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: aiam3368OpenMr. G. Montgomery Spindler, Uniroyal, Inc., 1700 K Street, N.W., Washington, DC 20006; Mr. G. Montgomery Spindler Uniroyal Inc. 1700 K Street N.W. Washington DC 20006; Dear Mr. Spindler: This is in response to your letter of October 10, 1980, requestin clarification of the explanation of Treadwear grading in Figure 2 of the Uniform Tire Quality Grading (UTQG) Standards (49 CFR S 575.104). You ask whether the explanation can be interpreted to mean that the relative treadwear performance of different tires on the UTQG test course in San Angelo, Texas will be consistent with the relative performance of the tires when driven under comparable conditions on other roads.; In experimental testing leading to promulgation of the UTQG regulation the National Highway Traffic Safety Administration (NHTSA) tested the treadwear of various tire lines not only on the San Angelo course but on roads in other parts of the country. The agency concluded that the UTQG grades established for different tires in testing on the San Angelo course accurately represent the relative performance of the tires obtainable on roads elsewhere in the United States, assuming that the tires to be compared are run under identical conditions.; The statement in Figure 2 of the UTQG regulation that a tire graded 15 would wear one and one-half times as well on the government course as a tire graded 100 was not intended to suggest that the tire would not wear one and one-half times as well on another course, if conditions of use were controlled. The term 'relative performance' in Figure 2 refers to the performance of tires in comparison to other tires, and the term 'norm' refers to the consistently obtainable relative performance of tires when tested under controlled conditions. Thus, the explanation indicates that, although the relative performance of different tires will be consistent when the tires are tested under controlled conditions, this relative performance may not be obtainable in actual use, if one tire is subjected to more severe road or weather conditions, abusive driving or improper maintenance.; NHTSA will provide confidential treatment for your October 10, 1980 letter.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam3355OpenMr. R.J. Gephart, Director of Safety, City of Phoenix Transit System, P.O. Box 4275, Phoenix, Arizona 85030; Mr. R.J. Gephart Director of Safety City of Phoenix Transit System P.O. Box 4275 Phoenix Arizona 85030; Dear Mr. Gephart: This responds to your letter of August 14, 1980, regarding speedomete requirements on buses. In your letter, you ask us to confirm your belief that buses purchased prior to September 1, 1979, are not required to have speedometers. The key question is the date of manufacture, not the date of purchase. Federal Motor Vehicle Safety Standard (FMVSS) No.127, *Speedometers and Odometers*, requires motor vehicles *manufactured* on or after September 1,1979, to have speedometers that meet certain criteria. Thus, none of your buses that were manufactured before that date are required to have speedometers. To determine the date of manufacture of any of your buses, check the certification label.; We noted your statement that the Phoenix Transit System serves 'onl the Phoenix and surrounding suburbs' passenger population with limited boundaries.' If you begin to offer interstate service, we recommend that you contact the Federal Highway Administration (FHWA), Bureau of Motor Carrier Safety, regarding the regulation of interstate motor carriers. The FHWA may have rules requiring speedometers on all vehicles used in the interstate transportation of passengers. Their address is 400 - 7th St. S.W., Washington, D.C., 20590.; We hope you find this information helpful. Please contact this offic if you have any questions.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam1965OpenMr. Heinz Gerth, Assistant Vice President, Engineering, Mercedes-Benz of North America, Inc., P.O. Box 350, Montvale, NJ 07645; Mr. Heinz Gerth Assistant Vice President Engineering Mercedes-Benz of North America Inc. P.O. Box 350 Montvale NJ 07645; Dear Mr. Gerth: This is in response to your letter of May 5, 1975, asking at what poin the test voltage may be measured during testing for compliance with the Standard No. 103, *Windshield Defogging and Defrosting Systems*, requirement that the blower motor test voltage be 15% over nominal system rating at the blower motor or the supply end of the motor dropping resistor. Your question relates to the meaning of 'the supply end of the motor dropping resistor.'; Measurement of the blower motor test voltage should occur at the suppl side of the motor where there is no resistor. Where the system contains a resistor, the voltage should be measured at the supply side of the resistor, not between the resistor and the motor. The reason for this is that the test voltage level specified in the standard is intended to relate only to the voltage as it is fed into the defrosting and defogging system. The purpose of the voltage level specification is to assure a system capability to handle voltage levels that will normally be encountered during operation of the defroster and defogger. This can be accomplished by measurement of the voltage before the current reaches the resistor.