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: aiam0038OpenMr. H. F. Barr, Vice President, General Motors Technical Center, Warren, MI 48090; Mr. H. F. Barr Vice President General Motors Technical Center Warren MI 48090; Dear Mr. Barr: Thank you for your letter of November 13, 1967, in which approval of dynamic inertia load test procedure, as set forth in paragraph S4.3 of Federal Motor Vehicle Safety Standard No. 206, was requested.; This is to advise that the proposed procedure, as outlined in th enclosure to the referenced letter, is approved for the transverse inertia load portion of the standard test requirements.; Thank you for your continued cooperation in achievement of our mutua goals in motor vehicle safety.; Sincerely, William Haddon, Jr., M.D., Director |
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ID: aiam4978OpenMr. Masashi Maekawa Director, Technical Division Ichikoh Industries, Ltd. 80 Itado, Isehara City Kanagawa, 259-11, Japan; Mr. Masashi Maekawa Director Technical Division Ichikoh Industries Ltd. 80 Itado Isehara City Kanagawa 259-11 Japan; "Dear Mr. Maekawa: This responds to your letter of February 21, 1992 asking for a clarification of our letter of December 18, 1991. In that letter we discussed 'a combination tail/stop lamp that would be mounted on the deck lid ('Lamp B') immediately adjacent to a combination tail\stop lamp that is mounted on the vehicle body ('Lamp A')'. You informed us that each lamp complied with the requirement for effective projected luminous lens area, but that neither complied with photometric requirements. You asked whether Ichikoh could consider the two adjacent lamps as one lamp for purposes of measuring photometrics. We replied that it was not possible to consider the two lamps as one, and that we regarded the lamp that was on the vehicle body as the one that should be designed to conform to Standard No. 108. You have asked whether this advice is consistent with an interpretation given Mazda on June 28, 1985, with respect to a similar design. That letter informed Mazda that compliance of the design would be judged with the vehicle in its normal driving position, thereby implicitly agreeing that the two lamps could be considered one for photometric purposes. The difference in the interpretations originated in the way each manufacturer described its design. Ichikoh referred to its design as two adjacent lamps. Mazda described its configuration as a (single) lamp constructed so that a portion of it is fixed to the body and a portion on the decklid. Our review of the two designs shows that they are essentially similar, and that the Mazda design comprises, in fact, two adjacent lamps. As it was not our intent to change the earlier interpretation, we confirm that the June l985 interpretation remains valid, and that the December 1991 letter is overruled to the extent that it is inconsistent with it. Sincerely, Paul Jackson Rice Chief Counsel"; |
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ID: aiam0192OpenMr. Warren M. Heath, Commander, Engineering Section, Department of California Highway Patrol, P. O. Box 898, Sacramento, CA 95804; Mr. Warren M. Heath Commander Engineering Section Department of California Highway Patrol P. O. Box 898 Sacramento CA 95804; Dear Mr. Heath: Thank you for your letter of December 8, 1969, concerning alternat flashing of side marker lamps with turn signal lamps.; Alternate flashing sidemarker lamps are permitted in paragraph S3.5 o Motor Vehicle Safety Standard No. 108 for signaling purposes, however, they must not impair the effectiveness of the turn signal lamps as required in paragraph S3.1.2.; Sincerely, Charles A. Baker, Office of Standards on Accident Avoidance Motor Vehicle Safety Performance Service; |
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ID: aiam2455OpenMr. B. R. Weber, Executive Vice President, Wesbar Corporation, Box 577, West Bend, WI, 53095; Mr. B. R. Weber Executive Vice President Wesbar Corporation Box 577 West Bend WI 53095; Dear Mr. Weber: This is in reply to your letter of October 28, 1976, asking severa questions with respect to that portion of paragraph S4.4.1 of Motor Vehicle Safety Standard No. 108 which prohibits the optical combination of clearance and tail lamps. You have also expressed your concern, in a recent telephone conversation with Mr. Vinson of my staff, about the ACUTEK interpretation of October 22, 1976, to be discussed below.; The distinction between the hypothetical lamp in Question 2 of you letter of September 7, 1976, and the Acutek lamp is that there is no opaque barrier wall in the former, separating the tail lamp bulb and the clearance lamp bulb, while