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: aiam3224OpenMr. C. Crissy, Manager, Mechanical Products, Aeroquip Corporation, 300 South East Avenue, Jackson, MI 49203; Mr. C. Crissy Manager Mechanical Products Aeroquip Corporation 300 South East Avenue Jackson MI 49203; Dear Mr. Crissy: This responds to your Janaury 17, 1980, letter asking whether th performance requirements of the parking brake sections of Standard No. 121, *Air Brake Systems*, permit the use of a common piston for both the service and parking brakes.; In our August 9, 1979, Federal Register notice (44 FR 46850), we state that the performance requirements of the parking brake system must be achieved with any single leakage- type failure in the service brake system, including a ruptured diaphragm. The use of the diaphragm example was intended only to clarify a question that had been raised by a commenter to the notice proposing the parking brake amendment. The diaphragm example does not limit the requirement that any single leakage- type failure of a component of the service brake system must not affect the peformance of the parking brake system.; With respect to your question, you state that a piston does not fail i the sudden manner of a diaphragm. Although this may be accurate, it is not the correct approach for interpretation of the performance requirements of the parking brake sections of the standard. If your parking brake system would comply with the requirements of the standard once the piston in the service brake system has failed, then you would be permitted to use a common piston. If, on the other hand, a failure of the service brake piston would cause the parking brake system to fail the requirements, a common piston would not be allowed.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam2937OpenMr. James R. Randolph, 765 Malley Drive, Northglenn, CO 80233; Mr. James R. Randolph 765 Malley Drive Northglenn CO 80233; Dear Mr. Randolph: This responds to your December 28, 1978, letter concerning an auxiliar fuel tank installed by the dealer on a 1978 Ford van that you purchased. You are concerned that the auxiliary tank represents a safety hazard due to the location of the tank's filler cap in the left rear wheel-well.; Federal Motor Vehicle Safety Standard No. 301-75, *Fuel Syste Integrity* specifies performance requirements for fuel systems on motor vehicles. Although the standard applies to completed vehicles rather than to fuel tanks or other fuel system components, your dealer had to assure that your van complied with the standard. A person who mounts an auxiliary fuel tank on a new motor vehicle before the vehicle's first purchase in good faith for purposes other than resale is a vehicle alterer under National Highway Traffic Safety Administration regulations. That person is required by 49 CFR 567.7 to affix a label to the vehicle stating that, as altered, the vehicle conforms to all applicable Federal motor vehicle safety standards--including Safety Standard No. 301-75. Therefore, there should be an 'alterer' label on your van in addition to the certification label placed on the vehicle by the original manufacturer.; Even if the vehicle complies with Safety Standard No. 301-75, th location and design of the auxiliary fuel tank could constitute a safety-related defect for which the manufacturer would also be responsible. I am, therefore, forwarding a copy of your letter to the agency's Office of Defects Investigation. That office will examine this situation and may be in touch with you at a later date.; Thank you for your letter and for bringing this matter to ou attention.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam1022OpenMs. Claire Cannon, Center for Auto Safety, Post Office Box 7250, Washington, DC 20044; Ms. Claire Cannon Center for Auto Safety Post Office Box 7250 Washington DC 20044; Dear Ms. Cannon: This is in reply to your letter of February 14, 1973, concerning ou plans for publicizing the new Federal odometer requirements.; To begin with your third question, the NHTSA does not have th authority to require State departments of motor vehicles to notify the public of the odometer requirements. Because the participation of the States is voluntary, and not subject to regulation, we have not attempted to instruct the States in our regulatory notices. The approach you suggested, of sending notice of the Federal law with the auto registration cards, would be useful, particularly in States whose forms cannot be readily converted to contain the disclosure statement. This is one of the publicity measures that we are discussing with the States at the present time.; In the short run, we are going to have to rely on the public media t distribute information about the requirements. We issued press releases upon issuance of the notices establishing the requirement, and have been encouraging the press to highlight the problems of odometer tampering and to tell of the existence of the disclosure requirements. These efforts fall short, however, of providing the type of general coverage needed for regulations having a national effect. It is likely that most consumers will learn of the requirements from automobile dealers, most of whom have been advised of the requirements by their national dealer associations.; The problem of odometer fraud deserves full exposure, and we intend t do what we can to expose it. The scale of our long term efforts, however, including the question of the use of TV spots, is a matter that has not been resolved as yet.