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: aiam3563OpenMr. Edward H. Clapp, President, Transquip Industries, Inc., 1222 RepublicBank Oak Cliff, Dallas, TX 75208; Mr. Edward H. Clapp President Transquip Industries Inc. 1222 RepublicBank Oak Cliff Dallas TX 75208; Dear Mr. Clapp:#This responds to your recent letter asking whethe Federal regulations allow a brake hose to be used as a dual purpose hose for both the service brakes and the emergency brake.#Standard No. 121, *Air Brake Systems*, does not preclude the use of common components in parking, emergency, and service air brake systems. Accordingly, nothing would prevent you from using a common hose in those systems. However, the common component would have to comply with the requirements for each system. This means that a failure of the hose would always be treated as a failure in the parking, emergency and service brake systems. Applying this to the standard in section S5.2.1.1, it would be necessary for the parking brakes to be capable of being released with a failure of the common hose at any time. If your system cannot perform in this manner, which it appears it cannot, it could not comply with the safety standard.#Our engineering staff has reviewed your brake system very carefully over the past years. It appears that your system can be properly plumbed in a manner that it would seem to comply with the requirements. You have continued to seek slightly less expensive methods to plumb your system. In our opinion, these methods would not be capable of complying with the standard. We cannot see how your system can comply with the standard without traditional plumbing that is being used by many brake manufacturers today. Accordingly, we suggest that you concentrate your efforts on constructing your system in that manner.#Sincerely, Frank Berndt, Chief Counsel; |
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ID: aiam3099OpenMr. Harry W. Reynolds, Supervisor, Fleet Maintenance Division, DeKalb County School System Service Center, 1780 Montreal Road, Tucker, GA 30084; Mr. Harry W. Reynolds Supervisor Fleet Maintenance Division DeKalb County School System Service Center 1780 Montreal Road Tucker GA 30084; Dear Mr. Reynolds:This responds to your July 27, 1979, letter whic asked whether any Federal law or regulations would prohibit the DeKalb County School System from converting the gasoline fuel systems in its school buses to propane fuel or dual propane- gasoline fuel systems. You specified that you would like this question answered both with respect to school buses manufactured in accordance with Federal Motor Vehicle Safety Standard No. 301- 75 and with respect to school buses manufactured before that standard's effective date. You also asked which persons may perform the conversions. As explained below, the laws administered by the National Highway Traffic Safety Administration (NHTSA) neither prohibit such a conversion of a school bus, regardless of whether it was initially manufactured in compliance with Safety Standard No. 301-75, nor specify which persons may perform such conversions.; Safety Standard No. 301- 75, *Fuel System Integrity*, promulgated b this agency pursuant to the National Traffic and Motor Vehicle Safety Act, as amended 1974 ('the Act') specifies performance requirements for the fuel systems of new motor vehicles, including school buses, which use fuel with a boiling point above 32 degrees F. (e.g., gasoline).; New vehicles, such as school buses, that have not yet been sold an delivered to a purchaser (here the school district) for purposes other than resale and that have been manufactured in compliance with Safety Standard No. 301-75 may be converted to propane and dual propane/gasoline systems. However, any person or entity, other than the purchaser, such as a manufacturer, dealer, or automobile repair business, who performs the conversion would be considered an alterer under NHTSA regulations.; An alterer is required to attach an additional label to the vehicl certifying that the vehicle, as altered, still complies with all applicable safety standards (49 CFR 567.7). Upon conversion of a new gasoline-powered school bus to a propane-powered school bus, Safety Standard No. 301-75 would cease to apply since propane has a boiling point below 32 degrees F. and the standard applies only to vehicles that use fuel with a higher boiling point. Therefore, the alterer would not be required to certify the school bus's continuing compliance with Safety Standard No. 301-75. However, upon conversion of a new gasoline-powered school bus to a dual powered school bus, Safety Standard No. 301-75 would remain applicable and the alterer would be required to certify the vehicle's continued compliance with that standard and all other applicable safety standards.; The installer of a propane or dual propane/gasoline system in a ne vehicle would be responsible for any safety related defects arising from the method of installation. The manufacturer of the system would be responsible for any safety related defects in the system itself. Thus, if a new school bus were found to contain a safety related defect following the addition of a new fuel system the installer or manufacturer, respectively, would be required to notify vehicle owners of any defects and to remedy these defects. (Sections 151 *et. seq.