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: aiam0229OpenMr. David Hemenway, 49 Roseland Street No. 3, Cambridge, Ma. 02140; Mr. David Hemenway 49 Roseland Street No. 3 Cambridge Ma. 02140; Dear Mr. Hemenway: Thank you for your letter of March 9, 1970, addressed to the Nationa Highway Safety Bureau, concerning the data provided pursuant to the Consumer Information regulations, 49 CFR S 575.101, Vehicle Stopping Distance. A copy of the consumer information data for 1970 vehicles is enclosed.; You asked whether stopping distances greater than 194 feet for vehicle traveling 60 mph indicate the likelihood that such vehicles are failing to meet Federal Motor Vehicle Safety Standard No. 105. As you have noted, the stopping distance for a constant 20 fpsps deceleration from 60 mps would be 194 feet. However, Standard No. 105 does not require an *average* deceleration rate (including 'lag' or 'build up' time) of 20 fpsps during the entire period of deceleration. The Standard requires only that a vehicle *attain* a deceleration rate of 20 fpsps, with a pedal force of between 15 and 120 lbs., in a stop from 60 mps. Consequently, the Standard does not require that the stopping distance not exceed 194 feet, and consumer information data showing a stopping distance is excess of 194 feet for the 60 mph test does not indicate non-compliance with Standard No. 105.; The attached Discussion Paper indicates some of the revisions i Standard No. 105 that are under consideration. Should amendments be found desirable, a notice of proposed rule making containing then proposed revisions will be issued.; Thank you for your interest in motor vehicle safety. Sincerely, Rodolfo A. Diaz, Acting Associate Director, Motor Vehicl Programs; |
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ID: aiam2575OpenMr. Melvin R. Stahl, Vice President, Government Relations, Motorcycle Industry Council, Inc., 1001 Connecticut Avenue, N.W., Washington, D.C. 20036; Mr. Melvin R. Stahl Vice President Government Relations Motorcycle Industry Council Inc. 1001 Connecticut Avenue N.W. Washington D.C. 20036; Dear Mr. Stahl: This is in reply to your letter of April 7, 1977, requestin interpretations with respect to Motor Vehicle Safety Standard No. 123, *Motorcycle Controls and Displays*.; You have asked whether a speedometer may be marked to register speed i kilometers per hour only. The answer is no. Table 3 of Standard No. 123 requires that motorcycle speedometers indicate speed in miles per hour. You have also asked whether a speedometer may be marked to register speed in both miles and kilometers per hour. The answer is yes. The requirement that speedometers be marked in miles per hour is a minimum requirement only and there is no legal objection to a manufacturer adding kilometer markings to the dial.; "Your next question is whether Standard No. 123 preempts a New Yor State law, passed in 1976, that requires speedometers of all motor vehicles manufactured after September 1, 1980, to measure speeds in both miles and kilometers per hour. The answer is yes, assuming that a j motorcycle is defined as a 'motor vehicle' under New York law. As you know 15 U.S.C. 1392(d) provides that no State shall have authority to establish with respect to a motor vehicle a safety standard applicable to the same aspect of performance of such vehicles as a Federal motor vehicle safety standard. Speedometers marking is clearly the same 'aspect of performance' in both the Federal and New York requirements, and it appears that New York would be preempted from requiring a motorcycle manufacturer to mark its speedometer in kilometers, though the manufacturer would not be prohibited by Standard No. 123 from voluntarily doing so."; Your final question is whether NHTSA contemplates changing Standard No 123 'mandating only or optional km/h speedometer markings.' The answer is yes. I enclose a copy of an NPRM published on December 13, 1976, proposing a new standard on *Speedometers and Odometers*. The proposal specifically allows use of kilometer markings on motorcycle speedometers in addition to the required markings in miles per hour. Note, however, that it would not apply to 'motor driven cycles whose speed attainable in one mile is 30 mph or less' (*e.g.*, mopeds) or police motorcycles.; Sincerely, Frank A. Berndt, Acting Chief Counsel |
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ID: aiam2929OpenHonorable John M. Ashbrook, House of Representatives, Washington, DC 20515; Honorable John M. Ashbrook House of Representatives Washington DC 20515; Dear Mr. Ashbrook: This responds to your December 19, 1978, letter asking whether it i required that school buses be built transport a minimum of 9 passengers.; As you suggest in your letter, there is no requirement that schoo buses be built to transport a minimum of 9 passengers. The school bus safety regulations issued by the National Highway Traffic Safety Administration require the compliance of those vehicles used to transport more than 10 children to or from school and related events. Vehicles with smaller passenger capacities may also transport children to and from school and need not comply with the school bus safety standards.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam2928OpenHonorable John M. Ashbrook, House of Representatives, Washington, DC 20515; Honorable John M. Ashbrook House of Representatives Washington DC 20515; Dear Mr. Ashbrook: This responds to your December 19, 1978, letter asking whether it i required that school buses be built transport a minimum of 9 passengers.; As you suggest in your letter, there is no requirement that schoo buses be built to transport a minimum of 9 passengers. The school bus safety regulations issued by the National Highway Traffic Safety Administration require the compliance of those vehicles used to transport more than 10 children to or from school and related events. Vehicles with smaller passenger capacities may also transport children to and from school and need not comply with the school bus safety standards.