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 |
|---|---|
ID: aiam2940OpenMr. Stephen E. Hall, President, Esley Development Corporation, 6415 S.W. Canyon Ct., Suite 40, Portland, OR 97221; Mr. Stephen E. Hall President Esley Development Corporation 6415 S.W. Canyon Ct. Suite 40 Portland OR 97221; Dear Mr. Hall:This is in reply to your letter of December 21, 1978 asking about your responsibilities, as the manufacturer of a snow plow headlamp holder, under the National traffic and motor Vehicle Safety Act.; Under the Act a truck, with or without snow plow attachment, is 'motor vehicle' and the plow itself and any associated equipment is considered 'motor vehicle equipment' since it is an accessory or addition to a motor vehicle. But Federal Motor Vehicle Safety Standard No. 108, *Lamps, Reflective Devices and Associated Equipment*, contains no requirements either for snow plow or accessory lighting, and your sealbeam holder therefore is not subject to regulation under the standard. However, as a manufacturer of 'motor vehicle equipment,' you are responsible for notification of purchasers and dealers, and remedy of any safety-related defects that may occur in your product. (Sec. 151 *et seq.* of the Act); As to 'what legal burden rests' with you as a 'manufacturer of th sealbeam holder as to the possible misuse' of your units once they leave your plant, we are uncertain what you mean by 'misuse.' If you mean that the holder is used in a way that you did not intend, then the question would appear to be one not answerable under Federal law. If the 'misuse' is attributable to a defect in the sealbeam holder, then the question would arise whether the defect is safety-related. If the answer is affirmative, then you would be subject to the notification and remedy provisions of the Act mentioned in the preceding paragraph.; We are forwarding a copy of your letter to the Federal Highwa Administration, Bureau of Motor Carrier Safety, for a reply to your question as to what Federal requirements must be met for use of your units 'on inter and intra state highways.'; Enclosed is a copy of Standard No. 108 as you requested, as well as copy of the Act.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
|
ID: aiam1395OpenMr. W. G. Milby, Project Engineer, Blue Bird Body Company, P.O. Box 937, Fort Valley, GA, 31030; Mr. W. G. Milby Project Engineer Blue Bird Body Company P.O. Box 937 Fort Valley GA 31030; Dear Mr. Milby: This is in reply to your letter of January 15, 1974, asking whether school bus rear lighting system is permissible that activates the back-up lamps and flashes four red stop lamps when the gearshift is in reverse.; The system of supplemental school bus warning lamps you describe is on that is not specified by Standard No. 108. Although S4.6(b) states that 'All . . . lamps [other than those specified in S4.6(a)] shall be steady burning. . . ,' we interpret this requirement as covering only the systems specified by the standard. Therefore there is no Federal prohibition against your installation of such a system. However, the system would be subject to regulation by the individual States, some of which may have restrictions on the use of flashing lights.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
|
ID: aiam3202OpenMr. J. Kawano, General Manager, U.S. Representative Office, Toyota Motor Co., Ltd., One Harmon Plaza, Secaucus, NJ 07094; Mr. J. Kawano General Manager U.S. Representative Office Toyota Motor Co. Ltd. One Harmon Plaza Secaucus NJ 07094; Dear Mr. Kawano: This responds to your recent request for an interpretation concernin the proper designated seating capacity for the rear seat in several Toyota vehicle models (Corolla Sedan, Corolla Coupe, Corona Sedan and Starlet). You assert that the rear seat hip room in these models ranges from 39.4 inches to 42.6 inches, and ask whether the vehicles would qualify as having only two designated seating positions.; Under the strict measurement technique specified in the amende definition of 'designated seating position' (SAE J1100a), the Toyota vehicle models in question would have the hip room dimensions you state. This is due to the fact that the SAE procedure specifies that hip room is to be the minimum dimension of the seat cushion. The Toyota designs include wheel wells and contoured side paddings at the intersection of the seat back and seat cushion that establish the minimum dimension of the seat. However, these structures only extend out 4 to 5 inches (approximation) from the seat back. If the hip room of the rear seats is measured midway of the seat cushion, all of the designs have greater than 50 inches of hip room, and ostensibly