* of the Act, see enclosure). Also, please note if a propane or a dual propane/gasoline system were installed in a used school bus and was later found to contain any safety related defects, the manufacturer of the system would be responsible for notifying vehicle owners of the defect and for remedying them.; Used vehicles manufactured in accordance with Safety Standard No 301-75, as well as used vehicles manufactured before the effective date of that standard, may also be converted. Nothing in the Act prohibits a vehicle owner from modifying his own vehicles. Moreover, no law administered by the NHTSA prohibits other persons or entities such as manufacturers, distributors, dealers or motor vehicle repair business from modifying used vehicles.; This means that the DeKalb County School District would not b prohibited from converting its gasoline- powered buses, regardless of their date of manufacture, to propane or to dual-powered buses. It also means that if the school district sought to have the conversion done by a manufacturer, distributor, dealer or motor vehicle repair business, none of these persons or entities would be prohibited from doing the work.; However, such persons and entities could be subject to sectio 108(a)(2)(A) of the Act, if they converted used vehicles originally manufactured in compliance with Safety Standard No. 301-75. The section provides in relevant part 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 ....<<<; There is no liability under section 108(a)(2)(A) in connection wit Safety Standard No. 301-75, if one of the listed persons or entities converts a used gasoline-powered vehicle into a propane powered vehicle. Modification of the safety systems in a vehicle that is being converted from one vehicle type to another does not violate section 108(a)(2)(A) so long as the modified systems comply with the safety standards that would have been applicable to the vehicle had it been originally manufactured as the vehicle type to which it is being converted. For example, in converting a used gasoline-powered school bus (originally manufactured in compliance with Safety Standard No. 301-75) to a propane-powered school bus, the converter could not violate section 108(a)(2)(A) with respect to Safety Standard No. 301-75, since this standard, as noted earlier, does not apply to propane-powered school buses.; However, there could be liability under this section in connection wit Safety Standard No. 301-75 if, for example, one of the listed persons or entities converted a used gasoline- powered school bus (originally manufactured in compliance with Safety Standard No. 301-75) into a dual-powered school bus. In this situation, Safety Standard No. 301-75 would continue to apply to the school bus after the conversion. Thus, if in performing the conversion one of the compliance with Standard No. 301-75 while adding the propane system, that person or entity would have violated section 108(a)(2)(A).; I hope that you will find this response helpful. Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam3830OpenMr. Takeshi Tanuma, Chief Operating Office, Nissan Research & Development, Inc., P.O. Box 8650, Ann Arbor, MI 48104; Mr. Takeshi Tanuma Chief Operating Office Nissan Research & Development Inc. P.O. Box 8650 Ann Arbor MI 48104; Dear Mr. Tanuma: This responds to your April 4, 1984 letter regarding the use of tw certification labels on motor vehicles, with each label containing a portion of the information specified in 49 CFR Part 567 and the two labels together providing all the specified information.; While the certification regulations specify that 'a label' shall b used, the agency has permitted the use of a label in two parts in circumstances which will not lead to confusion and which will satisfy the basic intent of Part 567. In particular, the two portions of the label must be placed in close proximity to each other, to permit individuals to readily find all the specified information and to leave no doubt as to the significance of either portion of the label. Further, the two portions must be oriented in such a manner that the information specified in section 567.4(g) of the certification regulations appears in the required order. As a practical matter, these considerations require that the two portions be affixed to the same vehicle part. While we cannot specify a particular distance as a maximum permissible separation of the two portions of the label, the two portions must be located so as to leave the unmistakable impression that they provide related information.; You also raised the possibility of adding language to one portion o the label to indicate the existence of the other portion and to specify the location of the second portion. While such language is not required, it might be a desirable means of promoting compliance with the considerations discussed above.