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
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ID: aiam1852OpenMr. J. M. Dabrowski, Vice President-Engineering, The Flxible Co., Loudonville, OH 44842; Mr. J. M. Dabrowski Vice President-Engineering The Flxible Co. Loudonville OH 44842; Dear Mr. Dabrowski: This is in response to your letter of February 10, 1975, inquiring a to the effect of Federal Motor Vehicle Safety Standard No. 121 on State laws relating to air brake performance.; Section 103(d) of the National Traffic and Motor Vehicle Safety Act o 1966 (15 U.S.C. 1392(d)) provides that no State or political subdivision of a State may promulgate or continue in effect standards applicable to an aspect of motor vehicle or motor vehicle equipment performance which is covered by a Federal motor vehicle safety standard, unless the standards are identical.; Standard No. 121 includes provisions relating to truck and bus brak performance, including requirements for stopping distances. A more restrictive State brake requirement than that specified in Standard 121 is voided by S 103(d) since the Federal standard is intended to cover all aspects of air brake performance.; The Federal requirements must be regarded as conclusive with regard t emergency braking capabilities in order to maintain the uniformity necessary in a Federal regulatory scheme. This was affirmed in a recent decision rendered in a case brought by the Motorcycle Industry Council, Inc. against the State of California in the United States District Court for the Eastern District of California concerning the preemption of a California State requirement that motorcycle headlamps be wired to operate when the engine is running. The Court held that the California requirement is preempted by the Federal Motor Vehicle Safety Standard No. 108 since the NHTSA intended to cover all aspects of performance directly involving motorcycle headlamps.; Therefore, requirements such as those described in your letter would b preempted by Standard 121 since the aspects of performance that would be affected are covered by the Federal standard. You should note that this discussion of State 'requirements' only refers to rules of general applicability within a State or municipality. It does not refer to purchase specifications that may be imposed by any person or organization, including a State or municipality, with respect to vehicles purchased for the person or organization's own use. Such specifications are not limited by Federal law, although of course they cannot alter a manufacturer's duty to conform to Federal standards.; I would note that your statement that neither S5.7.2 nor S5.7.2. 'requires anything other than an application capability' is overbroad. Section S5.7.2 requires modulation of the emergency braking capability, that is, application and release. We have interpreted the S5.7.2.2 requirement that emergency brake system failure 'shall not cause the parking brake to be inoperable' to mean that the parking brake must be capable of application but not release. Under S5.6 the parking brake's normal operation must include both application and release.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam5112OpenMr. Guy Boudreault 340 7th Avenue, #1 Ile Perrot, P.Q. J7V 4T6 CANADA; Mr. Guy Boudreault 340 7th Avenue #1 Ile Perrot P.Q. J7V 4T6 CANADA; Dear Mr. Boudreault: This responds to your letter expressing concern about certain working conditions that you have experienced as a driver of a commercial vehicle, and asking about rules and regulations that apply to the adjustment of brakes on commercial vehicles. I am pleased to have this opportunity to respond to you. By way of background information, this agency, the National Highway Traffic Safety Administration, is authorized by the National Traffic and Motor Vehicle Safety Act to issue Federal motor vehicle safety standards applicable to new motor vehicles and motor vehicle equipment. We have issued a number of safety standards that apply to heavy vehicles, including ones on brakes and lighting. This agency does not have the authority to regulate the use of motor vehicles. Your letter concerns in-service safety requirements for commercial vehicles and drivers, rather than safety requirements that apply to new motor vehicles. Within the U.S. Department of Transportation, the Federal Highway Administration, Office of Motor Carriers, has the authority to issue motor carrier safety regulations for interstate motor carriers and drivers. Ordinarily I would refer your letter to that agency, however, your letter indicates that you sent the same letter to the Office of Motor Carriers as you sent to this agency. I hope this information is helpful. If you have any questions about NHTSA's safety standards, please feel free to contact Marvin Shaw of my staff at this address or by telephone at (202) 366-2992. Sincerely, Paul Jackson Rice Chief Counsel; |