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam1962OpenMr. 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: This is in reply to your letter of May 21, 1975, requesting answers t two questions 'relating to the requirements for 16 or 18 gage wire specified by [SAE Standard] J589' ['Turn Signal Switches'] in Motor Vehicle Safety Standard No. 108.; You first asked: >>>'1. Once the switch has met test requirements using the 16 or 1 gage wire, can a switch manufacturer change the wire gage to a smaller or larger size for installation and use on a vehicle?'<<<; We are uncertain as to what you mean. If you intended to refer to th vehicle manufacturer, the answer to the question is yes. He may use a gage other than 16 or 18 when the switch is installed in his vehicle. The test set forth in J589 is a laboratory test measuring voltage drop that must be met by a switch when 16 or 18 gage wire is used.; You next asked: >>>'2. Would a switch which was tested with other than 16 or 18 gag wire (larger or smaller) meet the certification requirements of Part 567 of the federal standards?'<<<; When a manufacturer certifies conformance to Standard No. 108, he i indicating that the turn signal switch will meet the requirements of SAE J589 if tested with 16 or 18 gage wire. He may use any method he chooses to ensure this. This agency does not, through its certification requirements or otherwise, instruct manufacturers how to test their products.; Thank you for your suggestion that we amend Standard No. 108 t incorporate SAE J589 which does not specify the gage of wire for test purposes. We have already proposed adoption of J589b in Notice 3 of Docket No. 69-19.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam2442OpenMr. Charles V. Mulhern, Supervisor, School Bus Inspection, The Commonwealth of Massachusetts, Registry of Motor Vehicle, 100 Nashua Street, Boston, MA 02114; Mr. Charles V. Mulhern Supervisor School Bus Inspection The Commonwealth of Massachusetts Registry of Motor Vehicle 100 Nashua Street Boston MA 02114; Dear Mr. Mulhern: This responds to your June 29, 1976, question whether specific aspect of Massachusett's (sic) requirements for the construction, location, and size of fuel tanks in school buses would be preempted by the Federal requirements for school bus fuel system integrity that become effective April 1, 1977 (Standard No. 301-75, *Fuel System Integrity*). I regret that we have not responded to your questions sooner.; Section 103(d) of the National Traffic and Motor Vehicle Safety Ac (the Act) 15 U.S.C. S1392(d) does preempt State motor vehicle safety requirements of general applicability that are not identical to a Federal standard applicable to the same aspect of performance. In the cases you cite, it appears that the fuel tank seams and the location of the tank are items of design that are identical to the aspects of performance (integrity of the fuel system) regulated by the barrier impact test of Standard No. 301-75. It is the opinion of the NHTSA that these aspects of fuel system construction are preempted by Standard No. 301-75, effective April 1, 1977. In developing the performance requirements of the standard, the agency did not intend to regulate fuel tank size.; The second sentence of S103(d) clarifies that the limitation of safet regulations of general applicability does not prevent governmental entities from specifying additional safety features in vehicles purchased for their own use. Thus the Commonwealth of Massachusetts or its political subdivisions could specify additional fuel system features in the case of public school buses. The second sentence does not, however, permit those governmental entities to specify safety features that prevent the vehicle or equipment from complying with the applicable safety standards. A school bus manufacturer must continue to comply with all applicable standards.; Sincerely, Frank A. Berndt, Acting Chief Counsel |
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ID: aiam5124OpenMr. Frank E. Timmons Rubber Manufacturers Association 1400 K St., N.W. Washington, DC 20005; Mr. Frank E. Timmons Rubber Manufacturers Association 1400 K St. N.W. Washington DC 20005; "Dear Mr. Timmons: This responds to your letter about our November 199 letter to the Under Secretary, Kuwait Ministry of Commerce. In that letter, NHTSA discussed Federal requirements for tires sold in the United States for passenger cars and other 'motor vehicles.' You wish to ensure that the Under Secretary understands that the term 'motor vehicles' only refers to vehicles 'manufactured primarily for use on highways.' We are glad to clarify the meaning of the term 'motor vehicle.' 