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam5539OpenMr. Takashi Adachi Manager Ichikoh Industries, Ltd. North American Liaison Office 555 Briarwood Circle, Suite 190 Ann Arbor, MI 48108; Mr. Takashi Adachi Manager Ichikoh Industries Ltd. North American Liaison Office 555 Briarwood Circle Suite 190 Ann Arbor MI 48108; Dear Mr. Adachi: This is in reply to your letter of March 14, 1995, t Richard Van Iderstine of this agency, asking for an interpretation of Motor Vehicle Safety Standard No. 108 as it applies to a reflex reflector design that you attached. This design shows a single reflector 2 inches in height mounted behind a clear outer lens which is bisected horizontally by an opaque strip 6mm (.25 in.) wide, giving the impression from the exterior of two reflectors, one .75 in. high above the divider, and one that is 1.00 in. in height, below the divider. You have asked whether the 'structure of the reflex reflector conforms to FMVSS 108,' and whether photometric conformance is judged with respect to the single reflector crossed by the opaque strip, or whether both the upper and lower portions of the bisected reflector must meet the photometric specification. Standard No. 108 is a performance standard, not a design standard. The standard does not specify any requirements concerning the structure of reflectors. The applicable requirements for reflex reflectors are those of SAE Standard J594f Reflex Reflectors January 1977, which Standard No. 108 incorporates by reference. Your reflector should be tested as a single reflector according to the procedures set forth in J594f. If the reflector does not meet the photometric performance requirements of that standard, you may add sufficient reflective elements to the reflector design until conformance is achieved. There is no need to test the upper and lower portions as separate reflectors. If you have any further questions, you may refer them to Taylor Vinson (202) 366-5263 of this Office. Sincerely, John Womack Acting Chief Counsel; |
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ID: aiam2920OpenMr. Sheldon C. Brooks, Marque Motors, 8711 Lyndale Ave., So., Bloomington, MN 55420; Mr. Sheldon C. Brooks Marque Motors 8711 Lyndale Ave. So. Bloomington MN 55420; Dear Mr. Brooks: This is in response to your letter of December 4, 1978, requesting a exemption from the requirements of Part 581, *Bumper Standard*, (49 CFR 581), for ten Lamborghini Countach vehicles currently under construction. You state that the Lamborghini Company's small size and difficult economic situation preclude immediate redesign of the Countach model to bring it into compliance with the bumper regulation.; Federal Motor Vehicle Safety Standard Number 215, *Exterior Protection (49 CFR 571.215), from which Lamborghini had been granted an exemption, was issued under the authority of the National Traffic and Motor Vehicle Safety Act of 1966 (Safety Act). Section 123 of the Safety Act permits the exemption of motor vehicles from safety standard when compliance would cause a manufacturer substantial economic hardship and the manufacturer has attempted in good faith to comply (15 U.S.C. 1410). Standard No. 215 was revoked effective September 1, 1978.; The present bumper regulation, Part 581, effective September 1, 1978 was issued under Title I of the Motor Vehicle Information and Cost Savings Act (Cost Savings Act) (15 U.S.C. 1901), which permits exemptions only for passenger motor vehicles manufactured for a special use. In view of the narrowness of this statutory provision, the National Highway Traffic Safety Administration has no authority to grant an exemption from Part 581 on the basis of economic hardship or limited production.; Part 581 applies to passenger motor vehicles, other than multipurpos vehicles, manufactured on or after September 1, 1978 (49 CFR 581.5(a)). Therefore, vehicles manufactured by Lamborghini which are completed after August 31, 1978, must meet the requirements of the regulation, if they are imported into or sold in the United States.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam5153OpenMr. Carl W. Ruegg President Carlo International, Inc. P.O. Box 250 Selma, CA 93662; Mr. Carl W. Ruegg President Carlo International Inc. P.O. Box 250 Selma CA 93662; Dear Mr. Ruegg: This responds to your letter of March 29, 1993, t Taylor Vinson of this Office. In response to your request for 'information and regulations regarding the importation of non-conforming vehicles for research, investigation, studies, demonstrations,' I enclose a copy of 49 CFR Part 591, the regulation governing the importation of motor vehicles and equipment subject to the regulations of this agency, and a copy of a final rule published March 8, 1993, that amends the regulations. Sections 591.5(j), 591.6(g) (as amended), and 591.7 (as amended) apply to your inquiry. If you have any questions regarding the interpretation of the regulation or amendments, you may contact Mr. Vinson (202-366-5263). Questions regarding the implementation of the regulations, such as the information deemed acceptable to acquire the agency's pre-entry letter of approval, should be addressed to the Office of Vehicle Safety Compliance. You may contact Clive Van Orden with questions of this nature (202-366-2830). Sincerely, John Womack Acting Chief Counsel Enclosure; |
