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: aiam2415OpenMr. Ronald W. Cooke, Engineering Manager, E. Edelmann & Co., Route 38, Airport Industrial Park, Dixon, IL 61021; Mr. Ronald W. Cooke Engineering Manager E. Edelmann & Co. Route 38 Airport Industrial Park Dixon IL 61021; Dear Mr. Cooke: Thank you for your letter of August 19, 1976, to Dr. James B. Gregory requesting information on aftermarket gas caps as they relate to compliance with Federal Motor Vehicle Safety Standard (FMVSS), No. 301. Your inquiry has been forwarded to this office for reply. Apparently your letter of May 26, 1976, was either lost or misdirected, as we can find no record of it in our files, and we sincerely apologize for this delay in responding to your inquiry.; The National Highway Traffic Safety Administration does not regulat vehicle fuel tank caps as such, however, FMVSS No. 301, Fuel System Integrity, specifies performance requirements to assure the integrity of the entire vehicle fuel system (which includes the fuel tank cap) in various crash modes.; Thus, if installation of your replacement cap is accomplished prior t the first purchase of the vehicle for purposes other than resale causing the vehicle's fuel system not to be in compliance with the applicable safety standard, the person installing the cap or offering the vehicle for sale would be in violation of S108(a)(1) of the National Traffic and Motor Vehicle Safety Act (Pub. L. 89-503). That would make the installer or seller subject to civil penalties of up to $1,000 for each violation.; Recent amendments to the Traffic Safety Act (Pub. L. 932-492) prohibi any manufacturer, distributor, dealer, or motor vehicle repair business from knowingly rendering inoperative, in whole or in 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 motor vehicle safety standard (S108(a)(2)(A)). Thus, it is illegal for any of the above named persons to install a fuel tank cap that he knows will cause the vehicle to be in non-compliance with the fuel system integrity standard. Federal Law does not, however, prohibit the owner of a vehicle from purchasing and installing a fuel tank cap of his choice on his own vehicle, even though he may compromise the Fuel System Integrity Standard.; We are interested in any information regarding safety problem associated with replacement gas caps as a basis for further action. If you could provide any such information, we would be most grateful.; Thank you for sharing your thoughts with us. Sincerely, Robert L. Carter, Associate Administrator, Motor Vehicl Programs; |
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ID: aiam0428OpenMr. William H. Lawson, Jr., Manager, Market Development, Sierracin Corporation, 12780 San Fernando Road, Sylmar, CA 91342; Mr. William H. Lawson Jr. Manager Market Development Sierracin Corporation 12780 San Fernando Road Sylmar CA 91342; Dear Mr. Lawson: This is in reply to your letter of August 4, 1971, in which yo enclosed a copy of the manufacturer's symbol that would be used to identify windshields manufactured by the Sierracin Corporation, and ask whether the symbol is acceptable as illustrated. You also request our comments on requirements for the label location on the product.; The symbol you have enclosed complies with Motor Vehicle Safet Standard No. 205, 'Glazing Materials' and, except for the omission of a hyphen between the 'DOT' symbol and the manufacturer's code mark, also with the marking requirements proposed in the notice of January 9, 1971 (36 F.R. 326), which would amend certain provisions of the standard. We would consider this deviation to be inconsequential.; With reference to location requirements, the present standard does no specify a location for the windshield marking. The proposed amendment, which is still under consideration, would require the mark to be placed in the lower left hand corner of the windshield.; Sincerely, Lawrence R. Schneider, Acting Chief Counsel |
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ID: aiam2100OpenMr. Chester Mercer, Jr., Mercer Machine & Hydraulics, Inc., 13060 Butler Street, Redding, Pennsylvania 19601; Mr. Chester Mercer Jr. Mercer Machine & Hydraulics Inc. 13060 Butler Street Redding Pennsylvania 19601; Dear Mr. Mercer: #I am writing to confirm your October 17, 1975 telephone conversation with Mark Schwimmer of this office concerning the requirements of Federal Motor Vehicle Safety Standard No. 106-74, *Brake Hoses*. I understand that your company manufactures, from hose and end fittings supplied by other manufacturers, hydraulic brake hose assemblies for use in motor vehicles. #For your convenience, I am enclosing a copy of the standard (including two recent Federal Register notices) and an information sheet entitled 'Where to Obtain Motor Vehicle Safety Standards and regulations.' #The standard specifies performance and labeling requirements for brake hose, end fittings, and brake hose assemblies. As an assembly manufacturer, you must certify that your assemblies comply with the standard by