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam2938OpenMr. James R. Randolph, 765 Malley Drive, Northglenn, CO 80233; Mr. James R. Randolph 765 Malley Drive Northglenn CO 80233; Dear Mr. Randolph: This responds to your December 28, 1978, letter concerning an auxiliar fuel tank installed by the dealer on a 1978 Ford van that you purchased. You are concerned that the auxiliary tank represents a safety hazard due to the location of the tank's filler cap in the left rear wheel-well.; Federal Motor Vehicle Safety Standard No. 301-75, *Fuel Syste Integrity* specifies performance requirements for fuel systems on motor vehicles. Although the standard applies to completed vehicles rather than to fuel tanks or other fuel system components, your dealer had to assure that your van complied with the standard. A person who mounts an auxiliary fuel tank on a new motor vehicle before the vehicle's first purchase in good faith for purposes other than resale is a vehicle alterer under National Highway Traffic Safety Administration regulations. That person is required by 49 CFR 567.7 to affix a label to the vehicle stating that, as altered, the vehicle conforms to all applicable Federal motor vehicle safety standards--including Safety Standard No. 301-75. Therefore, there should be an 'alterer' label on your van in addition to the certification label placed on the vehicle by the original manufacturer.; Even if the vehicle complies with Safety Standard No. 301-75, th location and design of the auxiliary fuel tank could constitute a safety-related defect for which the manufacturer would also be responsible. I am, therefore, forwarding a copy of your letter to the agency's Office of Defects Investigation. That office will examine this situation and may be in touch with you at a later date.; Thank you for your letter and for bringing this matter to ou attention.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam2935OpenMr. James R. Randolph, 765 Malley Drive, Northglenn, CO 80233; Mr. James R. Randolph 765 Malley Drive Northglenn CO 80233; Dear Mr. Randolph: This responds to your December 28, 1978, letter concerning an auxiliar fuel tank installed by the dealer on a 1978 Ford van that you purchased. You are concerned that the auxiliary tank represents a safety hazard due to the location of the tank's filler cap in the left rear wheel-well.; Federal Motor Vehicle Safety Standard No. 301-75, *Fuel Syste Integrity*, specifies performance requirements for fuel systems on motor vehicles. Although the standard applies to completed vehicles rather than to fuel tanks or other fuel system components, your dealer had to assure that your van complied with the standard. A person who mounts an auxiliary fuel tank on a new motor vehicle before the vehicle's first purchase in good faith for purposes other than resale is a vehicle alterer under National Highway Traffic Safety Administration regulations. That person is required by 49 CFR 567.7 to affix a label to the vehicle stating that, as altered, the vehicle conforms to all applicable Federal motor vehicle safety standards--including Safety Standard No. 301-75. Therefore, there should be an 'alterer' label on your van in addition to the certification label placed on the vehicle by the original manufacturer.; Even if the vehicle complies with Safety Standard No. 301-75, th location and design of the auxiliary fuel tank could constitute a safety-related defect for which the manufacturer would also be responsible. I am, therefore, forwarding a copy of your letter to the agency's Office of Defects Investigation. That office will examine this situation and may be in touch with you at a later date.; Thank you for your letter and for bringing this matter to ou attention.