should have three designated seating positions. Nevertheless, since according to the measurement technique specified in the definition these seats have substantially less than 50 inches of hip room, the agency must conclude that the rear seats could qualify as having only two designated seating positions. This opinion is accompanied with several candid remarks, however.; The effective hip room of the Toyota seat designs is much greater tha the approximately 40 inches that is obtained by the technical measuring technique specified in the definition. If two outboard occupants move their hips several inches forward from the seat back in these vehicle designs, the wheel-wells and contoured side paddings are no longer impediments and there is over 50 inches of hip room, as noted above. Moreover, the design of these rear seats is such that use of the center position is 'invited.' There is at least 10 to 12 inches of well-padded hip room at the center portion of the seat between the inboard ends of the two seat belt assemblies installed in the seats. The manufacturer has given no indication that this space is not intended for occupancy. The agency is also concerned that this center position has no belt assembly to secure a child restraint system, particularly since the rear- center seat is statistically the safest position in a vehicle.; Frankly, with the wide center space that is available in these rea seat designs, we do not believe the manufacturer has made a sincere attempt to indicate to vehicle occupants that the seats are intended for use by only two occupants. It would be a simple matter for the manufacturer to make this obvious by use of a fixed armrest or some other impediment to use of the position. Furthermore, we believe that this message can be given to occupants without otherwise compromising the design the manufacturer wishes to achieve. If the manufacturer does not in fact wish to market the vehicles as having three-passenger rear seats, we do not understand why wide, well-padded center positions are present.; Finally, I am enclosing a copy of an earlier interpretation whic discusses the measurement procedure included in the definition of 'designated seating position.' As that interpretation pointed out, the agency will not allow manufacturers to avoid the obvious intent of the definition by finding 'loopholes' in the specified measurement procedure. If designs such as those displayed in the Toyota vehicles persist, without some clear indication that the center position is not to be used, the agency may find it necessary to amend the definition to provide that the hip room measurement is to be taken at the midpoint of the seat cushion. We hope that manufacturers will voluntarily alter designs of this type to conform to the intent of the definition, so that such an amendment is not necessary.; Sincerely, Frank Berndt, Chief Counsel |
|
ID: aiam4528OpenThe Honorable Douglas H. Bosco House of Representatives Washington, DC 20515; The Honorable Douglas H. Bosco House of Representatives Washington DC 20515; Dear Mr. Bosco: This is in reply to your letter of June l6, l988, wit reference to your constituent Jerry Yost of Occidental. Thank you for enclosing our previous correspondence on Mr. Yost's C-More Light invention. This device is a relay which would allow a headlamp's lower beam to remain in operation when the upper beam is activated. In my reply of August 3, l987, I advised you that the Federal motor vehicle lighting standard explicitly prohibits simultaneous activation of upper and lower beams in four-lamp headlighting systems other than the one we call Type F (S4.5.8 of 49 CFR 57l.108 Motor Vehicle Safety Standard No. 108). I explained that our historical concern has been that the maximum candlepower limitations of the Federal standard might be exceeded. In your latest letter, you have enclosed a copy of a test report by Industrial Testing Laboratories and a letter from the California Highway Patrol. You have asked the steps, if any, that Mr. Yost should take to market legally his device. The test report is intended to show that maximum candela will not be exceeded when the device is used in a four-lamp headlamp system. California advised that the device appeared legal to install on vehicles equipped with Type F headlamp systems, and that 'this system is also permitted by California law as long as the photometric output is within the standards established for any other type of headlight. The ITL tests appear to show compliance'. We have reviewed the ITL test report, and find it indicative of the features and limitations of Mr. Yost's system. The test report shows a failure of the