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam2722OpenMr. Philip H. Taft, Director, Tire Retreading Institute, National Tire Dealers & Retreaders Association, Inc., 1343 L Street, N.W., Washington, D.C. 20005; Mr. Philip H. Taft Director Tire Retreading Institute National Tire Dealers & Retreaders Association Inc. 1343 L Street N.W. Washington D.C. 20005; Dear Mr. Taft: This responds to your October 27, 1977, letter asking whether a tir retreader is permitted to change the designation of a tire from 'tubeless' to 'tubetype'.; Standard No. 117, *Retreaded Pneumatic Tires*, requires that th information appearing on the tire sidewall be the same as that which appeared on the tire as originally manufactured. This is indicated by the language in paragraph S6.3. If a retreader changed the tire designation from 'tubeless' to 'tubetype', he would be altering the information that was associated with the original tire. Thus, a retreader is not permitted to change the tire designation in the manner you describe.; Sincerely, Joseph J. Levin Jr., Chief Counsel |
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ID: aiam2372OpenMr. Don Dekker, Attwood Corporation, Lowell, MI, 49331; Mr. Don Dekker Attwood Corporation Lowell MI 49331; Dear Mr. Dekker: This is in response to your letter of June 23, 1976, in which you as whether Standard No. 302, *Flammability of Interior Materials*, applies to portable toilets.; Standard 302 applies to the motor vehicles listed in Section S3 including the equipment installed in them at the time of sale. Section S4 lists those parts of a motor vehicle that must comply with burn resistance requirements, and a portable toilet is not included. Therefore, it is not subject to the standard. I have enclosed a copy of the standard for your information.; Sincerely, Frank A. Berndt, Acting Chief Counsel |
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ID: aiam2688OpenMr. Dudley E. DeWitt, Assistant Director of Engineering, Great Dane Trailers, Inc., Lathrop Avenue, P.O. Box 67, Savannah, GA 31402; Mr. Dudley E. DeWitt Assistant Director of Engineering Great Dane Trailers Inc. Lathrop Avenue P.O. Box 67 Savannah GA 31402; Dear Mr. DeWitt: This responds to your July 8, 1977, letter posing several hypothetica questions concerning the responsibility to attach a new label to a vehicle if altered prior to first purchase for purposes other than resale.; Section 108(b)(1) of the National Traffic and Motor Vehicle Safety Act 15 U.S.C. 1397(b)(1), states that the prohibition against the delivery of a nonconforming vehicle 'shall not apply to the introduction or delivery for introduction in interstate commerce of any motor vehicle.....after the first purchase of it in good faith for purposes other than resale.' You ask at what point in time the 'first purchase' is deemed to have occurred. We have taken the position that the purchase is not complete until the vehicle is delivered to the purchaser.; In general, the issuance of title to which you refer in your letter i irrelevant to a determination of whether there is a need for the manufacturer's representative to attach a new label to an altered vehicle, as required by Part 567.7, *Certification*. Delivery of the vehicle is the point at which the first purchase is complete and the responsibility to attach a new label ceases. We would note that if the issue of vehicle modification is raised and decided upon during the sales conversations we would consider a subsequent modification occurring after the point of delivery to be an event requiring the attachment of a new label.; In particular response to your hypotheticals, paragraphs B and through H represent occasions when vehicle alterations would result in the need to attach a new label in accordance with the requirements of Part 567.7. The reason for this conclusion is that all of the hypotheticals result in the alteration of the gross vehicle weight rating (GVWR), or gross axle weight ratings (GAWR) or the attachment or removal of non-readily attachable components. There would be no need, in paragraphs B and D, to attach a new label if the vehicle manufacturer had availed himself of the option of listing alternative GAWR's, with appropriate tire sizes, as long as the newly installed tires were among those listed on the certification label.; Paragraphs A and C do not represent alteration situations in which th GVWR or the GAWR are affected. Although the tires would have a greater load capacity than that rated on the vehicle label, there is no need to change the rating of the vehicle, as is the case when tires are installed that have lower load capacities. Further, the installation of tires constitutes the installation of readily attachable components. Therefore, there is no need to attach a new label in accordance with Part 567.7 in these situations.