in the latter the barrier rises to the base of the bulb. Since Standard No. 108 does not require separate compartments (i.e., an opaque barrier) for tail lamps and clearance lamps, it is obvious that the prohibition against optical combination means that (a) a single bulb may not perform both functions and (b) a single bulb must not be perceived as performing both functions. This was the rationale behind Mr. Driver's advice to Acutek that the available data indicated 'that when the tail lamp bulb [on the Acutek lamp] is activated independently from the clearance lamp bulb, and vice versa, there is no appreciable amount of incidental light emitted from the lens of the clearance lamp,' and that 'the amount of light 'spill' appears to be so small that it would not be interpreted (by a driver following the vehicle on which it is installed) as illuminating the lens of the tail lamp when operated in the clearance lamp mode, and vice versa.'; If you apply this general principle to the questions you asked then think you will have the answers. The principle is necessarily dependent upon the candlepower output of any lamp to which it is applied, a value not given in your questions. Thus, the principle cannot be quantified and the determination of the extent of light spill is necessarily subjective, and certification is dependent upon a manufacturer's good faith in attempting to achieve compliance.; After reviewing this matter I must admit that I am curious as to th safety rationale behind the prohibition. Paragraph S4.4.1 had its genesis in a similar provision in Bureau of Motor Carrier Safety regulations (49 CFR 393.22(b)(3), formerly 393.22(c)) and was adopted in conformance with it. The Society of Automotive Engineers, however, does not prohibit combining these lamps. If clearance lamps are mounted below 72 inches--the maximum allowable mounting height for tail lamps--it may be that they could be combined with tail lamps, without any detriment to safety, and at a saving to the consumer. Perhaps you would like to comment on this.; Sincerely, Frank A. Berndt, Acting Chief Counsel |
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ID: aiam0468OpenMr. Fredrick A. Stewart, Vice President, Safety and Quality Assurance, American Motors Corporation, 14250 Plymouth Road, Detroit, MI, 48232; Mr. Fredrick A. Stewart Vice President Safety and Quality Assurance American Motors Corporation 14250 Plymouth Road Detroit MI 48232; Dear Mr. Stewart: This is in response to your recent telephone inquiry as to whether th recent amendment of Standard 215, Exterior Protection, requires that vehicles meet the photometric requirements of Standard 108 after being subjected to the Standard 215 impacts.; S5.3.1 of Standard 215 reads: >>>'Each lamp or reflective device, except license plate lamps, shal be free of cracks and shall comply with the applicable requirements of Motor Vehicle Safety Standard No. 108.'<<<; S4.3.1.1 of Standard 108 reads in relevant part: >>>'Each lamp and reflective device shall be located so that it meet the visibility requirements specified in any applicable SAE Standard or Recommended Practice. *In addition, no part of the vehicle shall prevent the device from meeting the photometric output at any test point specified* in any applicable SAE Standard or Recommended Practice.'(Emphasis supplied.)<<<; Thus, although the actual photometric tests may be considered 'benc test', that is, tests whose procedures include removing the devices from the vehicle, the above provision of Standard 108 requires that the configuration of the vehicle external to the devices not prevent them from meeting the photometric requirements. The test procedures themselves require the devices to be placed in their actual orientation on the vehicle. Therefore, the provision in Standard 215 that the lamps and reflective devices shall meet all the requirements of Standard 108 after the impacts includes the photometric requirements.; Sincerely, Robert L. Carter, Acting Associate Administrator, Moto Vehicle Programs; |
