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: aiam3060OpenMr. Donald Beyer, National Service Manager, Vespa of America Corporation, 355 Valley Drive, Brisbane, CA 94005; Mr. Donald Beyer National Service Manager Vespa of America Corporation 355 Valley Drive Brisbane CA 94005; Dear Mr. Beyer: This is in reply to your letter of June 20, 1979, asking for a interpretation of Federal Motor Vehicle Safety Standard No. 108 as it relates to operation of turn signal lamps by alternating current. You have informed us that Vespa wishes to use such a system on its 1980 motor driven cycles, and you have asked what SAE Standard or method must be followed by the lamps to comply.; Table III of Standard No. 108 requires that any motor driven cycles whose speed attainable in 1 mile exceeds 30 mph, be equipped with a turn signal flasher meeting SAE Standard J590b, *Turn Signal Flasher*, October 1965. The scope of this SAE Standard is that the specifications 'are for nominal 12 or 6 v - dc circuits ....' We construe this to mean that the typical electrical system of a motorcycle is designed to utilize direct current (dc), so that the alternate current (ac) flow from the alternator must be rectified (changed) to dc.; We would have no objections, however, to a turn signal system fed b alternating current if Vespa could demonstrate that such turn signal flashers and lamps would meet all performance requirements of SAE Standard J590b, *Turn Signal Flashers*, as well as the other requirements set forth in Standard No. 108.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam2221OpenMr. Robert C. Yates, President, Local 178, United Rubber, Cork, Linoleum and Plastic Workers of America, 2209 West Riverview Avenue, Dayton, OH 45407; Mr. Robert C. Yates President Local 178 United Rubber Cork Linoleum and Plastic Workers of America 2209 West Riverview Avenue Dayton OH 45407; Dear Mr. Yates: Your letter of December 1, 1975, to the Federal Trade Commission concerning the dates molded into tires manufactured by the Dayton Tire and Rubber Company, has been forwarded to this agency for further reply.; Motor Vehicle tires are required by S 574.5 of 49 CFR Part 574, *Tir Identification and Recordkeeping*, to be labeled with an identification number containing certain information. A copy of this regulation is enclosed for your convenience. The last three digits of this number indicate the week and year of manufacture of the tire, as follows: the final digit is the last digit of the year, and the preceding two digits represent the week within that year. The numbering of the weeks begins with '01' for the first full calendar week in each year. For example, '016' indicates that a tire was manufactured during the week beginning Sunday, January 4, 1976, and ending Saturday, January 10. While the precise labeling on the tires that you have described is not clear from your letter, it appears that some of the tires do not comply with this labeling requirement, because November 24 and December 1 were not in the same calendar week of 1975.; I have forwarded a copy of your letter to our Office of Standard Enforcement for such further action as may be appropriate.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam2671OpenMr. Ray Sizemore, Crane Carrier Company, 1925 N. Sheridan, P.O. Box 51191, Tulsa, OK 74151; Mr. Ray Sizemore Crane Carrier Company 1925 N. Sheridan P.O. Box 51191 Tulsa OK 74151; Dear Mr. Sizemore: This responds to Crane Carrier Corporation's June 8, 1977, questio whether the maximum time limits specified by S5.1.1 of Standard No. 121, *Air Brake Systems*, for build-up of brake system air pressure from 85 to 100 psi includes the time taken to build up air pressure in an accessory reservoir (for an air starter) that is replenished only when the truck is started.; The answer to your question is no. Section S5.1.1 is a performanc requirement that assures that repeated use of the brakes during vehicle operation will not deplete the available air supply because of insufficient air compressor capacity. The purpose of this requirement only indirectly relates to the initial air pressure build-up that occurs when the vehicle is first started.; The agency's existing laboratory procedure for compliance testin provides for fully charging the air brake system (and any accessory reservoirs which charge automatically in the process) before the test is begun. The engine is shut off while brake system air pressure is reduced to a level that permits a subsequent build-up for measurement purposes. In order to properly test vehicles with air starters, the agency is modifying its procedure to keep the engine running throughout the test, so that the air starter reservoir remains fully charged throughout the measurement period.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam3963OpenMr. Don Benfield, Sales Manager, Express Yourself Company', P.O. Box 2357, Anderson, IN 46018; Mr. Don Benfield Sales Manager Express Yourself Company' P.O. Box 2357 Anderson IN 46018; Dear Mr. Benfield: Thank you for your letter of April 12, 1985, concerning stat regulations that might affect a product you are considering. You explained that your product would fit inside the rear window of a vehicle. While we do not have information on state laws, I can explain the possible effect of Federal law on your potential product. I suggest you contact vehicle safety officials in the states in which you plan to sell your product to learn of their laws.; The National Traffic and Motor Vehicle Safety Act authorizes our agenc to issue Federal Motor Vehicle Safety Standards that apply to new motor vehicles and items