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam5458OpenMr. Clay F. West Garvey, Schubert & Barer Eighteenth Floor Second & Seneca Building 1191 Second Avenue Seattle, WA 98101-2939; Mr. Clay F. West Garvey Schubert & Barer Eighteenth Floor Second & Seneca Building 1191 Second Avenue Seattle WA 98101-2939; Dear Mr. West: This responds to your letter of November 1, 1994 requesting information on any rules or standards applicable to a 'windshield cleaning device.' As your letter describes, '(t)he product is a clear strip which is adhered to the windshield of an automobile. The action of the wiper blades passing over the device causes the wiper blades to function more effectively.' I am enclosing a copy of a May 29, 1992 letter to Mr. John J. Jacoby concerning a similar device. I believe this letter contains the information you need. If you have any other questions, please contact Mary Versailles of my staff at this address or by phone at (202) 366-2992. Sincerely, Philip R. Recht Chief Counsel Enclosures; |
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ID: aiam3975OpenMr. K. Weight, 65 E. 200 N., Provo, UT 84601; Mr. K. Weight 65 E. 200 N. Provo UT 84601; Dear Mr. Weight: Thank you for your letter to Secretary Dole concerning black windows i automobiles. Your letter was referred to the National Highway Traffic Safety Administration since we are the agency that issues Federal Motor Vehicle Safety Standards (FMVSS). We have issued FMVSS No. 205, *Glazing Materials*, which sets performance requirements, including light transmittance requirements, for glazing used in motor vehicles. As explained below, FMVSS No. 205 limits the use of darkly tinted windows.; FMVSS No. 205 requires glazing, both tinted and untinted, in a ne passenger car to transmit at least 70 percent of the light that falls on it. To give you an idea of what level of tinting is allowed, please consider the following examples. If a window were completely open, the light transmitted through the opening would be 100 percent, clear windows have about 90 percent light transmittance, while factory-equipped tinted windows in new vehicles have about 80 percent light transmittance.; Minimum visibility levels are necessary to allow the average driver t detect other vehicles, pedestrians, bicyclists and traffic and road signs under all lighting conditions. Were the light transmittance *less* than 70 percent, such as found in darkly tinted glazing, visibility would be reduced to the extent that it could pose a safety hazard. From your description, I assume that the light transmittance of the 'black window' is less than 70 percent. A situation where the light transmittance is below 70 percent may be in violation of FMVSS No. 205.; No manufacturer or dealer is permitted to install tinting material i new vehicles without certifying that the vehicle continues to be in compliance with the light transmittance requirements of the standard. If a dealer, manufacturer, repair business or distributor installs dark tinting material in a used vehicle, then a violation of Section 108(a)(2)(A) of the National Traffic and Motor Vehicle Safety Act may result. That section provides that none of these persons may knowingly render inoperative any device or element of design installed on or in a motor vehicle or item of motor vehicle equipment in compliance with an applicable motor vehicle safety standard. Violation of the 'render inoperative' provision can result in Federal civil penalties of up to $1,000 for each violation.; Owners of used vehicles may, themselves, alter their vehicles, so lon as the vehicle adheres to all State requirements. Under Federal law, the owner may in this manner install dark tinting material regardless of whether the installation adversely affects the light transmittance. Individual States govern the operational use of vehicles by their owners and therefore it is within the authority of the States to preclude owners from applying dark tinting material on their vehicles.; I hope this information is helpful to you. Sincerely, Jeffrey R. Miller, Chief Counsel |