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ID: aiam5390OpenMr. Paul L. Anderson President Van-Con Inc. P.O. Box 237 Middlesex, NJ 08846-0237; Mr. Paul L. Anderson President Van-Con Inc. P.O. Box 237 Middlesex NJ 08846-0237; Dear Mr. Anderson: This responds to your letter of May 19, 1994 requesting an interpretation of the requirements of S5.5.3(c) of Standard No. 217, Bus Emergency Exits and Window Retention and Release. Section S5.5.3(c) reads: Each opening for a required emergency exit shall be outlined around its outside perimeter with a minimum 3 centimeters wide retroreflective tape, either red, white or yellow in color ... Your letter states that you are unable to continuously outline the perimeter of the rear emergency doors on your school buses due to the proximity of door hinges, tail light lenses, and a rubber gasket between the bottom edge of the door and the bumper. You ask: Would we be in compliance with Reflective Tape requirements of FMVSS 217 if we put a continuous strip of tape across the top of both Emergency Rear Doors on the roof cap above the doors and down the left and right side of the double door opening with breaks in the tape for door hinges & tail light lenses. This would outline the Emergency Rear Doors on three sides. No tape would be put across the bottom? As an alternative, if the above is not acceptable, could we put tape across the bottom on the doors? As explained below, your planned placement for the top and sides of the door, and your alternative placement for the bottom of the door would be acceptable. In a July 7, 1993 letter to the Blue Bird Body Company, NHTSA stated: NHTSA interprets S5.5.3(c) to allow interruptions in the tape necessary to avoid and/or accommodate curved surfaces and functional components, such as rivets,rubrails, hinges and handles, provided, however, that the following requisites are met. In the November 2, 1992, final rule, NHTSA indicated that the purpose of the retroreflective tape would be to identify the location of emergency exits to rescuers and increase the on- the-road conspicuity of the bus. Accordingly, the retroreflective tape may have interruptions if they satisfy both of these purposes. The occasional breaks in the tape you described would not appear to negatively affect a rescuer's ability to locate the exits, or reduce the conspicuity of the bus. However, the tape should be applied as near as possible to the exit perimeter... When rivets are present, NHTSA will defer to a manufacturer's decision to apply the retroreflective tape immediately adjacent to the rivets, rather than over the rivets, if the manufacturer decides that this will increase the durability of the tape. According to this July 1993 letter, interruptions in the retroreflective tape to avoid and/or accommodate hinges (such as the hinge on the side of the rear emergency door) and other functional components are permitted if the interruption does not negatively affect a rescuer's ability to locate the exits, or does not reduce the conspicuity of the bus. NHTSA considers tail light lenses to be 'functional components' which do not have to be covered by the retroreflective tape. (Indeed, placement of the tape on the tail light lense could affect the efficacy of the light.) The interruptions in the tape for these components would not appear to negatively affect a rescuer's ability to locate the exits, or reduce the conspicuity of the bus. Thus, the interruptions are permitted for the tape along the sides of your door. With regard to the bottom of your door, based on the pictures provided with your letter, it appears that there is no location available for the placement of retroreflective tape outside of the door's bottom edge. Since not outlining an entire side of an exit might affect a rescuer's ability to locate the exit and would reduce the conspicuity of the exit, the bottom side of the door must be marked with the retroreflective tape. In this situation, NHTSA interprets S5.5.3(c) as allowing placement of the retroreflective tape on the door itself, as near as possible to the lower edge of the door. I hope you find this information helpful. If you have any other questions, please contact Mary Versailles of my staff at this address or by phone at (202) 366-2992. Sincerely, John Womack Acting Chief Counsel; |
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ID: aiam4997OpenMr. Michael F. Hecker Micho Industries P.O. Box 1791 Goleta, CA 93116; Mr. Michael F. Hecker Micho Industries P.O. Box 1791 Goleta CA 93116; "Dear Mr. Hecker: This responds to your letter of April 2, 199 concerning possible interpretations of section S5.1.4(c) of Federal Motor Vehicle Safety Standard No. 222, School bus passenger seating and crash protection, as it applies to the R-BARR Passenger Restraint System (R-BAR). (While your letter refers to section S5.1.2(c), you clarified in a telephone conversation with Mary Versailles of my staff that your concerns relate to section S5.1.4(c).) The R-BAR is a padded restraining device, and the ends of the device attach to the rear of a school bus seatback. The device folds down for the purpose of restraining the passengers seated in the next rearward seat. Your letter states that Micho Industries believes that: A. The standard is not applicable to the R-BAR passenger restraint. B. The R-BAR complies with the intent of Standard No. 222. To support these statements you offer the following reasons: 1. The R-BAR is not a fixed position device, nor is it a rigid component of the seat structure. 