affixing a band as set out in S5.2.4. A designation of your choice should identify you as the assembler. You need register this designation with the NHTSA only once, even if you also manufacture air brake hose assemblies. #While the standard generally requires assemblies to be manufactured from conforming hose and end fittings, an exception (set out in S12.) permits the use of hose and fittings which meet the performance requirements but not the labeling requirements, until August 31, 1976. (The labeling requirements for hose and fittings became effective September 1, 1974, this exception is designed to facilitate the depletion of inventories of such components manufactured before that date.) #The standard does not specify the testing which you must do, it does specify the performance levels which assemblies must meet when tested by the NHTSA for compliance. The National Traffic and Motor Vehicle Safety Act of 1966, as amended, requires you to conduct a notification and remedy campaign with respect to noncomplying assemblies. You are also subject to a civil penalty of up to $1,000 for each noncomplying assembly ( not to exceed $800,000 for each related series of noncompliances). The amount of testing which you perform has no effect on your notification and remedy obligations. If, however, you did exercise due care, you are not liable for the civil penalty. 'Due care' is a flexible concept. It is evaluated on a case-by-case basis, taking into consideration the size of your company, the amount of testing you perform, and other factors. #Yours truly, Richard B. Dyson, Assistant Chief Counsel; |
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ID: aiam5295OpenCheryl Graham, District Manager Northeast Region ARI P.O. Box 5039 Mt. Laurel, NJ 08054; Cheryl Graham District Manager Northeast Region ARI P.O. Box 5039 Mt. Laurel NJ 08054; "Dear Ms. Graham: We have received your letter of November 10, 1993 asking about the permissibility of aftermarket installation of an auxiliary pair of stop lamps 'at each side of the rear window.' By way of background information the National Highway Traffic Safety Administration (NHTSA) issues Federal motor vehicle safety standards under the authority of the National Traffic and Motor Vehicle Safety Act (Safety Act). Under that Act, the sole restraint upon modifications to vehicles in use is that, if performed by a manufacturer, distributor, dealer, or motor vehicle repair business, the modifications must not 'knowingly render inoperative, in whole or in part, any device or element of design installed on . . . a motor vehicle in compliance with an applicable Federal motor vehicle safety standard . . . .' (15 U.S.C. 1397(a)(2)(A)). In NHTSA's view, if the modifications tend to impair the safety effectiveness of the 'device or element of design', then, at the minimum, a partial inoperability may have occurred within the meaning of the statutory prohibition. The question raised by your letter, therefore, is whether the installation of the auxiliary stop lamps in that location would impair the effectiveness of the three original equipment stop lamps. NHTSA decided to require the center highmounted stop lamp in addition to the then-existing original equipment two-lamp stop lamp system following research which indicated that a three-lamp system of this configuration was demonstrably more effective in preventing rear end crashes than other rear end lighting systems that were tested, and considerably lower in cost. Included in the testing was a four-lamp system which incorporated two lamps at each side of the rear window, but no tests were conducted on the five-lamp system you describe. The reasons for the better performance of the three-lamp system are unclear, but the triangular lighting array proved to be more effective than the trapezoidal four-lamp system (and more effective than a system tested which separated the usual stop lamp from the taillamp). Your customer appears to believe that the ability of following drivers to avoid rear end crashes is enhanced by a five-lamp stop lamp system. On the other hand, your proposed system, by incorporating the two lamps at each side of the rear window, would appear to change the lighting array. We cannot say that the five-lamp system would either enhance or detract from safety. Thus, we cannot find that the additional lamps would 'render inoperative' the original equipment three-lamp system, and it would be permissible under the regulations of this agency. However, the permissibility of such a modification would be determinable under State law. We are unable to advise you on the laws of the various States and suggest that you write the American Association of Motor Vehicle Administrators for an interpretation. Its address is 4600 Wilson Boulevard, Arlington, VA 22203. You have also asked 'if the work is done improperly and results in an accident, where does the liability lie?' This question is a matter of state law, and we suggest that you consult a local attorney concerning it. Sincerely, John Womack Acting Chief Counsel"; |