of motor vehicle equipment. The agency has issued Federal Motor Safety Standard No. 205, *Glazing Materials*, which sets performance requirements for glazing materials used in new motor vehicles and glazing materials sold as items of replacement equipment, a copy of the standard is enclosed. If your product is mounted on, rather than inside, the rear window, it could be affected by Standard No. 205.; The performance requirements of the standard include ones regulatin the light transmittance and abrasion resistance of glazing. Manufacturers of new vehicles must certify that the glazing in windows requisite for driving visibility conforms with the light transmittance and other requirements of the standard. If a manufacturer or dealer places your product on the rear window in a new vehicle prior to the sale of the vehicle, that person must certify that the glazing continues to be in compliance with the requirements of Standard No. 205.; In 1974, Congress amended the National Traffic and Motor Vehicle Safet Act to address the problems of persons tampering with safety equipment installed on a motor vehicle by adding section 108(a)(2)(A) to the Act. That section provides, in 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 safety standard....<<<; Thus no manufacturer, distributor, dealer, or motor vehicle repai business may add material to the glazing materials of a motor vehicle, if that material would render inoperative the glazing's compliance with Standard No. 205.; Section 108(a)(2)(A) does not establish any limitations on a individual vehicle owner's ability to alter his or her own vehicle. Under Federal law, individual vehicle owners can themselves install any material they want on their vehicles, regardless of whether that material would render inoperative the compliance of the vehicle's glazing with the performance requirements of Standard No. 205.; If your product is not mounted on the window itself, it still may b affected by our standards. Standard No. 111, *Rearview Mirrors*, sets performance requirements for rearview mirrors, a copy of the standard is enclosed. The standard provides that each inside rearview mirror must provide a specified field of view to the rear of the vehicle. If the field of view of the inside mirror in a new vehicle is obstructed by anything other than head restraints or seated occupants, then an outside rearview mirror must be provided on the passenger's side of the vehicle.; Thus, if your product were mounted inside the rear window of a ne vehicle by a manufacturer or dealer at the time of its sale, and if installation of your product would mean that the inside rearview mirror would no longer comply with the applicable field of view requirements, they would have to ensure the vehicle was equipped with the necessary additional mirror required by Standard 111. Just as with Standard No. 205, section 108(a)(2)(A) would apply to the installation of your product in used vehicles by manufacturers, distributors, dealers, and motor vehicle repair shops. Thus, if your product is mounted inside the rear window and its installation would mean that the inside rearview mirror would no longer comply with the applicable field of view requirements, an outside passenger side mirror would have to be installed. Again, section 108(a)(2)(A) does not limit the actions of individual vehicle owners.; If you have further questions, please let me know. Sincerely, Jeffrey R. Miller, Chief Counsel |
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ID: aiam3349OpenMr. William Blythe, 1545 University Avenue, Palo Alto, CA 94301; Mr. William Blythe 1545 University Avenue Palo Alto CA 94301; Dear Mr. Blythe: This responds to your recent letter asking questions concerning th test procedures of Safety Standard No. 216, *Roof Crush Resistance* (49 CFR 571.216). Specifically, you are concerned with the proper applications of the test block forces specified in paragraphs S6.3 and S6.2(d) of the standard.; Your first question asks whether paragraph S6.3 allows the force on th test block to be applied 'essentially opposite the initial contact point of the roof to the block.' Paragraph S6.3 specifies that the force required by the standard shall be applied in a downward direction to the lower surface of the test device. Figure 1 of the standard illustrates this procedure and indicates that the force is to be centrally applied to the loading block. This procedure will be followed during tests by the agency to determine the compliance of particular passenger cars with Safety Standard No. 216. Therefore, we would not recommend that you apply the force opposite the initial contact point of the test block with the roof.; Paragraph S6.2(d) of the standard specifies that the initial contac point (with the roof) is on the longitudinal centerline of the lower surface of the test device and 10 inches from the forwardmost point of the centerline. Your second question asks whether this 10-inch dimension should be maintained if this places the leading edge of the test device behind the leading edge of the roof and the A-pillars. You state that this would occur with certain roof configurations which tend to be high in the center (i.e., in which the leading edge of the roof is not the highest point of the roof). A manufacturer should adhere to the 10-inch dimension even if this means the leading edge of the test device will not be forward of the A-pillar and the roof's forward edge. The test procedures specified are standardized procedures which the agency applies to all passenger cars regardless of roof configuration. Thus, the agency would maintain the 10-inch