2. In the event of a rear impact, the R-BAR incorporates a design that allows it to move upward, and away, from the adjoining seat which would thus allow the minimum clearance as intended. 3. The standard in question (571.222, section S5.1.4(c)) was written without the authors having the benefit of knowledge of this type of device and thus allowances were not included for its possible use. The issue of whether Standard No. 222 is applicable to a device such as the R-BAR has been addressed previously by this agency. Enclosed are copies of four letters concerning similar devices (Mr. Joseph F. Mikoll, November 3, 1988, and March 10, 1989, The Honorable Robert J. Lagomarsino, January 8, 1990, and Mr. Scott K. Hiler, January 31, 1991). Those letters make it clear that if a device such as the R-BAR is installed in any new school bus, the school bus manufacturer must certify that the vehicle meets all applicable safety standards with the device installed. The letters also make it clear that such devices may not legally be installed in used school buses by commercial establishments such as repair businesses if the effect of such installation is to take the vehicle out of compliance with any safety standard. With respect to your assertion that the R-BAR complies with the intent of Standard No. 222, the National Traffic and Motor Vehicle Safety Act requires NHTSA to issue Federal motor vehicle safety standards that prescribe objective requirements. Under the Act, manufacturers must certify that their products comply with the requirements of all applicable standards and not merely with some alleged 'intent' of a standard. Further, manufacturers may not certify products based on speculation that the agency would have established different requirements had it known of a particular design. With regard to your specific concerns about S5.1.4(c), that section states that when a seat back is subjected to a specified force, '(t)he seat shall not deflect by an amount such that any part of the seat moves to within 4 inches of any part of another passenger seat in its originally installed position.' In the enclosed letter to Mr. Hiler, the agency stated that 'once the restraining bar is attached to the seatback, it is part of the seatback.' Therefore, the R-BAR would be considered a part of the seat subject to the requirements of S5.1.4.(c) Section S5.1.4(c)'s requirements are not limited to rigid components of a seat, and therefore the fact that the R-BAR is not a fixed position device is not relevant to the applicability of those requirements. With respect to your argument that the device will move upward and away in the event of a rear impact, Standard No. 222 sets forth a specific test procedure for the requirement specified in S5.1.4(c). Manufacturers are required to certify that a vehicle complies with the requirements of the standard when tested in accordance with that test procedure. I hope you find this information helpful. If you have any other questions, please contact Mary Versailles of my staff at this address or by phone at (202) 366-2992. Sincerely, Paul Jackson Rice Chief Counsel Enclosures"; |
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ID: aiam2140OpenMr. L. A. MacEachern, Cal Light Company, 50 Oak Court, Walnut Creek, CA 94596; Mr. L. A. MacEachern Cal Light Company 50 Oak Court Walnut Creek CA 94596; Dear Mr. MacEachern: This is in reply to your letter of November 4, 1975, telling us of you wish to market a rectangular sealed beam headlamp unit for motorcycles. In your opinion this might be prohibited by 'federal inaction to update FMVSS-108 SAE J584 April 1964 to the amended SAE J584b December 1971.'; Substitution of J584b would not be a solution to your problem since i does not specify a Type 2A sealed-beam headlamp unit as one of the approved options. There would have to be both a substitution of J584b and a provision in Standard No. 108 itself that either a Type 2 or Type 2A sealed beam headlamp unit may be used. I enclose a copy of a regulation that tells how you may submit a petition for rulemaking for an appropriate amendment to Standard No. 108.; You also enclosed a letter from the California Highway Patrol statin that it was amending its regulations; >>>'to allow the use of motorcycle headlamps which comply with the typ 2 lower beam photometric requirements and the motorcycle upper beam requirements, though we are not sure what position NHTSA would take upon this interpretation'.