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: 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: aiam1148OpenMr. Charles H. Sturgeon, Traffic Manager, Grove Manufacturing Company, Shady Grove, PA 17256; Mr. Charles H. Sturgeon Traffic Manager Grove Manufacturing Company Shady Grove PA 17256; Dear Mr. Sturgeon: This is in reply to your letter of April 23, 1973, requesting ou confirmation of certain issues discussed by you, and Michael Peskoe and David Fay of NHTSA, in a meeting in Mr. Peskoe's office on April 19, 1973.; It is correct that the NHTSA does not presently employ safet inspectors to inspect vehicles in service. Such inspections are made by inspectors of the Bureau of Motor Carrier Safety in the Federal Highway Administration, and it is true that their primary interest is the enforcement of the Bureau of Motor Carrier Safety regulations (49 CFR Parts 301-398). But if these investigators note violations of NHTSA regulations, the information will be forwarded to NHTSA and appropriate action will be taken.; It is correct that components of a vehicle in service may be added removed, or relocated at the discretion of a vehicle owner without violating NHTSA regulations. However, gross vehicle and axle weight ratings established by the vehicle manufacturer must be based on configurations of the vehicle which the manufacturer expects will be utilized in service. It is also correct that the weight imposed on each axle should not exceed the certified weight rating for each axle, but may be less than the certified weight rating.; Finally, it is correct that gross axle weight ratings may b established with a view towards the weight limitations of States in which the vehicle will be used.; Gross axle and vehicle weight ratings, under NHTSA regulations, ar manufacturers' figures, and may be set at any level as long as the figures are consistent with the limitations specified in the NHTSA certification regulations. However, the weight ratings must also, of course, be consistent with the vehicle's load-carrying capacity.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam3175OpenMr. Katsufumi Mitsui, General Manager, Industrial Textile Department, Toray Industries, Inc., 2-2, Nihonbashi-Muromachi, Chuo-ku, Tokyo, Japan; Mr. Katsufumi Mitsui General Manager Industrial Textile Department Toray Industries Inc. 2-2 Nihonbashi-Muromachi Chuo-ku Tokyo Japan; Dear Mr. Mitsui: This responds to a letter we received from Mitsui & Company askin questions concerning the 'resistance to light' test in paragraph S5.1(e) of Safety Standard No. 209, *Seat Belt Assemblies*, as it applies to polyester seat belt webbing. You asked whether it is true that this paragraph will not be enforced for dacron and polyester webbing until an appropriate test method can be incorporated in the standard, and whether such a test method is being developed.; In a July 23, 1976, letter to the Celanese Fibers Marketing Company th agency stated that the Standard No. 209 test procedure for resistance to light was developed to test nylon webbing and that the procedure does not give meaningful results for the new polyester webbings. Therefore, Celanese was informed that the requirement would not be enforced for polyester webbing until a new procedure could be developed. This letter was placed in our public docket for the benefit of all interested parties (in our 'Redbook' interpretations file). The agency does not intend to place an announcement of this interpretation in the *Federal Register*, however, since the standard will soon be amended to incorporate an appropriate test procedure for dacron and polyester webbing.; The new test procedure was developed for the National Highway Traffi Safety Administration by the Narrow Fabrics Institute and the Society of Automotive Engineers Task Force on Webbing. The new procedure would require the use of a plain glass filter instead of the Corex B filter currently required. The agency anticipates rulemaking to incorporate this new procedure sometime early next year, depending on rulemaking priorities.; I am enclosing a copy of our 1976 letter to Celanese for you information.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam1518OpenMr. W. G. Milby, Project Engineer, Blue Bird Body Company, P.O. Box 937, Fort Valley, GA, 81035; Mr. W. G. Milby Project Engineer Blue Bird Body Company P.O. Box 937 Fort Valley GA 81035; Dear Mr. Milby: In your letter of May 30, 1974, you ask whether a rear lightin configuration intended for your 1975 vehicles, based upon a proposal in Docket No. 69-19, would meet the current requirement that stop lamps be 'as far apart as possible.'; The photographs you enclose show that the intent of the proposed S8.1 has been met by providing a separation distance between turn signal and stop lamps that is 5 inches or more, and by placing the stop lamp so that its optical axis is inboard of a vertical longitudinal plane passing through the optical axis of the taillamps. Although it is obviously 'practicable' for you to retain the stop lamps in their present location, we consider that the reasons you wish to introduce the change support a determination of practicability under the current requirements, even though the proposal remains under consideration and may not be adopted.