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ID: aiam2458OpenMr. Leon W. Steenbock, Engineering, FWD Corporation, Clintonville, WI 54929; Mr. Leon W. Steenbock Engineering FWD Corporation Clintonville WI 54929; Dear Mr. Steenbock: This responds to FWD Corporation's October 15, 1976, request to kno whether a truck that complies with the requirements of Standard No. 121, *Air Brake Systems*, would continue to comply after the addition of another parking brake system (hand-operated mechanical, operating on the driveline) or another service brake control (piped to either or both sides of a split system).; Standard No. 121's requirements for braking systems does not preclud the addition of an additional braking system. The agency would not consider the requirements of S5.6.4 to prohibit an additional parking brake control.; Standard No. 121 does not prohibit installation of more than on service brake control. The installation of a hand- operated control lever that your letter appears to describe would not of itself violate the standard's requirements. If the hand control were piped into both systems, however, a failure introduced into the control would probably result in violation of S5.7.1, which requires certain secondary braking performance following a single failure introduced into the service brake system.; Sincerely, Frank A. Berndt, Acting Chief Counsel |
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ID: aiam1098OpenMr. R. W. Lillie, R. W. Lillie & Company, 1100 Glendon Avenue, Suite 1449, Los Angeles, CA 90024; Mr. R. W. Lillie R. W. Lillie & Company 1100 Glendon Avenue Suite 1449 Los Angeles CA 90024; Dear Mr. Lillie: Thank you for your letter of April 3, 1973, and your further inquir concerning silicone brake fluids and plastic fuel tanks. Although performance characteristics for silicone brake fluids have not yet been proposed by this agency, we have adopted regulations covering labelling of containers for these fluids. The copy of Standard No. 116 enclosed with your last letter may not have included this latest amendment, a copy of which is enclosed for your information. This constitutes all the information we are presently able to supply concerning silicon brake fluids. However, future rule making action concerning these fluids is scheduled for the near future.; Regarding further actions concerning plastic fuel tanks, we woul advise, as stated in our last letter dated March 29, 1973, that you contact the Bureau of Motor Carrier Safety for further information at the following address:; >>>Director, Bureau of Motor Carrier Safety, Department o Transportation, 400 Seventh Street, S.W., Washington, D.C. 20590; Sincerely, Robert L. Carter, Associate Administrator, Motor Vehicl Programs; |
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ID: aiam2434OpenMr. David Gans, President, Gans Tire Co., Inc., 1003 Broadway, Chelsea, MA 02150; Mr. David Gans President Gans Tire Co. Inc. 1003 Broadway Chelsea MA 02150; Dear Mr. Gans: This responds to your October 12, 1976, question whether th manufacturer recordkeeping requirements of S 574.7 of NHTSA regulations (49 CFR Part 574) may be fulfilled by a tire importer by one or both of the following arrangements: the purchaser records of tires manufactured by company B abroad and imported by Gans would be maintained by company A, the purchaser records of tires manufactured by Company B abroad and imported by Gans would be compiled by Gans but maintained by company B.; Either of these arrangements is acceptable under the language of 574.7(b), which provides that '[e]ach tire manufacturer shall record and maintain or have recorded and maintained for him, the information specified. . . .' this language permits the designation of a person other than the tire manufacturer to maintain the required records. Despite this designation, of course, the ultimate responsibility for maintenance would lie with the importer that qualifies as the manufacturer in the situation you describe.; Sincerely, Frank A. Berndt, Acting Chief Counsel |
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ID: aiam4182OpenMr. T. Chikada, Manager, Automotive Lighting, Engineering Control Dept., Stanley Electric Co. Ltd., 2-9-13, Nakameguro-ku, Tokyo 153, Japan; Mr. T. Chikada Manager Automotive Lighting Engineering Control Dept. Stanley Electric Co. Ltd. 2-9-13 Nakameguro-ku Tokyo 153 Japan; Dear Mr. Chikada: This is in reply to your letter of July 7, 1986, asking for our advic on a decorative lighting device for motorcycles. The general principle remains the same as when I last explained it to you. Please refer to my letter to you dated March 24, 1986 (copy enclosed) on the relationship of paragraph S4.1.3 of Motor Vehicle Safety Standard No. 108 to auxiliary lighting devices for motorcycles. If you conclude that the device would not impair the lighting equipment required by Standard No. 108 then paragraph S4.1.3 would not prohibit your device.; You may follow this guideline with reference to any future question you may have about the permissibility of auxiliary motor vehicle lighting devices. The agency does not approve or disapprove of specific items of lighting equipment.; Sincerely, Erika Z. Jones, 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.