dimension even when testing a roof with a higher center than its leading edge.; I would like to point out, however, that the test procedures specifie in the safety standards only document how the agency will conduct its compliance tests. Manufacturers are not required to test vehicles according to the procedures specified. A manufacturer's responsibility is to exercise due care to ascertain that its vehicles are in fact in compliance with the standards (15 U.S.C. 1397). If you are convinced that the procedures mentioned in your letter would accurately test the compliance of a particular vehicle with Safety Standard No. 216, you are certainly permitted to use those procedures. It is up to the manufacturer, however, to determine whether it has in fact exercised due care to determine compliance.; I hope this has been responsive to your inquiry. Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam0548OpenMr. H. Braun, Engineering Supervisor - Production, Motor Coach Industries, Inc., Pembina, ND 58271; Mr. H. Braun Engineering Supervisor - Production Motor Coach Industries Inc. Pembina ND 58271; Dear Mr. Braun: This is in reply to your letter of October 23, 1972, in which you as whether it is permissible under the Certification regulations for you to list alternative tire sizes and gross axle weight ratings on certification labels for vehicles which you sell without tires, but on which you apparently install them before delivery. You indicate that the tires are supplied by the customer, which he either owns, leases, or purchases from you.; Under the Certification regulation, you may if you wish lis alternative tire sizes, and alternative gross vehicle or gross axle weight ratings, as you described in your letter. If you install the tires, regardless of whether they are owned by the vehicle purchaser, leased, or purchased from you, the tire you install should be one of the alternative sizes listed on the certification label.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam2826OpenMr. Warren L. VanderLinden, Sales Manager, Minnesota Motor Company, P.O. Box 505, Fergus Falls, MN 56537; Mr. Warren L. VanderLinden Sales Manager Minnesota Motor Company P.O. Box 505 Fergus Falls MN 56537; Dear Mr. VanderLinden: Administrator Claybrook has asked me to respond to your recent lette concerning the installation of safety belts in the cargo area of a van vehicle for the purpose of securing wheelchair patients. Apparently, your legal counsel has advised you that such installation might be prohibited by Federal law or might give rise to private litigation problems in the future.; In answer to your questions, there is nothing under Federal law or th Federal motor vehicle safety standards that would prevent the installation of safety belts in the cargo area of a van to secure wheelchairs. In fact, Administrator Claybrook and the National Highway Traffic Safety Administration encourage you to make the installation requested by the senior citizens home. The safe transportation of disabled persons is currently a serious problem and every effort should be made to ameliorate the situation.; The only instance in which you would have any responsibilities unde Federal law would be an installation of additional safety belts prior to first purchase of the van by a consumer. In that case you would be a vehicle alteror, (sic) and under our certification regulations you would be required to place an additional label on the vehicle specifying that, as altered, the vehicle is still in compliance with all applicable safety standards (49 CFR 567.7, copy enclosed). For example, you should not destroy the vehicle's compliance with our Fuel System Integrity standard by penetrating the gas tank with the safety belt anchorage bolts.; Concerning your liability in private litigation, the general provision of negligence law would be applicable, as with any maintenance, repair or alteration done by a motor vehicle repair business. I must defer to the advice of your own counsel on that matter, however.; Once again, the agency does encourage the installation of safety belt for the securement of wheelchairs, since the disabled are seriously endangered without some type of restraint to protect them in a crash. Further, I believe that your fears of liability should be minimal as long as the installation is accomplished with normal consideration and due care.; Please contact Hugh Oates of my office if you have any furthe questions (202-426- 2992).; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam1709OpenMr. Peter N. Lalos, Mason, Fenwick & Lawrence, 310 O F C Building, 1730 Rhode Island Avenue, N.W., Washington, DC 20036; Mr. Peter N. Lalos Mason Fenwick & Lawrence 310 O F C Building 1730 Rhode Island Avenue N.W. Washington DC 20036; Dear Mr. Lalos: This responds to your November 15, 1974, request for a discussion o the responsibilities of a vehicle manufacturer to comply with Federal motor vehicle safety standards, and in particular, Standard No. 121, *Air brake systems*.; The National Traffic and Motor Vehicle Safety Act of 1966 (15 U.S. 1391 et seq.) provides:; >>>S 108. (a) No person shall -- (1) manufacture for sale, sell, offer for sale, or introduce i interstate commerce, or import into the United States, any motor vehicle or item of motor vehicle equipment manufactured on or after the date any applicable Federal motor vehicle safety standard takes effect under this title unless it is in conformity with such standard except as provided in subsection (b) of this section.