<<<; Such action by the California Highway Patrol appears precluded b Section 103(d) of the National Traffic and Motor vehicle Safety Act of 1966. The effect of this section is to prohibit California from having a State lighting standard that differs in any way from Standard No. 108. Since the Federal lighting standard does not allow the California amendment, the State regulation appears invalid.; Notwithstanding California's 'approval' of your headlamp, your sale o this rectangular headlamp for motorcycles as either original equipment or as replacement equipment (but only for motorcycles manufactured on or after January 1, 1972) would appear to be a violation of Section 108(a) (1) (A) of the Act, unless and until Standard No. 108 is amended. There is a maximum penalty of $1,000 for each violation, up to $800,000 for any related series of violations.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam0487OpenMr. C. D. Snead, Vice President, Eastman Chemical Products, Inc., 500 12th Street, S.W., Washington, DC 20024; Mr. C. D. Snead Vice President Eastman Chemical Products Inc. 500 12th Street S.W. Washington DC 20024; Dear Mr. Snead: This is in reply to your letter of November 1, 1971, concerning th status of your petition to amend Motor Vehicle Safety Standard No. 205, 'Glazing Materials', to allow the use of Uvex plastic sheet in motor vehicles. You request our comments regarding three matters which you list, and which are incorporated into our responses below.; You ask us to 'explain that Uvex Sheet Plastic is and has been unde active consideration for vehicle glazing approval for some time and an early decision is anticipated.' A notice of proposed rulemaking to amend Standard No. 205 (Docket No. 71-1) was published January 9, 1971 (36 F.R. 326). This notice would allow the use in motor vehicles of plastic materials, not presently allowed, that meet certain specified requirements. This notice is based in part upon a petition submitted by Eastman Chemical. The requirements do not refer to Uvex or any other material by name. The Administration takes no position on whether Uvex material would meet the proposed requirements. A final decision based on this notice is anticipated in the near future.; The notice of proposed rulemaking of January 9, 1971, does, as yo indicate, propose other amendments to Standard No. 205. Some of these proposals have engendered substantial interest from industry and have consequently affected the amount of Agency work involved in the rulemaking action.; Finally, you ask if State highway standards preventing the use of Uve will continue to be effective if Uvex is allowed to be used under the Federal standards. Under section 103(d) of the National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1392(d)), a State motor vehicle safety standard applicable to a particular aspect of motor vehicle or motor vehicle equipment performance must be identical to a Federal motor vehicle safety standard applicable to that same aspect of performance. Consequently, a State vehicle standard prohibiting all use of Uvex would be pre-empted to the extent that amendment of Standard No. 205 permits its use.; I hope this clarifies the situation for you. Sincerely, Lawrence R. Schneider, Chief Counsel |
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ID: aiam2510OpenMr. W. G. Milby, Manager, Engineering Services, Blue Bird Body Company, P. O. Box 937, Fort Valley, GA 31030; Mr. W. G. Milby Manager Engineering Services Blue Bird Body Company P. O. Box 937 Fort Valley GA 31030; Dear Mr. Milby: This responds to your December 20, 1976, request for confirmation tha the National Highway Traffic Safety Administration (NHTSA) intends to test the leg protection zone in Standard No. 222, *School Bus Passenger Seating and Crash Protection*, in such a manner as to ensure that the entire knee form will contact with the seat back or restraining barrier and will not extend beyond them.; The knee form contact area measurement required by Standard No. 222 wa intended to measure the distribution of forces over an adequate area of the knee in an impact situation. The measurement is meaningful, therefore, only when the contact area is tested in a manner that provides opportunity for the knee form to contact with the seat back or restraining barrier to the fullest extent possible. In accordance with the intent of the standard the agency will not test the contact area in any configuration where the hemispherical surface of the knee form testing device extends beyond the test surface.; Sincerely, Frank A. Berndt, Acting 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.