal Motor Vehicle Safety Standard No. 108.; Paragraph S 3.4.3 specifies that, as a minimum, the taillamps shall b illuminated when the headlamps are illuminated, except when the headlamps are being flashed. The phrase 'except when the headlamps are being flashed', permits the vehicle manufacturer to use a separate switch or flasher for illuminating the headlamps only when it would not be appropriate or in the interest of safety to simultaneously illuminate the taillamps and headlamps. In addition to the examples cited in your letter, such devices could also be used for flashing the headlamps on public transit vehicles to indicate an emergency situation.; Since the subject matter of S 3.4.3 is taillamps and since Federa Standard No. 108 is otherwise silent as to headlamp flashing, this matter appears to be within the purview of the California vehicle code.; Thank you for your continued interest in the motor vehicle safet standards.; Sincerely, David A. Fay, Office of Standards on Accident Avoidance Motor Vehicle Safety Performance Service; |
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ID: aiam0126OpenMr. Jim Tydings, Chief Engineer, Perley A. Thomas Car Works, Incorporated, High Point, NC 27261; Mr. Jim Tydings Chief Engineer Perley A. Thomas Car Works Incorporated High Point NC 27261; Dear Mr. Tydings: Thank you for your letter of November 19, 1968, to Mr. E. Leysath o this Bureau, concerning a clarification of the requirements of paragraph S3.4.3 of Federal Motor Vehicle Safety Standard No. 108.; As you indicated, paragraph S3.4.3 of initial Standard No. 108, whic was published in the *Federal Register* on February 3, 1967, required that tail lamps, license plate lamps, and side marker lamps be illuminated when the headlamps are illuminated. The effective date of the initial standard was January 1, 1968. However, on December 16, 1967, an amendment to the initial standard was published in the *Federal Register*. This amendment delayed the effective date of paragraph S3.4.3 until May 1, 1968, and in addition revised that paragraph to require, as a minimum, that the fail (sic) lamps be illuminated when the headlamps are illuminated. Therefore, the requirements of paragraph S3.4.3 were not applicable to vehicles manufactured during the period of January 1, 1968 through April 30, 1968. During that period, selection of the lamp switching arrangement was at the option of the vehicle manufacturer.; Thank you for writing. Sincerely, Charles A. Baker, Office of Standards on Accident Avoidance Motor Vehicle Safety Performance Service; |
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ID: aiam3087OpenMr. Ron Bechtel, Halliburton Services, Drawer 1431, Ducan, Oklahoma 73533; Mr. Ron Bechtel Halliburton Services Drawer 1431 Ducan Oklahoma 73533; Dear Mr. Bechtel: This is in response to your letter of May 1, 1979, requesting a interpretation of the definition of 'incomplete vehicle' contained in Federal Motor Vehicle Safety Standard No. 115, and in confirmation of your subsequent telephone conversations with Mr. Schwartz of my office.; The term 'incomplete vehicle' is defined in S3 of the standard to mea 'an assemblage consisting, as a minimum, of frame and chassis structure, power train, steering system, suspension system, and braking system, to the extent that those systems are to be part of the completed vehicle, that requires further manufacturing operations, other than the addition of readily attached components, such as mirrors or tire and rim assemblies, or minor finishing operations such as painting, to become a completed trailer.; You are correct in saying that most of the components listed in th definition are not meant to be part of a trailer. Consequently, an incomplete Trailer would consist of only those components, such as a frame, listed in the definition which are meant to be part of the completed trailer. The outfitting of an incomplete trailer for a specific purpose would not be sufficient to make Halliburton Serviced responsible for assigning the vehicle identification number.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam0097OpenMr. Toyotaro Yamada, Manager, Toyota Motor Company, Limited, 231 Johnson Avenue, Newark, NJ 07108; Mr. Toyotaro Yamada Manager Toyota Motor Company Limited 231 Johnson Avenue Newark NJ 07108; Dear Mr. Yamada: Thank you for your letter of July 23, 1968, to Mr. George C. Nield Acting Director, Motor Vehicle Safety Performance Service, concerning the requirements for turn signal and hazard warning signal flashers as specified by Motor Vehicle Safety Standard No. 108.; With certain exceptions, paragraph S3.3 of Standard No. 108 permits th use of combination lamps, reflective devices and items of associated equipment, provided the requirements for each lamp, reflective device and item of associated equipment are met. Therefore, a combination turn signal and hazard warning signal flasher may be used, provided the requirements for each signal (turn and hazard warning) are met.; You are correct in your understanding that Standard No. 108 an basically referenced SAE Standards J590 and J945 do not require operation of the flasher unit with only one signal bulb in the test circuit. The standard test circuit shown in Figure I of SAE Standard J823 indicates a minimum of two signal lamps and one pilot indicator lamp as the lamp load.; Thank you for writing. Sincerely, David A. Fay, Office of Standards on Accident Avoidance Motor Vehicle Safety Performance Service; |