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ID: aiam0310OpenMr. Tom Caine, Attorney, Goodyear Tire and Rubber Company, Akron, OH 44316; Mr. Tom Caine Attorney Goodyear Tire and Rubber Company Akron OH 44316; Dear Mr. Caine: This is in reply to your letters of February 9 and February 17, 1971 requesting a clarification of the applicability of Part 574, the Tire Identification and Record Keeping regulation, to changeover tires.; In your letters you suggest that, for purposes of Part 574, changeove tires should be considered as used tires, because (1) as a legal matter title to both the vehicle at the time of purchase, (2) tire dealers generally accept changeover tires with less than 100 miles of use as trade-in tires, (3) changeover tires are considered to be used tires by the Federal Trade Commission, and (4) in most cases the tire manufacturer will not have direct contact with the tire dealer selling the changeover tires after they have been traded in by the vehicle purchaser.; We have carefully considered these points, and have determined tha Part 574 is nevertheless applicable to changeover tires.; Part 574 is an integral part of the enforcement scheme for complianc with the standards and the requirements with respect to safety-related defects, and as such its coverage is intended to be coextensive with the applicability of the standards. Section 108(a) of the National Traffic and Motor Vehicle Safety Act prohibits the manufacture for sale, sale, or offering for sale of tires which do not conform to applicable standards. Although the Act provides that this prohibition shall not apply after the first purchase, it specifically limits this exemption to purchases made 'in good faith for purposes other than resale.' Therefore, the fact that title to original-equipment tires has passed to the vehicle purchaser is not controlling, because in these cases the purchaser intends to exchange the tires--that is, he is purchasing them for the purpose of reselling them, not for using them.; If the standard were not applicable to changeover tires, tire dealer could with impunity alter these tires in a manner that would make them unsafe. A case in point is the known practice whereby dealers alter the sidewalls of tires, often changeover tires, by cutting out a groove and laminating a whitewall surface to the surface of the tire.; Another policy reason for applying Part 574 to changeover tires i that, from a safety standpoint, the person who actually is using the changeover tires on his vehicle should be the one who is notified in the event the tires are suspected of being defective.; We recognize that the Federal Trade Commission does not allo changeover tires to be sold as new tires. That agency is, however, primarily concerned with fraudulent sales, an area of concern much different from ours. The difference in the definitional categories used by the two agencies is, we feel, fully justified by their different missions.; With regard to your point that the manufacturer of the changeover tire would not have direct contact with the dealer who sells the changeover tires, I will simply say that this is true in many situations with regard to tire distribution, and we do not consider it sufficient grounds to make the regulation inapplicable to changeover tires. It does not appear to be an undue hardship for a tire dealer to obtain a form and forward the information concerning the purchaser of the tire to the tire manufacturer.; Sincerely, Lawrence R. Schneider, Acting Chief Counsel |
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ID: aiam2907OpenMr. W. G. Milby, Manager, Engineering Services, Blue Bird Body Company, P. O. Box 937, Fort Valley, GA (sic); Mr. W. G. Milby Manager Engineering Services Blue Bird Body Company P. O. Box 937 Fort Valley GA (sic); Dear Mr. Milby: This responds to your September 20, 1978, letter asking whether particular bus body joint is subject to the requirements of Standard No. 221, *School Bus Body Joint Strength*. The joint in question is the connection of two body panels under which runs a continuous body member for the entire length of the bus body.; Standard No. 221 establishes strength requirements for body pane joints which are defined as 'the area of contact or close proximity between the edges of a body panel and another body component...' Body panel is further defined to mean 'a body component used on the exterior or interior surface to enclose the bus' occupant space.' The exterior body panels to which you refer are involved in the enclosure of the bus' occupant space, and accordingly, their connection is a joint falling within the requirements of the standard. The fact that an underlying body member runs under the panels perpendicular to the joint in no way excepts the joint from the requirements of the standard.; Your analogy of these panels to rub rails whose joints are not teste according to the requirements of the standard is inappropriate. Rub rails are added on to the exterior of a bus over the body panels. All parts of the rub rails fall outside the exterior skin of a bus, and therefore, they serve no purpose in enclosing occupant space. The panels to which you refer, on the other hand, are the primary sidewall components enclosing bus' occupant space.; You ask how the agency will test this joint since it has a bod structure member that runs perpendicular to it. You suggest that the agency cut an appropriate size specimen of the panels, joint, and underlying body member and pull one panel and the body member against the other panel and the body member. The agency disagrees. This procedure would not test the strength of the joint, since the stresses imposed by the test would be carried by the continuous body member being pulled against itself.; The agency tests such joints by cutting a specimen of the panels tha includes a portion of the underlying body member. The ends of the body member are then removed to allow the testing device to clamp the two body panels that are to be tested. However, rivets or other bonding materials that connect the panels and the body member at the joint remain intact. This is what is intended by the standard's requirement that the underlying body structure be included within the joint strength test. Leaving the underlying structure intact at the joint permits a test of the joint's strength that closely approximates the actual strength of the joint as it is installed in a completed bus.; Responding finally to your last comment that the agency by its testin technique is hindering the development of integrally constructed bodies, the NHTSA disagrees. The agency believes that the strength of the entire bus body is dependent upon the strength of its parts. Each joint must be examined independently to ensure that it is strong enough to withstand accident forces. Since those forces vary with the nature of any impact and can result in severe stress on one small section of a bus, it is appropriate to measure the strength of individual joints. However, the agency's testing technique as outlined above considers the effect of the underlying bus structure thus encouraging the development of integrally constructed bodies.