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam1868OpenMr. William Sousamian, Unique Truck Accessories, 10343 East Rush, South El Monte, CA 91733; Mr. William Sousamian Unique Truck Accessories 10343 East Rush South El Monte CA 91733; Dear Mr. Sousamian: This responds to your March 14, 1975, request for confirmation that mechanical parking brake device may be installed on air-braked trailers that were manufactured prior to January 1, 1975. We did not receive the literature you intended to enclose with your letter.; Standard No. 121 applies only to trailers manufactured after January 1 1975, and trucks and buses manufactured after March 1, 1975. The standard does not therefore, prevent the installation of a mechanical parking brake on trailers manufactured before January 1, 1975.; As for trailers manufactured in compliance with Standard No. 21, th standard does not prohibit the installation of a mechanical parking brake at the time of manufacture as long as the installation does not interfere with vehicle conformity. The mechancial (sic) device could also be installed after the first purchase of the trailer in good faith for purposes other than resale (i.e., the retail sale), as long as it does not involve the knowing disconnection of the 121-system by a manufacturer, distributor, dealer, or repair business.; Although you are no doubt aware of relevant Bureau of Motor Carrie Safety regulations, I have enclosed a copy of them for your information.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam2515OpenMr. B. R. Weber, Executive Vice President, Wesbar Corporation, Box 577, West Bend, WI 53095; Mr. B. R. Weber Executive Vice President Wesbar Corporation Box 577 West Bend WI 53095; Dear Mr. Weber: Thank you for your frank letter of January 13, 1977, commenting upo the lack of clarity you feel exists in my letter to you of December 6, 1976, interpreting Motor Vehicle Safety Standard No. 108.; As a lawyer it is obvious to me that the best regulatory practice is t be as specific as possible in establishing requirements and prohibitions. When a regulation itself is unclear, however, its interpretation may necessarily be imprecise. Because the term 'optical combination' in S4.4.1 is not defined, my answers were necessarily worded in general terms though with the thought of establishing a general framework of guidance for you. They were not intended to be 'a masterpiece of bureaucratic weasel words.' My letter meant, in plain English, that where tail lamps and clearance lamps are in a single compartment we don't want one lamp to perform, or to be perceived as performing, the function of the other. It is evident from your letter and others that our previous interpretations of the term 'optical combination' have been found to be ambiguous and lacking in the objective criteria that a Federal motor vehicle safety standard must provide. We have reviewed the matter, and now wish to modify our previous interpretation. In our view a lamp is 'optically combined' when the same light source (i.e. bulb) and the same lens area fulfill two or more functions (*e.g.* taillamp and stop lamp, clearance lamp and turn signal lamp). A dual filament bulb would be regarded as the 'same light source'. In determining conformance, the photometric requirements for clearance and taillamp functions, where two bulbs are located in a single compartment, must be met with only the bulb energized that is designed to perform the specific function. But the 15 candlepower maximum under Standard No. 108, however, would be determined with both the taillamp and clearance lamp bulb energized. Further, the lamp must be located to meet requirements for both clearance and taillamps. Our re- interpretation means that the issue of light spill-over from one area of the lamp to another is irrelevant to conformance.; Sincerely, Frank Berndt, Acting Chief Counsel |
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ID: aiam1977OpenMr. H. Ray Cozad, FMC Corporation, Crane & Excavator Division, 1201 Sixth Street Southwest, Cedar Rapids, IA 52406; Mr. H. Ray Cozad FMC Corporation Crane & Excavator Division 1201 Sixth Street Southwest Cedar Rapids IA 52406; Dear Mr. Cozad: This responds to FMC Corporations' June 23, 1975, request fo clarification of a recent NHTSA proposal (40 FR 24915, June 11, 1975) to amend Standard No. 121, *Air brake systems*, to establish an exemption criterion for a vehicle that has an 'unloaded vehicle weight that is not less than 95 percent of the vehicle GVWR gross vehicle weight rating '. You ask whether a vehicle's 'unloaded weight' means the GVWR, as established by adding the gross axle weight ratings (GAWR) of all axles, minus whatever portions of the vehicle are removed for highway travel.; The answer to your question is no. In light of the requirements fo GVWR in Part 567.4 (Certification), unloaded vehicle weight will normally be the GVWR of the vehicle minus its rated cargo load and its assigned occupant weight (at least 150 lbs). The rated cargo load would not include the weight of portions of a vehicle which are essential to its specialized function but are removed in accordance with State regulation for transit purposes.; I would also note that the NHTSA definition of GVWR (49 CFR S 571.3 does not require that the GVWR be the sum of the vehicle's GAWR's. Of course the GVWR must not exceed the sum of vehicle GAWR's.; With regard to your June 17, 1975, suggestion of a meeting with Mr Larson, I would prefer first to have your view of these clarifications.