dual filament 2A1 lamp (second column from the left) at test point 4D-V where 3490 candlepower is measured. Note the maximum limitation of 2500 candlepower at that test point (third column from the right, same line). Contrasted with this is an unusually low reading of 2540 candlepower for the same test point with the single filament 1A1 lamp (third column from the left) when up to 5000 candela is allowed (fourth column from the right). The net result, however, is that the combined maximum of 6030 candlepower (fourth column from the left) is well within the allowable 7500 maximum of Standard No. 108 (first column from the right). In essence, the test report indicates that the light at test point 4D-V produced by the system under test does not achieve the balance contemplated by the standard, although the light at other test points meets the requirements of the standard. While the test report indicates that a system using the lamps tested might conform to Standard No. 108, this was achieved by using what appear to be two lamps of moderate performance. The agency believes it likely that replacement headlamps for such a system would more likely approach the maxima prescribed for 4D-V and other test points for Type 1A1 and 2A1 headlamps with the result that simultaneous operation of upper and lower beams would exceed the established limits. In other words, although an original equipment headlighting system using the relay might meet Federal photometric specifications, there is no assurance that replacement lights would. Type F systems have been designed to preclude exceeding the maxima. Thus, our concern remains for lighting systems using lamps other than Type F. The agency's views on simultaneous operation are discussed in further detail in a Federal Register notice published in l986, a copy of which I enclose (Docket No. 81-11, Notice l4). As I indicated before Mr. Yost's device may be legally installed as original or aftermarket equipment on any passenger car equipped with a Type F headlamp system. Use with any other original equipment headlighting system is expressly prohibited by Standard No. 108. As for aftermarket applications other than Type F, he should be aware of the statutory section (15 USC 1397(a)(2)(A)) prohibiting manufacturers, distributors, dealers, and motor vehicle repair businesses from rendering inoperative, in whole or in part, any equipment installed in accordance with a safety standard if installation of the relay would result in a noncompliance with Standard No. 108. We are providing a copy of this letter to the California Highway Patrol so that it may be aware of our views on this subject. Mr. Yost and the agency share a common desire to improve foreground lighting, a subject currently under study at NHTSA. We appreciate his interest in motor vehicle safety. Sincerely, Erika Z. Jones Chief Counsel Enclosure cc: Department of California Highway Patrol P.O. Box 942898 Sacramento, CA 94298-0001; |
|
ID: aiam3717OpenDavid I. Fallk, Esq., Robert W. Munley, P.C., Floor Eight, Penn Security Bank Building, P.O. Box 1066, Scranton, PA 18503; David I. Fallk Esq. Robert W. Munley P.C. Floor Eight Penn Security Bank Building P.O. Box 1066 Scranton PA 18503; Dear Mr. Fallk: This responds to your letter of July 11, 1983, concerning Standard No 121, *Air Brake Systems*, and the *PACCAR* case. The answers to your questions are as follows.; Your first question was whether, following *PACCAR*, a manufacturer wa required to comply with the applicable 121 standard for trucks which had been assembled but not delivered. The answer to that question is no, for the portions of the standard that were invalidated by the court. As noted in an enclosed letter (dated March 4, 1980), NHTSA concluded that the 'no lockup' and 60-mph stopping distances had been invalidated from the effective date of the standard. Therefore, after *PACCAR*, no manufacturer was required to comply with those invalidated portions of the standard, whether or not a vehicle had already been assembled.; Your second question concerned whether a manufacturer or anyone else i properly informed was prevented from disabling the anti-lock system, before it was put into service. The answer to that question is no. That issue is fully explained in two enclosed letters (dated September 11, 1979, and March 4, 1980). These letters explain the relationship of what your letter refers to as the section of the vehicle safety act to prevent disabling and Standard No. 121, in light of the *PACCAR* case.; I have also enclosed a letter (dated November 29, 1979), whic discusses the nature of Standard No. 121 as a performance standard. If you have any further questions, please call Edward Glancy of my staff at 202-426-2992.; Sincerely, Frank Berndt, Chief Counsel |