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ID: aiam2550OpenMr. Robert B. Kurre, Director of Engineering, Wayne Corporation, P. O. Box 1447, Industries Road, Richmond, IN 47374; Mr. Robert B. Kurre Director of Engineering Wayne Corporation P. O. Box 1447 Industries Road Richmond IN 47374; Dear Mr. Kurre: This responds to your December 10, 1976, petition to amend Standard No 222, *School Bus Passenger Seating and Crash Protection*. In your petition you request that the NHTSA withdraw the requirements for seat belts in buses with gross vehicle weight ratings (GVWR) of 10,000 pounds or less. Secondly, you suggest that the NHTSA reconsider the validity of establishing 10,000 pounds GVWR as the dividing line between buses that must be equipped with seat belts and those which need not be so equipped. The NHTSA denies your requested rulemaking.; The NHTSA mandated the installation of seat belts in school buses wit GVWR's of 10,000 pounds or less, because these vehicles are subject to different crash pulses than larger school buses under the same accident circumstances. To ensure adequate protection for children transported in these vehicles, the NHTSA applied to small school buses some of the seating requirements mandated for larger buses plus the installation of seat belts. Since we are aware of no data indicating that small buses do not need the additional protection provided by seat belts, the NHTSA considers the provision of seat belts in these school buses to be a necessary safety requirement.; The second recommendation in your petition suggests that the NHTS classification of vehicles into two groups, one with GVWR's of 10,000 pounds or less and another with GVWR's greater than 10,000 pounds, is arbitrary. You indicate that a vehicle weighing slightly more than 10,000 pounds will not react in a crash situation significantly different than a vehicle slightly under 10,000 pounds. Accordingly, you suggest that there is no valid reason to have different requirements for buses within a relatively narrow weight range.; The NHTSA has historically classified vehicles into the two weigh groupings you mention. This has been done in part because there are significant differences between large and small vehicles with respect to their reactions in crashes. The agency realizes that any line differentiating the two classes may seem arbitrary to manufacturers of vehicles that fall barely on either side of the line. Arguably, these vehicles, similar in many respects, would exhibit only minor differences in crash pulse in any given accident situation. Nonetheless, the classification is valid for the majority of vehicles in each class. Since we are aware of no data that would indicate that a line could better be drawn elsewhere, the NHTSA has decided to retain the present classification.; Sincerely, Robert L. Carter, Associate Administrator, Motor Vehicl Programs; |
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ID: aiam0097OpenMr. Toyotaro Yamada, Manager, Toyota Motor Company, Limited, 231 Johnson Avenue, Newark, NJ 07108; Mr. Toyotaro Yamada Manager Toyota Motor Company Limited 231 Johnson Avenue Newark NJ 07108; Dear Mr. Yamada: Thank you for your letter of July 23, 1968, to Mr. George C. Nield Acting Director, Motor Vehicle Safety Performance Service, concerning the requirements for turn signal and hazard warning signal flashers as specified by Motor Vehicle Safety Standard No. 108.; With certain exceptions, paragraph S3.3 of Standard No. 108 permits th use of combination lamps, reflective devices and items of associated equipment, provided the requirements for each lamp, reflective device and item of associated equipment are met. Therefore, a combination turn signal and hazard warning signal flasher may be used, provided the requirements for each signal (turn and hazard warning) are met.; You are correct in your understanding that Standard No. 108 an basically referenced SAE Standards J590 and J945 do not require operation of the flasher unit with only one signal bulb in the test circuit. The standard test circuit shown in Figure I of SAE Standard J823 indicates a minimum of two signal lamps and one pilot indicator lamp as the lamp load.; Thank you for writing. Sincerely, David A. Fay, Office of Standards on Accident Avoidance Motor Vehicle Safety Performance Service; |