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam3615OpenMr. Lawrence T. Hirohata, Vehicle Equipment Safety Specialist, Department of Transportation, State of Hawaii, 79 South Nimitz Highway, Honolulu, HI 96813; Mr. Lawrence T. Hirohata Vehicle Equipment Safety Specialist Department of Transportation State of Hawaii 79 South Nimitz Highway Honolulu HI 96813; Dear Mr. Hirohata: This responds to your recent letter asking whether persons who appl tinted films to motor vehicle glazing would be considered motor vehicle distributors, dealers or repair businesses and thus be prohibited by section 108(a)(2)(A) of the National Traffic and Motor Vehicle Safety Act from rendering inoperative components that have been installed on vehicles pursuant to Federal Motor Vehicle Safety Standards.; The answer to your question is yes. The persons you described fal within classes of persons listed in section 108(a)(2)(A) and the application of tinted film to motor vehicle glazing can constitute rendering inoperative.' Section 108(a)(2)(A) of the Safety Act provides that:; >>> No manufacturer, distributor, dealer, or motor vehicle repai business shall knowingly render inoperative, in whole or part, any device or element of design installed on or in a motor vehicle or item of motor vehicle equipment in compliance with an applicable Federal motor vehicle safety standard,....For purposes of this paragraph, the term motor vehicle repair business' means any person who holds himself out to the public as in the business of repairing motor vehicles or motor vehicle equipment for compensation.'<<<; Without knowing more about the film appliers you described, we find i difficult to determine the number of classes into which they would fall. However, the film-appliers are clearly considered to be dealers. This conclusion is based on the definitions of motor vehicle equipment' (section 102(4)), and dealer' (section 102(7)). The tinted film is an item of motor vehicle equipment since it is an accessory, or addition to the motor vehicle.' Therefore, any person who sells the tinted film primarily to persons, typically vehicle owners, for purposes other than resale is a dealer. The status of such a person does not change because he or she also applies the film to motor vehicle glazing.; The film appliers you described may also be motor vehicle repai businesses. You stated that the film appliers argue that they are not repair businesses. Implicit in their argument is a narrow interpretation of the term repair.' We don't believe that such an interpretation was intended by Congress since it would frustrate Congress' stated purpose in attempting to ensure that safety equipment remains operative over the life of the vehicle. The only type of person mentioned in the legislative history as being permitted to render safety equipment inoperative is the owner of the vehicle on which the safety equipment is installed. In addition, we believe that the references in the history to service, maintenance and replacement further suggest that a narrow interpretation was not intended.; The agency has consistently stated in its past letters o interpretation that the installation of tinted films on vehicle glazing constitutes rendering inoperative if the installation destroys the glazing's compliance with the light transmittance requirements of Safety Standard No. 205. The legislative history of section 108(a)(2)(A) provides that render inoperative' includes permanent removal, disconnection or *degradation* of the safety performance of any element or design of a vehicle (Conference Report). Therefore, the activity described in your letter definitely falls within the scope of section 108(a)(2)(A).; In conclusion, it is the agency's opinion that businesses which ar installing tinted films on motor vehicles and thereby destroying the glazing's compliance with the light transmittance requirements of Safety Standard No. 205 are in violation of section 108(a)(2)(A) of the National Traffic and Motor Vehicle Safety Act. As such, the businesses are liable for civil penalties up to $1,000 for each violation.; Our Office of Enforcement is currently investigating the practice o applying tinted film to motor vehicle glazing. Accordingly, we have forwarded a copy of your letter and the advertisement to that office for its action.