|
ID: aiam0838OpenMr. G. Harrison, General Manager, Protector Africa (Pty.) Ltd., P. O. Box 20, Kempton Park, Transvaal, South Africa; Mr. G. Harrison General Manager Protector Africa (Pty.) Ltd. P. O. Box 20 Kempton Park Transvaal South Africa; Dear Mr. Harrison: This is in reply to your letter of July 31, 1972, in which you reques that your motorcycle helmet be tested by our testing authority. The National Highway Traffic Safety Administration does not provide approval of any item of motor vehicle equipment as conforming to any motor vehicle safety standard. Each item is required to conform, but the basis upon which a manufacturer determines whether his product conforms to a standard is a matter within his own discretion.; We thank you for your compliments and for your comments on the propose standard for motorcycle helmets, which have been placed in the rulemaking docket.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
|
ID: aiam2805OpenMr. 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 February 9, 1978, letter asking how to measur the head form contact area in Standard No. 222, *School Bus Passenger Seating and Crash Protection*.; In your first paragraph, you indicate that the National Highway Traffi Safety Administration (NHTSA) has allowed the knee form contact area measurement to be undertaken on or within a line 1 1/2 inches from the edge of the leg protection zone to ensure that the knee form will contact the entire surface. You ask that a similar line be established for the head protection zone contact areas.; As you know, the head form contact area requirements apply to mor areas than do the knee form contact area requirements. The knee form contact area requirements apply only to seat backs and the backs of restraining barriers. The head form contact area, on the other hand, includes anything falling within a specified zone which might include the sides or tops of seats. Therefore, it is impossible to create fictional lines around the outer edges of objects that fall within the head protection zone for purposes of testing the compliance of those objects with the requirements. The agency notes further that it never stated that it would test knee form contact area on or inside a line 1 1/2 inches from the edge of a seat back or restraining barrier. The agency did state that it would test in a manner that 'provides opportunity for the knee form to contact with the seat back or restraining barrier to the fullest extent possible.' That interpretation can also be applied to the head form contact area requirements.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
|
ID: aiam4178OpenWilliam Shapiro, P.E., Manager, Regulatory Affairs, Volvo Cars of North America, Rockleigh, NJ 07647; William Shapiro P.E. Manager Regulatory Affairs Volvo Cars of North America Rockleigh NJ 07647; Dear Mr. Shapiro: Thank you for your letter of May 5, 1986, requesting an interpretatio of how the requirements of Standard No. 212, *Windshield Retention*, apply to a passenger car that is equipped with a driver-only air bag system. As explained below, such a vehicle must retain not less than 50 percent of the windshield periphery after being tested in accordance with Standard No. 212.; Standard No. 212 sets different windshield retention requirements for vehicle depending on whether it is equipped with passive or manual restraints. S5.1 of the standard provides that vehicles equipped with passive restraints must retain not less than 50 percent of the windshield periphery after crash testing. S5.2 of the standard provides that vehicle (sic) that are not equipped with passive restraints must retain not less than 75 percent of the windshield periphery.; You noted that S4.1.3.4(b) of Standard No. 208 provides that, fo purpose of calculating the number of passive restraint-equipped cars during the phase-in of passive restraints, a car with a driver-only, non-belt passive restraint will be counted as a vehicle complying with the passive restraint requirements of S4.1.2.1(a). Such a driver-only system can have a manual safety belt installed at the right front passenger position. You said that Volvo considers a vehicle with a driver-only, non-belt system to be a passive restraint vehicle and thus subject to the 50 percent windshield retention requirement of S5.1 (sic); As discussed in a July 5, 1977, Federal Register notice (42 FR 34288) one of the reasons the agency adopted the 50 percent retention requirement for passive restraint-equipped vehicles was because there could be contact between an air bag system and the windshield. In addition, there could be incidental contact between an air bag- restrained test dummy and the windshield. Because the same air bag-to-windshield and dummy-to-windshield contact is possible in a vehicle equipped with a driver-only air bag system, the agency believes that it is appropriate to apply the 50 percent retention requirement to a driver-only air bag system.; If you have any further questions, please let me know. Sincerely, Erika Z. Jones, Chief Counsel |