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ID: aiam3711OpenMr. Koji Tokunaga, Manager of Engineering, Isuzu Motors America, Inc., 21415 Civic Center Drive, Southfield, MI 48076; Mr. Koji Tokunaga Manager of Engineering Isuzu Motors America Inc. 21415 Civic Center Drive Southfield MI 48076; Dear Mr. Tokunaga: This responds to your letter of May 26, 1983, asking whether continuous loop seat belt system you are considering would comply with the requirements of Safety Standard No. 208, *Occupant Crash Protection*.; Continuous seat belt systems are permissible under Safety Standard No 208 if certain conditions are met. Paragraph S7.1.1 of that standard requires adjustment of the lap belt portion of Type 2 belts 'by means of an emergency locking or automatic-locking retractor' and adjustment in most cases of the upper torso portion 'by means of an emergency-locking retractor.' The language permits some single retractor, continuous loop systems if the single retractor does 'automatically adjust' the tension of the lap belt portion to prevent excessive slack. Because of the danger of submarining due to a slack lap belt, the agency has restricted the acceptability of continuous loop systems under S7.1.1.; To conform to the requirements, the buckle of the assembly must b designed by the manufacturer with a sufficiently low level of friction to qualify the lap portion as automatically adjusting. This means that when the belt is buckled by the vehicle occupant, the retractor must be capable of cinching the lap belt tightly around the occupants, pelvic area (regardless of where the buckle tongue is located along the belt webbing when the belt is fastened). The friction in the buckle tongue cannot be so high that the occupant must manually pull the belt webbing through the tongue to tighten the lap belt.; We note your statement that the one-way frictional bar included in you contemplated belt design 'permits the wearer to fasten the lap belt more tightly than the tension from the ELR usually achieves.' This is certainly permissible, provided the ELR does tighten the belt sufficiently for the lap belt to be considered automatically adjustable. You will have to make this determination, however. Please note that it is the manufacturer's responsibility to determine whether or not its belt design complies with the standard. The agency does not offer advance approval of any motor vehicle or piece of motor vehicle equipment. Further, the agency does not make determination of compliance of a vehicle or item of equipment prior to the manufacturer's certification of that vehicle or equipment.; I hope this clarification will be of help to you in your design plans. Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam2803OpenRobert H. J. Loftus, The Barbour House, 4069 Chain Bridge Road, Fairfax, VA 22030; Robert H. J. Loftus The Barbour House 4069 Chain Bridge Road Fairfax VA 22030; Dear Mr. Loftus: This responds to your January 12, 1978, letter asking several question concerning the applicability of the Federal safety standards to vehicles that are being reconstructed with new chassis. The answers to your specific questions are set forth below.; 1. You ask whether the replacement of the engine, transmission, driv train, rear end, frame, front axle, front brakes, wheels and steering box constitutes the manufacture of a new chassis requiring a new or upgraded body. The answer to your question is yes. Part 571.7(e) of Volume 49 of the Code of Federal Regulations specifies the items that must be retained in a truck chassis in order that such chassis be considered used. These same considerations apply to reconstructed school buses since they are built on truck chassis.; 2. You ask what parts of a chassis must be retained to ensure that th vehicle could continue to utilize an old body that does not comply with current Federal safety standards. Part 571.7(e) states that, at a minimum, the engine, transmission, and drive axle(s) must be retained.; 3. You ask who must certify a remanufactured vehicle if its chassis i considered old or new. In the case of an old chassis that retains the required components and is therefore considered used, no certification is required of any repair business. In the case of a remanufactured chassis, the chassis manufacturer must certify his chassis for compliance and the shop that installs the body must certify the final compliance of the vehicle.; 4. Part 568.8 states that vehicles altered before the first purchas for purposes other than resale must be labeled with an alterer's label. When a new chassis is installed in a vehicle, this is not an alteration, but rather, it is the manufacture of a new motor vehicle. Therefore, section 568.8 would not apply. The other provisions of Part 568 relating to the manufacture of a new motor vehicle would apply to this reconstructed vehicle. The person undertaking the remanufacture would be treated like the original manufacturer of the vehicle and would be required to certify it for compliance with the standards.; 5. Standards promulgated after 1975 that are specifically applicable t school buses are : Standard No. 217-76, *Bus Window Retention and Release*, Standard No. 220, *School Bus Rollover Protection*, Standard No. 222, *School Bus Body Joint Strength*, Standard No. 222, *School Bus Passenger Seating and Crash Protection*, and Standard No. 301-75, *Fuel System Integrity*. Many of the other safety standards apply to school buses as well as other vehicles. I am enclosing a sheet detailing the applicability of Federal safety standards. All Federal safety standards are located in Volume 49 of the Code of Federal Regulations, Part 571. By examining the standards in Part 571, you can ascertain when their most recent amendment has occurred.