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam3525OpenMr. Leon W. Steenbock, Project Engineer, FWD Corporation, Clintonville, WI 52929; Mr. Leon W. Steenbock Project Engineer FWD Corporation Clintonville WI 52929; Dear Mr. Steenbock: This responds to your recent letter asking whether Safety Standard No 205, *Glazing Materials*, permits the use of Items 4 and 5 rigid plastics in rear windows on fire trucks. You were confused because the 'ANS Z26' standard permits rigid plastics in these locations, yet Standard 205 is silent on the issue.; The fact that Standard No. 205 does not specifically state that Items and 5 rigid plastics may be used in rear windows in trucks does not mean that such use is not permitted. The 'ANS Z26' standard is incorporated by reference in Standard No. 205 (paragraph S5.1.1). Therefore, glazing materials that conform with 'ANS Z26' may be used in the locations specified in that standard. In addition to the requirements and specified locations in 'ANS Z26,' Standard 205 includes other locations and requirements for additional types of glazing, as well as other locations for the Items of glazing that are specified in 'ANS Z26.'; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam3030OpenMr. Donald I. Reed, Director of Engineering, Trailer Manufacturer Association, 401 North Michigan Avenue, Chicago, IL 60611; Mr. Donald I. Reed Director of Engineering Trailer Manufacturer Association 401 North Michigan Avenue Chicago IL 60611; Dear Mr. Reed: This letter corrects an interpretation provided you on June 1, 1979. In our letter, we answered in the negative to your question whether: >>>'whether (sic) it is permissible to combine a clearance lam function in a tail lamp fixture if a second bulb is installed in the tail lamp which, when lit alone, satisfies the photometric requirements of the clearance lamp shown through the tail lamp lens ... and further assuming that all tail lamp photometric requirements are met when the tail lamp bulb alone is lit and when both lamps are lit.'<<<; We commented that such a lamp would appear to create the optica combination prohibited by S4.4.1 when both lamps are lit.; It has been brought to our attention that this conflicts wit interpretations provided on March 4, 1977, to Dennis Moore of Livermore, California, and B.R. Weber of West Bend, Wisconsin, both manufacturers of boat trailer lighting equipment. In our letter to Mr. Weber, for example, we interpreted 'optically combined' to mean a situation in which 'the same light source (i.e., bulb) and the same lens area fulfill two or more functions (i.e., tail lamp, and stop lamp, clearance lamp and turn signal lamp)'. The phrase is not intended to prohibit the installation of two separate bulbs in a single housing and covered by a common lens.; Upon review, we believe that the interpretation of March 4, 1977, i the correct one, and that the conflicting interpretation of June 1, 1979, should be with error. We are sorry for any confusion this may have caused your members.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam3460OpenMr. Charles Schamblin, Flag-It Signaling Device Co., P.O. Box 1709, Bakersfield, CA 93302; Mr. Charles Schamblin Flag-It Signaling Device Co. P.O. Box 1709 Bakersfield CA 93302; Dear Mr. Schamblin: The National Transportation Safety Board has forwarded for reply you letter of June 10, 1981, asking whether the 'Flag-It Automobile Signaling Device' would be legal to use according to your new regulations . . . .'; Requirements for equipment use are not established by the Federa government but by the individual State in which a vehicle is registered.; Our agency within the Department of Transportation establishes th Federal motor vehicle safety standards which apply to vehicle and equipment manufacturers. Your device consists of reflectors which hang beneath the front and rear bumper. They are not covered by our standard on reflectors (Standard No. 108 *Lamps, Reflective Devices and Associated Equipment*) nor would their installation appear to impair the effectiveness of lighting equipment required by Standard No. 108, which could raise a question as to their legality.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam2621OpenMr. Jack Gromer, Vice President - Technical Operations, Timpte, Inc., 5990 N. Washington Street, Denver, CO 80216; Mr. Jack Gromer Vice President - Technical Operations Timpte Inc. 5990 N. Washington Street Denver CO 80216; Dear Mr. Gromer: This responds to your May 6, 1977, letter asking whether your tir information label complies with the requirements of Standard No. 120, *Tire Selection and Rims for Motor Vehicles Other Than Passenger Cars, and Part 567, *Certification*. Further, you request that the National Highway Traffic Safety Administration (NHTSA) expedite treatment of Docket No. 73-31, Notice 1, which, if implemented would simplify the certification and information labels.; Concerning Docket 73- 31, the NHTSA published on June 20, 1977, notice (42 FR 31161) implementing Notice 1 which proposed the use of the designation 'all axles' rather than listing each axle individually on the certification label. The implementation of this regulation should resolve many of your problems.; Regarding the sample information label you submitted with your letter the NHTSA does not give advance approvals of compliance with Federal safety regulations or standards. We will, however, give an informal opinion of whether your label appears to comply with the requirements. The label you submitted does not appear to comply with the requirements of Part 567 or Standard No. 120. I have enclosed copies of both of these regulations for your information.; Your certification label should use the designation 'all axles' no 'each axle.' The tire and rim information should follow that designation stated in the form presented in the examples in Standard No. 120 and Part 567.; Sincerely, 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.