|
ID: aiam1680OpenMr. Quentin H. McDonald, The Bobby-Mac Company, Inc., P.O. Box 209, Scarsdale, NY 10583; Mr. Quentin H. McDonald The Bobby-Mac Company Inc. P.O. Box 209 Scarsdale NY 10583; Dear Mr. McDonald: This is in reply to your letter of October 10, 1974, to Mike Peskoe requesting our opinion that a draft label you plan to affix to the Bobby-Mac 2-in-1 Baby Chair will conform to the requirements of Motor Vehicle Safety Standard No. 213. Your letter indicates that although the Bobby-Mac 2-in-1 Baby Chair is not sold as a child seating system, you will be marketing a conversion kit which will enable purchasers to convert it into child seat use. With the conversion kit, the 2- in-1 Baby Chair will become the identical car child seat that you sell as the Bobby-Mac 2-in-1 Car Seat and the 3-in-1 Baby Chair.; We believe that attachment of the required label to the 2- in-1 Bab Chair, even though the chair is not a child seating system until the conversion kit is purchased, is the most satisfactory method of achieving conformity with Standard No. 213. Both of the additions you will make to the existing Bobby- Mac label are in keeping with the purpose of Standard No. 213's labeling requirements, and we will consider the draft label you enclose to conform to the labeling requirements of Standard No. 213 provided that the month and year of manufacture are included on the label.; As a suggestion, it seems to us that there should be a Part No reference to the conversion kit on the label. This might reduce any confusion with the other conversion kits that you offer for the other Bobby-Mac devices.; We are pleased to be of assistance. Yours Truly, Richard B. Dyson, Acting Chief Counsel |
|
ID: aiam0992OpenMr. John F. McCuen, Kelsey-Hayes Company, Romulus, MI 48174; Mr. John F. McCuen Kelsey-Hayes Company Romulus MI 48174; Dear Mr. McCuen: This is in reply to your letters of October 23, 1972 and January 25 1973, concerning the intent of the antilock performance requirements of Motor Vehicle Safety Standard No. 121. I apologize for our delay.; Your question arises from an amendment to S5.3.1 of the standard. A originally adopted in February 1971, the section required that the vehicle be capable of stopping without wheel lockup except for 'momentary' lockup allowed by an antilock system. As amended in February 1972, the word 'controlled' is used in place of 'momentary', so that the section now provides that stops are made; >>>without lockup of any wheel at speeds above 10 m.p.h. except fo controlled lockup of wheels allowed by an antilock system . . . .<<<; In making this change, the agency had in mind the type of antiloc system that was designed to permit one wheel on an axle to lock under some circumstance while the other wheels continued to turn. It was thought that adequate control could be attained by such systems, and the standard was amended accordingly.; The question you raise is whether a system could be designed in whic all wheels could be permitted to lock for substantial periods, so long as they are 'controlled' by an antilock system. As you correctly indicate, the term 'controlled', unlike 'momentary', is not a time-related word. Our answer, therefore, is that such an antilock system would be permitted under the standard as it now stands.; It is our present opinion, however, that such a system would probabl not provide an acceptable level of performance. If it appears that such a system would be installed, it is likely that we would undertake rulemaking action to prohibit it.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
Request an Interpretation
You may email your request to Interpretations.NHTSA@dot.gov or send your request in hard copy to:
The Chief Counsel
National Highway Traffic Safety Administration, W41-326
U.S. Department of Transportation
1200 New Jersey Avenue SE
Washington, DC 20590
If you want to talk to someone at NHTSA about what a request for interpretation should include, call the Office of the Chief Counsel at 202-366-2992.
Please note that NHTSA’s response will be made available in this online database, and that the incoming interpretation request may also be made publicly available.