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam3341OpenMr. H. Miyazawa, Director, Automotive Lighting, Engineering Department, Stanley Electric Co., Ltd., 2-9-13, Nakameguro, Meguro-ku, Tokyo 153, Japan; Mr. H. Miyazawa Director Automotive Lighting Engineering Department Stanley Electric Co. Ltd. 2-9-13 Nakameguro Meguro-ku Tokyo 153 Japan; Dear Mr. Miyazawa: This responds to your August 4, 1980, letter asking whether severa vehicle components would be required to comply with Standard No. 302, *Flammability of Interior Materials*. In particular you ask whether a headlining lamp, a courtesy lamp installed on a door panel, or various pilot indicator lamps and meters installed in the front panel must comply with the requirements.; As you stated in your letter, Section S4.1 of the Standard lists th components required to comply with the standard. Further, that section states that materials designed to absorb energy on contact by occupants must comply with the standard. Since the components that you mention are not listed in S4.1 and since they do not appear to be designed to absorb energy on contact by an occupant, we conclude that they are not required to comply with the standard.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam4484OpenMr. Ernie J. Bunnell Vice President/General Manager Pacific T-Top, Inc. l5241 Transistor Lane Huntington Beach, CA 92649; Mr. Ernie J. Bunnell Vice President/General Manager Pacific T-Top Inc. l5241 Transistor Lane Huntington Beach CA 92649; Dear Mr. Bunnell: This is in reply to your letter of August 30, 1988 to Taylor Vinson of this Office. You have provided diagrams of two types of deck lid spoiler installations, intended as either OEM or aftermarket equipment, and have asked how these relate to requirements for the center highmounted stop lamp. You understand that the spoiler itself does not have to meet the lighting standard, but would like to comply if possible. You are correct that the spoiler itself is not subject to the lighting standard (Federal Motor Vehicle Safety Standard No. 108), however, its installation has the potential for creating a noncompliance with that standard. The basic requirements for the lamp is that it must meet the photometric intensities at each of the test points specified in Figure l0 of the standard, and the visibility (and other) requirements of paragraph S4.l.l.41. Photometric testing is conducted according to SAE Recommended Practice J186a, with the photometer at a distance of at least l0 feet from the lamp. Test points lie above and below the horizontal axis of the lamp, and to the left and right of the vertical axis. According to your first design, the spoiler is 'at or below the rear brake light using the 5 degree measurement as a guide.' You are correct in taking into account the necessity of meeting the 5 degree down test points. But compliance will be affected by the location of the lamp and slope of the deck lid as well as the shape of the spoiler. The second spoiler is designed 'to go over the horizontal intensity of the light.' We interpret this as recognition of the need to meet the test points lying 5 and l0 degrees above the horizontal. Our comments are the same as for the first spoiler. In short, if a spoiler design is not vehicle specific there may be no practicable way for you, as the manufacturer of the spoiler, to determine whether its installation would create a noncompliance. If your design is vehicle specific, the SAE photometric test could be conducted with the spoiler installed. The responsibility for compliance with Standard No. 108 is initially that of the vehicle manufacturer. If the spoiler is installed as part of the vehicle manufacturing process, the manufacturer's certification of compliance with all applicable Federal motor vehicle safety standards would cover the center lamp with the spoiler in place. But the dealer also must ensure that a certified vehicle remains in conformance at the time it is delivered to its first purchaser. Therefore, a dealer could be reluctant to install a spoiler that is not vehicle specific in the absence of some showing that it does not create a noncompliance with Standard No. 108. Once the vehicle is sold, the National Traffic and Motor Vehicle Safety Act in effect forbids the dealer, or any motor vehicle repair business, from modifications that affect compliance of equipment installed in accordance with a safety standard. This prohibition, however, does not extend to the vehicle owner, who may modify the vehicle as (s)he wishes, subject to State laws. We are not aware of any State laws that would forbid spoilers of the designs indicated. We have enclosed a copy of paragraph S4.l.l.41 and Figure l0 for your information, and appreciate your interest in learning more about Standard No. 108. Sincerely, Erika Z. Jones Chief Counsel Enclosure; |
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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.