'Motor vehicle' is defined in 102(3) of the National Traffic and Motor Vehicle Safety Act as 'any vehicle driven or drawn by mechanical power manufactured primarily for use on the public streets, roads, and highways, except any vehicle operated exclusively on a rail or rails.' (Emphasis added.) Thus, a motor vehicle is a vehicle that the manufacturer expects will use public highways as part of its intended function. This agency has issued many interpretations of what is and what is not a 'motor vehicle.' In general, vehicles that are equipped with tracks or are otherwise incapable of highway travel are not motor vehicles. Likewise, vehicles that are designed and sold solely for off-road use (e.g., airport runway vehicles and underground mining vehicles) are not motor vehicles even if operationally capable of highway travel. They would, however, be considered motor vehicles if the manufacturer knew that a substantial proportion of its customers actually would use them on the highway. Vehicles that use the public highways on a necessary and recurring basis are considered motor vehicles. Furthermore, even if the majority of a vehicle's use will be off-road but it will spend a substantial amount of time on-road, this agency has interpreted that to be a motor vehicle. We appreciate your interest in this matter and will provide the Under Secretary with a copy of this letter. Please contact us if we can be of further assistance. Sincerely, John Womack Acting Chief Counsel cc: Under Secretary, Kuwait Ministry of Commerce"; |
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ID: aiam2410OpenMr. 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: This is a reply to your letter of September 16, 1976, referencing a opinion letter to you dated October 21, 1969, and asking whether it conflicts with an opinion letter to Ford Motor Company dated 'December 5, 1975'. (The true date of the letter is July 7, 1975, we do not know why your copy is dated otherwise).; The 1969 letter informed you that 'if one compartment or lamp [in multicompartment lamp] meets the photometric requirements [of Standard No. 108] the additional compartments or lamps are considered as additional lamps and are, therefore not regulated by . . . Standard No. 108 except by S3.1.2.'. The letter also stated that 'lamps on a vehicle and not required by this standard are generally subject to regulation by the States.' Our 1975 letter to Ford, on the other hand advised the company in effect that the performance of the entire multicompartment assembly was covered by Standard No. 108, and that section 25950(b), of the California Vehicle Code was preempted by it. You have asked whether our letter to Ford conflicts with our earlier letter to you.; There is no present conflict. In an amendment to Standard No. 10 effective January 1, 1973, (copy enclosed) the agency adopted paragraph S4.1.1.12 and figure 1 which established minimum photometric requirements that must be met by multicompartment tail, stop, and turn signal lamps. The act of establishing requirements for the additional compartments in a multicompartment lamp thus voided the 1969 letter to you and the interpretation to Ford is the correct one.; The Monarch taillamp, therefore, must meet the requirements of Table of standard No. 108 and is not a lamp that is 'in addition to the minimum required number' as that term is used in California Vehicle Code section 25950(b), which appears to have been amended in an effort to include it.; We appreciate your suggestion on an amendment to Standard No. 108 o lens color.; Sincerely,Frank A. Berndt, Acting Chief Counsel |
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ID: aiam0650OpenMr. Edward P. Shear, President, Champion Carriers, Inc., P.O. Box 2651, Tulsa, OK 74101; Mr. Edward P. Shear President Champion Carriers Inc. P.O. Box 2651 Tulsa OK 74101; Dear Mr. Shear: This is in response to your letter of January 25, 1972, wherein yo state that you manufacture 'off-highway vehicles for cranes, drill rigs and truck terminals' and request that we advise you of the requirements regarding manufacturer registration which became effective February 1, 1972. In a telephone conversation with Mr. David Fay of NHTSA on March 23, 1972, you indicated further that the type of vehicle you manufacture is represented by the picture at the bottom of your January 25 letter to us.; We would not consider these vehicles to be 'off-highway vehicles.' I our view they appear to be similar to truck tractors, and have a primary purpose of transporting other vehicles (which may be off-highway vehicles) over the public roads. Consequently, we would consider them to be trucks under the National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1381 *et seq*.) and the motor vehicle safety standards and regulations issued pursuant to the Act.; As a manufacturer of such vehicles you must comply with th Manufacturer Identification regulations (49 CFR Part 566) and a copy of them is enclosed as you requested. Also enclosed is a copy of the National Traffic and Motor Vehicle Safety Act, and information on how to obtain copies of the Motor Vehicle Safety Standards and regulations.; If you have further questions, please write. Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam0954OpenJohn M. Carter, Esquire, messrs. Carter and Carter, 229 John Street, Clayton, NY 13624; John M. Carter Esquire messrs. Carter and Carter 229 John Street Clayton NY 13624; Dear Mr. Carter: This is in reply to your letter of December 14, 1972, to the Federa Highway Administration on behalf of your client, a snow plow dealer. You ask for verification 'that the addition of a snow plow to a completed truck is considered the addition of a readily attached component and does not require recertification.'; We confirm that a person adding a snow plow to a completed truck is no a final-stage manufacturer who is required by 49 CFR Part 568 to certify compliance of the vehicle with Federal motor vehicle safety standards. He is, however, responsible for insuring that the modified vehicle complies with Standard No. 108 before delivering it to its purchaser.; 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.