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam0098OpenMr. John W. Carlin, Calumet Corporation, P. O. Box 389, Kaukauna, WI 54130; Mr. John W. Carlin Calumet Corporation P. O. Box 389 Kaukauna WI 54130; Dear Mr. Carlin: Thank you for your letter of July 22, 1968, to Mr. George C. Nield concerning the applicability and effective date of Motor Vehicle Safety Standard 108.; Standard No. 108 is applicable to new vehicles manufactured on or afte the effective date of the standard. Initial Standard No. 108 was published on February 3, 1967, and became effective January 1, 1968. The initial standard is applicable only to vehicles that are 80 inches or more in overall width. Revised Standard No. 108 was published on December 16, 1967, and becomes effective January 1, 1969. The revised standard is applicable to passenger cars, multipurpose passenger vehicles, trucks, buses, trailers and motorcycles, regardless of overall width, however, the special requirements for vehicles that are 80 inches or more in overall width have been identified in the standard. Copies of the initial and revised standard are enclosed for your information.; In reply to your specific questions, information is provided a follows:; >>>1. With respect to your first question, Standard No. 108 i applicable to trailers manufactured for personal use by an individual and for commercial use.; 2. With respect to your second question, Revised Standard No. 108 effective January 1, 1969, specifies the lighting requirements for trailers that are less than 80 inches in overall width.; 3. With respect to your third question, the regulations of individua States and of the Bureau of Motor Carrier Safety (for vehicles engaged in interstate commerce) presently govern the lighting required on trailers that are less than 80 inches in overall width. Effective January 1, 1969, these trailers will be subject to the requirements of Revised Standard No. 108. Installation and location requirements for the individual lamps are contained in the referenced SAE standards (see Table III of Standard No. 108) and in Table IV of Standard No. 108.<<<; Also enclosed is a copy of the notice of 'Certification Requirement, which provides information on the manufacturer's certification of vehicles that are subject to the Federal motor vehicle safety standards.; Sincerely, Charles A. Baker, Office of Standards on Accident Avoidance Motor Vehicle Safety Performance Service; |
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ID: aiam3680OpenW.E.J. Moss, P. Eng., Flyer Industries Limited, 64 Hoka Street, Box 245 Transcona P.O., Winnipeg, Manitoba, Canada R2C 3T4; W.E.J. Moss P. Eng. Flyer Industries Limited 64 Hoka Street Box 245 Transcona P.O. Winnipeg Manitoba Canada R2C 3T4; Dear Mr. Moss: This responds to your January 27, 1983, letter asking about th application of Standard No. 217, *Bus Window Retention and Release*, to the front entrance doors of buses. You ask that the window retention test not be applied to your bus, because application of the required amount of force will cause the door to open. You state further that if the door had no glazing, it would not be tested for retention and, therefore, would be acceptable under the standard.; Standard No. 217 states that all glazing that exceeds 8 inches i diameter shall be tested for retention. During that test, neither the glazing nor the surrounding frame shall open in a manner that would allow a 4-inch sphere to pass through the opening. The intent of this requirements is of course to prevent the ejection of occupants in accidents.; The agency does test the front door of buses for compliance with thi section if they contain glazing that meets the size requirement. In tests that have been conducted, most front doors have complied. Accordingly, the proper construction of front doors in compliance with the requirement would not appear to be a problem. The agency does not believe that it would be in the interest of safety to exempt front door glazing from the test requirements. Although passengers are required to stand behind the standee line as you note in your letter, they may easily be thrown forward of that line in an accident. The agency considers it important to reduce the possibility of their being thrown from the vehicle if such a situation were to arise.; You are technically correct that an all metal door would not be teste for compliance with this retention provision since it would not contain glazing. However, the agency would not view favorably the installation of doors in buses that open so easily in an accident. Use of such doors might be considered to be a safety-related defect subject to the agency's recall and remedy authority.; Sincerely, Frank Berndt, 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.