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ID: aiam1409OpenMr. J.C. Eckhold, Director, Automotive Safety Office, Ford Motor Company, The American Road, Detroit, MI, 48121; Mr. J.C. Eckhold Director Automotive Safety Office Ford Motor Company The American Road Detroit MI 48121; Dear Mr. Eckhold: This is in reply to your letter of January 24, 1974, asking for a interpretation as to whether a rear lamp assembly design that Ford demonstrated to NHTSA representatives conforms to the location requirements of Standard No. 108. The assembly consists of three units which, from outboard to inboard, as a rear lighting assembly, comprise the tail lamp/stop lamp, backup lamp, and turn signal lamp.; Standard No. 108 specifies that stop lamps, tail lamps, and turn signa lamps be 'as far apart as practicable.' The standard does not specify a minimum separation distance of lamps, a maximum permissible location inboard, or location of one system relative to another. The determination of practicability in lamp spacing is to be made by the vehicle manufacturer, and the agency has generally afforded manufacturers some latitude in this interpretation.; Therefore, the configuration you have described and demonstrated woul not violate Standard No. 108. It should be noted, however, that it would be in conflict with the requirements for rear turn signals and stop lamps as proposed in Docket 69-19, Notice 3.; Sincerely, James B. Gregory, Administrator |
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ID: aiam4095OpenMr. Earnest Farmer, Director of Pupil Transportation, Tennessee Department of Education, Nashville, TN 37219-5335; Mr. Earnest Farmer Director of Pupil Transportation Tennessee Department of Education Nashville TN 37219-5335; Dear Mr. Farmer: This responds to your February 19, 1986 letter to the National Highwa Traffic Safety Administration (NHTSA) asking whether Federal motor vehicle safety standards prohibit commercial businesses from using fiberglass on the exterior of school buses. As explained below, the answer to your question is no.; The National Traffic and Motor Vehicle Safety Act authorizes NHTSA t issue minimum performance standards for school buses. Our safety standards do not specify the materials to be used for the exterior of school buses. However, the materials chosen by a manufacturer must be strong enough to enable the bus to meet the requirements of those standards. Among those requirements are the rollover protection ones of Standard No. 220, fuel system requirements of Standard No. 301, and strength requirements of Standard No. 221, *School Bus Body Joint Strength*, for body panel joints on school buses with gross vehicle weight ratings over 10,000 pounds. Manufacturers of new school buses using fiberglass for school bus exteriors must certify that their vehicles conform to the requirements of all applicable school bus safety standards.; I hope this information is helpful. Please contact my office if yo have further questions.; Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam1928OpenMr. Harold D. Jones, Bock & Jones, 435 Main Street, New Madrid, MO 63869; Mr. Harold D. Jones Bock & Jones 435 Main Street New Madrid MO 63869; Dear Mr. Jones: This is in response to your letter of May 2, 1975, inquiring about th existence of regulations governing the manufacture, design, and on-the-road operation of trailers used to transport fertilizer while hitched to a pickup truck.; The National Highway Traffic Safety Administration has th responsibility of promulgating safety standards that set minimum performance requirements for vehicles manufactured and/or sold in the United States. There are five motor vehicle safety standards that apply to trailers. These standards relate to trailer lighting, tires, and braking systems (Standard No. 106-74, *Brake Hoses* (49 CFR Part 571.106), Standard No. 108, *Lamps, Reflective Devices and Associated Equipment* (49 CFR Part 571.108), Standard No. 116, *Motor Vehicle Brake Fluids* (49 CFR Part 571.116), Standard No. 119, *New Pneumatic Tires for Vehicles Other Than Passenger Cars* (49 CFR Part 571.119), Standard No. 121, *Air Brake Systems* (49 CFR Part 571.121)).; There is no safety standard that applies to the towing of a trailer The use of a safety chain to guard against release of the trailer may, however, be mandated by state law.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam1390OpenMr. L. A. Volberding, Administrative Manager, KAR-KRAFT, INC., 10611 Haggerty Street, Dearborn, MI 48126; Mr. L. A. Volberding Administrative Manager KAR-KRAFT INC. 10611 Haggerty Street Dearborn MI 48126; Dear Mr. Volberding: This is in reply to your letter dated December 6, 1973, in which yo ask whether there is a distinction between the reference to the 'lowest seating position' for motorcycles in S5.1.2.1 of Motor Vehicle Safety Standard No. 205, and the reference to 'lowest seating surface' in proposed 'Fields of Direct View' (Docket No. 70-7, Notice 2, 37 FR 7210, April 12, 1972). You also request an explanation for the difference between the reference to 15 inches above the seating surface in Standard No. 205, and 18 inches in Docket No. 70-7.; The notice in Docket No. 70-7, as you may know, has been withdrawn (3 FR 6194, March 7, 1973). However, we would consider the phrase 'lowest seating position' to be synonymous with 'lowest seating surface' with respect to these particular items. The 18-inch requirement proposed in Docket No. 70-7 represented a more recent evaluation than the 15-inch requirement in Standard No. 205 of the minimum desirable area for motorcycle visibility. Had that requirement become effective the agency would have taken steps to ensure that the requirements were consistent with each other.; 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.