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam1628OpenMr. H. Hirai, Technical Representative, Toyo Kogyo Co., Ltd., 23777 Greenfield Rd. Suite 462, Southfield, MI 48075; Mr. H. Hirai Technical Representative Toyo Kogyo Co. Ltd. 23777 Greenfield Rd. Suite 462 Southfield MI 48075; Dear Mr. Hirai: This responds to Toyo Kogyo's October 2, 1974, question whether 'cur weight' includes only the weight of an air conditioner installed by the manufacturer at the factory, or whether it also includes the weight of an air conditioner installed by a Toyo Kogyo dealer prior to sale of the vehicle.; 'Curb weight' is defined in 49 CFR S571.3 as 'the weight of a moto vehicle with standard equipment, maximum capacity of engine fuel, oil, and coolant, and, if so equipped, air conditioning and additional weight optional engine.'; Section 108(a) (1) of the National Traffic and Motor Vehicle Safety Ac of 1966 requires that a vehicle comply with applicable Federal motor vehicle safety standards at the time of sale. Therefore, a vehicle must be capable of meeting a standard's requirements with the weight of any air conditioner that is present in the vehicle at the time of its sale, if the weight specified for compliance testing includes an air conditioning system.; We understand that your question arises with regard to the prope vehicle loading to conduct a barrier crash test under Standard No. 204, *Steering control rearward displacement*. Neither Standard No. 204 nor the SAE procedures it references, specifies vehicle weight conditions for purposes of the crash test. In the absence of a weight specification, the NHTSA concludes that the vehicle must be capable of meeting the requirement with the weight of the air conditioner included, if the vehicle is to be so equipped at the time of its sale.; As it interprets the Safety Act of 1966, the NHTSA has established th policy that a manufacturer may conduct certification testing in any manner it chooses, as long as it is calculated, in the exercise of due care, to demonstrate that the vehicle would pass if tested as specified in the standard. Thus, Toyo Kogyo could, for example, choose the air conditioner installation most adverse to barrier testing and conduct its barrier crash test with that air conditioner installed. Such testing would be evidence that the vehicle is capable of meeting the requirement with any other air conditioner installed, including the factory air conditioner.; Yours truly, Richard B. Dyson, Acting Chief Counsel |
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ID: aiam0890OpenMr. Olav Kviteng, A/S Raufoss Ammunisjonsfabrikker, 2831 Raufoss, Norway; Mr. Olav Kviteng A/S Raufoss Ammunisjonsfabrikker 2831 Raufoss Norway; Dear Mr. Kviteng: This is in reply to your letter to the Docket Section of September 28 1972, on the subject of the test speeds required for the corner impact tests of Motor Vehicle Safety Standard No. 215, Exterior Protection.; The correct impact speed in corner tests is 3 m.p.h. at both front an rear. The test speed was reduced to this level by a notice of rulemaking published June 22, 1972, and has not been subsequently changed. The publication sent you by the Government Printing Office, in which the speed is erroneously given as 5 m.p.h. for the front and 4 m.p.h. for the rear, is not an official publication and does not affect the requirement.; We regret the error. The test speed will be corrected in futur supplements.; Truly yours, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam1782OpenMr. J.R. Farron,Bendix Corp.,P.O. Box 4001,South Bend, Indiana 46634; Mr. J.R. Farron Bendix Corp. P.O. Box 4001 South Bend Indiana 46634; Dear Mr. Farron:#Please forgive the delay in responding to your lette of November 8, 1974, concerning Federal Motor Vehicle Safety Standard No. 106-74, *Brake Hoses*.#In our letter of July 8, 1974, We explained that a neoprene connector, which you now designate as the Hydrovac Vacuum Connector, is included under the definition of 'brake hose,' set out in the standard, because it is flexible. Your letter of November 8, 1974, suggested that, due to the nature of the connector's installation, it is not subject to the usual hazards associated with the flexibility of brake hose. The connector is nevertheless a 'flexible conduit manufactured for use in a brake system to transmit or contain the fluid pressure or vacuum used to apply force to a vehicle's brakes,' and so cannot be excluded from the definition of 'brake hose' without further rulemaking activity. We are considering the possibility of an amendment of the definition to exclude this type of connector from the coverage of Standard No. 106-74. any such proposal would be published in the Federal Register.#Yours truly,James C. Schultz,Chief Counsel; |
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ID: aiam3245OpenMr. John B. Galotti, Service Manager, Sholz Oldsmobile, 35 West Post Road, White Plains, NY 10606; Mr. John B. Galotti Service Manager Sholz Oldsmobile 35 West Post Road White Plains NY 10606; Dear Mr. Galotti: This responds to your recent letter requesting information concernin the legal requirements applicable to the installation of fuel separators and auxiliary fuel tanks in motor vehicles. I am enclosing a copy of a letter the agency issued last year which discusses the Federal requirements and implications that would be involved with such activities. That discussion should answer all of your questions. If, however, you require further information, please contact Hugh Oates of my office at 202-426-2992.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam1278OpenMr. Donald Gary Hayes, Robertson Tank Lines Inc., P. O. Box 1505, Houston, TX 77001; Mr. Donald Gary Hayes Robertson Tank Lines Inc. P. O. Box 1505 Houston TX 77001; Dear Mr. Hayes: This is in reply to your letter of August 30, 1973, requesting a DO code number for retreaded tires you manufacture. It appears from your letter that the tires you retread are truck tires intended solely for your company's own use.; Any tires retreaded by and solely for use by Robertson Tank Lines ar exempt from NHTSA recordkeeping requirements and a code number is not required. As truck retreads are not subject to any Federal motor vehicle safety standard, you are also not required to place a 'DOT' symbol on them. If you retread passenger car tires, however, you are required to place a 'DOT' symbol on the tire sidewall (indicating conformity to Federal Motor Vehicle Safety Standard No. 117).; 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.