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ID: aiam1948OpenS. L. Terry, Vice President, Public Responsibility and Consumer Affairs, Chrysler Corporation, P.O. Box 1910, Detroit, MI 48231; S. L. Terry Vice President Public Responsibility and Consumer Affairs Chrysler Corporation P.O. Box 1910 Detroit MI 48231; Dear Mr. Terry: This responds to your letter of May 13, 1975, requesting confirmatio that Chrysler's new unibelt shoulder/lap belt system with a 'window shade' tension adjustment feature satisfies the requirements of S7.1.1 of Standard No. 208, Occupant Crash Protection, that the lap belt portion 'adjust by means of an emergency-locking or automatic-locking retractor.' You describe the seat belt assembly as of the single retractor, continuous loop type, with a B-pillar-mounted 'window shade' emergency-locking retractor, and a one-way locking device in the buckle tip which prevents return of webbing to the lap portion from the torso portion when the belt assembly is in use.; Section 7.1.1 requires adjustment of the lap belt portion 'by means o an emergency-locking or automatic-locking retractor' and adjustment in most cases of the upper torso portion 'by means of an emergency-locking retractor.' The language permits some single refractor, continuous loop systems as long as the single retractor does 'automatically adjust' the tension of the lap belt portion to prevent excessive belt slack. Because of the submarining danger of a slack lap belt, the NHTSA has restricted the acceptability of continuous loop systems under S7.1.1 in two areas.; One restriction, set forth in a letter to Renault, Inc., on Septembe 25, 1972, is that 'the friction in the buckle is low enough that the normal motion of the occupant against the shoulder belt cinches up the lap belt.'; We would like to clarify that letter by emphasizing that, to conform t the requirements, the assembly must be designed by the manufacturer with a sufficiently low level of friction to qualify the lap portion as 'automatically adjustable.' Thus, it is the manufacturer who determines whether or not the particular belt is designed to satisfy the requirements of the standard. In your May 16, 1975, demonstration to Messrs. Hitchcock, Nelson, Medlin, Smith, Breedon, and Ziegler of the NHTSA, we saw no evidence of design deficiency in limited use of that continuous loop system.; The other restriction was set out in a March 9, 1973, letter to Genera Motors. It limits the use of 'comfort clips' on the upper torso portion of continuous loop systems. The letter distinguishes continuous loop systems from systems that have separate lap and shoulder belt retractors. It concludes that 'a comfort clip would be acceptable under S7.1.1 of the standard, so long as the shoulder belt is otherwise capable of adjustment as required by S7.1.1.'; This restriction has since been the subject of an NHTSA proposa (Docket 74-32, Notice 1) which would restrict the use of 'a device used to limit retractive action of an emergency-locking retractor for the comfort of the occupant' to seat belt assemblies that have 'an individually adjustable lap belt.' Chrysler's response to that proposal and stated plan to introduce a continuous loop belt system with a 'window shade' device in the new 1976 model four-door compact car assume that NHTSA intends to permit 'belt tension relief' devices on all continuous loop systems. I would like to point out that this issue is outstanding in Docket 74-32.; Sincerely, James B. Gregory, Administrator |
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ID: aiam2667OpenMessrs. George Schwarz and T. Szkolniki, Supervisors, Production and Mechanical Engineering, Motor Coach Industries, Inc., Pembina, ND 58271; Messrs. George Schwarz and T. Szkolniki Supervisors Production and Mechanical Engineering Motor Coach Industries Inc. Pembina ND 58271; Gentlemen: This will acknowledge receipt of the petition by Motor Coac Industries, dated July 22, 1977, for a determination that an apparent noncompliance with Motor Vehicle Safety Standard No. 121 is inconsequential as it relates to motor vehicle safety.; We are preparing a notice for publication in the *Federal Register requesting public comment on your petition and you will be notified in due course as to its disposition. The notice will not include reference to the fact that the 'continuous warning' signal required by S5.1.5 of Standard No. 121 is an automatic flashing light on MCI vehicles. It is the opinion of this office that either an automatic flashing light or a continuous light will provide a 'continuous warning' within the intent of the Standard.; Yours truly, Joseph J. Levin, Jr., Chief Counsel |
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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.