<<<; Thus, the manufacture or sale of any vehicle which does not meet ever requirement of Standard No. 121 or any other applicable Federal motor vehicle safety standard is a violation of Federal law subject to a civil penalty of not more than $1,000 per violation (S 109). Each vehicle which does not comply with the dynamometer requirements you listed could constitute a separate violation of the act.; You suggested the standard of 'reasonable or due care' as the sol responsibility of a vehicle manufactured under the Safety Act. Section 108(b)(2) in part provides that S 108(a)(1) 'shall not apply to any person who establishes that he did not have reason to know in the exercise of due care' that a vehicle did not comply with an applicable standard. In order to comply with the Safety Act each manufacturer must design his vehicles and test program so as to exercise due care in assuring that each of his vehicles complies with the standard. Calculations based on principles of engineering could constitute an element in the exercise of 'due care'. I enclose a discussion of 'due care' which appeared in the preamble to a recent rulemaking on Standard No. 121.; Yours truly, Richard B. Dyson, Acting Chief Counsel |
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ID: aiam3734OpenMr. M. Iwase, Manager, Technical Administration Department, Koito Manufacturing Co., Ltd., Shizuoka Works, 500, Kitawaki, Shimuzu-shi, Shizuoka-ken, 424, Japan; Mr. M. Iwase Manager Technical Administration Department Koito Manufacturing Co. Ltd. Shizuoka Works 500 Kitawaki Shimuzu-shi Shizuoka-ken 424 Japan; Dear Mr. Iwase: This is in reply to your letter of June 22, 1983, to Mr. Medlin of thi agency asking for an interpretation of the recent amendment to Motor Vehicle Safety Standard No. 108 allowing use of replaceable bulb headlamp systems.; Regarding plastic lens materials, you have asked the limits o luminance transmittance loss and presence of haze after outdoor exposure test. These values are those specified by the referenced SAE standard, J576c.; You have also asked whether an accelerated weathering test i acceptable, such as ASTM E 838. Our reply is that you are free to conduct any accelerated weathering test you deem appropriate to support certification of compliance to Standard No. 108. We have not adopted any such test and will perform our compliance tests according to the 3-year test in SAE J576c.; Regarding the structural configuration of headlamps, you have aske about methods that may be acceptable to joining the lens and reflector, such as glue or welding. Standard No. 108 specifies no method for joining components, and any method is acceptable which results in an indivisible lens-reflector unit. Use of clips to supplement glue is permissible but use of clips alone would not result in an indivisible lens-reflector assembly. There is no objection to use of an additional rubber boot behind the reflector and bulb in the manner depicted in your letter. Drain holes, etc. may be provided as long as the headlamp complies with all the requirements of Standard No. 108. We shall publish in the near future a clearer indication of the headlamp terminal arrangement, as well as the dimensional specifications of the connector to the terminals of the bulb socket. We do not understand your request about the specific dimension and shape of each terminal 'blade' as the length, thickness, and width are already specified in the amendment (Figure 3-3). You have asked also whether the wattage values of 65 for the upper beam and 45 for the lower beam are maximum or nominal values. These values are maximum values.; Finally, concerning patent matters, you have asked whether certai aspects of the bulb and socket assembly are the subjects of patent claims. Ford has indicated in a letter of March 2, 1983, that, 'To facilitate compliance with the standard by all who wish to make or use replaceable bulb headlamps or their components, Ford Motor Company offers to grant royalty-free non-exclusive licenses to all manufacturers of motor vehicles, headlamps, or headlamp components that request such licenses, under U.S. patents and U.S. patent applications which claim these inventions to the extent that their use is needed to employ the proposed optional headlamp system.' If you have further questions on this issue you should write to Ford Motor Company.; I hope that this answers your questions. Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam1359OpenMr. David E. Martin, Manager, General Motors Corporation, Automotive Safety Engineering, Warren, MI 48090; Mr. David E. Martin Manager General Motors Corporation Automotive Safety Engineering Warren MI 48090; Dear Mr. Martin: This is in reply to your letter of December 3, 1973, requestin clarification of paragraph S5.1(c) of Motor Vehicle Safety Standard No. 217, Bus Window Retention and Release.' Your letter, and attached photograph of a push-out window, suggest that the words window frame' in S5.1(c) refer not to the window sash', the structure immediately surrounding the glazing material, but to the side of the bus.; We do not agree. The words window frame' in S5.1(c), with respect t the push out window, refer to the component that interfaces with the glazing.; The intent of S5.1 is to require a window retention system to be stron enough to retain occupants in a crash, at least up to the strength limit of the glazing itself. Since there are no limits on the movement of the window sash' relative to the bus structure, the interpretation you suggest would allow a window system that provides no retentive properties at all, thus defeating one of the main purposes of the standard.; Sincerely, Lawrence R. schneider, 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.