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: aiam5151OpenMr. Patrick P. Radice Director of Operations Electronics Division Tridon 101 Evergreen Drive Springfield, TN 37172; Mr. Patrick P. Radice Director of Operations Electronics Division Tridon 101 Evergreen Drive Springfield TN 37172; "Dear Mr. Radice: We have received your undated letter with respect t certification of aftermarket flashers. You understand that manufacturers of aftermarket turn signal flashers and hazard warning signal flashers must certify that the flashers comply with the applicable requirements of Federal Motor Vehicle Safety Standard No. 108 prior to sale. However, when a vehicle is equipped with a combination turn signal/hazard warning signal flasher, you ask whether the manufacturer of the replacement flasher must certify compliance with requirements for both flashers, or can certify the flasher to 'meet either the turn signal flasher or hazard warning signal flasher of FMVSS-108 but not both?' Paragraph S5.8.1 (formerly S5.7.1) of Standard No. 108 requires that each item of lighting equipment manufactured to replace any item of lighting equipment on any vehicle to which Standard No. 108 applies shall be designed to conform to Standard No. 108. Therefore, a combination turn signal/hazard warning signal flasher that is manufactured to replace a combination turn signal/hazard warning signal flasher must be designed to conform to requirements applicable to both turn signal flashers and hazard warning signal flashers. Paragraph S5.8.2 permits replacement lighting equipment to be labelled with the symbol DOT, constituting a certification of compliance to applicable Federal motor vehicle safety standards (although the manufacturer may certify by a label or tag affixed to the flasher or the container in which it is shipped). The 'applicable Federal motor vehicle safety standards' for a combination turn signal/hazard warning signal flasher are those portions of Standard No. 108 that specify requirements for turn signal flashers and hazard warning signal flashers. The manufacturer's certification must therefore cover both. I hope this explains the matter for you. Sincerely, John Womack Acting Chief Counsel"; |
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ID: aiam4865OpenMr. Richard F. Land Bureau of Manpower and Facilities Tennessee Department of Health and Environment 287 Plus Park Blvd. Nashville, TN 37247-0701; Mr. Richard F. Land Bureau of Manpower and Facilities Tennessee Department of Health and Environment 287 Plus Park Blvd. Nashville TN 37247-0701; "Dear Mr. Land: This responds to your February 12, 1991 letter to Ms Fujita of my staff concerning the ambulance fleet you recently inspected. Each ambulance had a wooden block mounted under the accelerator pedal to limit the driver's ability to accelerate the vehicle. You state that Tennessee law does not prohibit installation of these 'makeshift speed governors.' However, you would like to know whether NHTSA's requirements would prohibit installation of the blocks. The answer to your question is no. In a March 26 telephone conversation with Ms. Fujita, you said that the blocks were installed by the ambulance owner. Our standards do not regulate in any manner how a vehicle owner can modify his or her vehicle. If the blocks were installed by a motor vehicle manufacturer, distributor, dealer or repair business, certain requirements of the Vehicle Safety Act (copy enclosed) would apply. Section 108(a)(2)(A) of the Act prohibits any person in the aforementioned categories from knowingly 'render ing inoperative' any equipment or element of design installed in compliance with an FMVSS. However, there would be no rendering inoperative of compliance with the FMVSS for accelerator control systems (FMVSS 124) in the situation you described, because that FMVSS does not establish requirements for accelerator pedal actuation. Of course, the installation of the block must not have rendered inoperative compliant equipment or designs on the vehicle that were installed pursuant to other safety standards. For example, the block must not interfere with the vehicle's braking ability. I hope this information is helpful. Please contact us if you have further questions. Sincerely, Paul Jackson Rice Chief Counsel Enclosure"; |
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ID: aiam0864OpenMr. W. G. Milby, Project Engineer, Blue Bird Body Company, Fort Valley, GA, 31030; Mr. W. G. Milby Project Engineer Blue Bird Body Company Fort Valley GA 31030; Dear Mr. Milby: This is in reply to your letter of August 10, 1972, concerning th application of Motor Vehicle Safety Standard No. 302, 'Flammability of Interior Materials', to shower curtains in the motor homes you manufacture. You ask whether the NHTSA would consider it 'acceptable' for you not to supply a shower curtain with the motor homes you equip with showers.; You have the right, under the Vehicle Safety Act, to sell a motor hom with equipment omitted, as long as the equipment is not required by a safety standard or necessary for the safe functioning of the vehicle. Naturally, we would prefer that you fully equip the vehicle with a conforming curtain, but we cannot force you to do so.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam3940OpenMr. T. Chikada, Manager, Automotive Lighting, Engineering Control Department, Stanley Electric Co., Ltd., 2-9-13, Nakameguro, Meguro-ku, Tokyo 153, Japan; Mr. T. Chikada Manager Automotive Lighting Engineering Control Department Stanley Electric Co. Ltd. 2-9-13 Nakameguro Meguro-ku Tokyo 153 Japan; Dear Mr. Chikada: This responds to your recent letter to this office seeking a interpretation of the requirements of Standard No. 302, *Flammability of Interior Materials* (49 CFR S571.302). Specifically, you asked whether center high-mounted stop lamps are required to comply with the flammability requirements of Standard No. 302. They are not required to do so.; Section S4.1 of Standard No. 302 lists all the components in ne vehicles which are required to comply with the flammability requirements of the standard. The only item on the list in section S4.1 which might conceivably apply to center high-mounted stop lamps is 'any other interior materials, including padding and crash-deployed elements, that are designed to absorb energy on contact by occupants in the event of a crash.' Assuming that your center high-mounted stop lamps are not designed to absorb energy on contact by an occupant, they would not be required to comply with the requirements of Standard No. 302.; Although interior lights are not required to comply with th requirements of Standard No. 302, the agency has noted that almost all such lights now in production use fire-resistant plastic lenses and fixtures. Liability might be found under State and common law if the newly required center high-mounted stop lamps were to incorporate highly flammable plastic components, while the other interior lights incorporated fire-resistant plastic components.; Please do not hesitate to contact me if you have any further question in this area.; Sincerely, Jeffrey R. Miller, Chief Counsel |
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ID: aiam5245OpenMr. Thomas Dougherty C.A.P.S. Inc. 1712 Rudder Industrial Park Drive Fenton, MO 63026; Mr. Thomas Dougherty C.A.P.S. Inc. 1712 Rudder Industrial Park Drive Fenton MO 63026; "Dear Mr. Dougherty: This responds to your letter asking about how thi agency's regulations might apply to your product, the 'E.A.R.S.' system. You state that your product contains an LED light and an 82 decibel tone and serves to alert hearing impaired drivers of approaching emergency vehicles. You further state that the part of the system that alerts drivers plugs into the cigarette lighter, while a microphone is placed outside the vehicle. (You did not explain how or where the microphone is placed or whether a hole is drilled through the windshield.) I am pleased to have this opportunity to explain our regulations. I am also enclosing a copy of a fact sheet titled 'Information for New Manufacturers of Motor Vehicles and Motor Vehicle Equipment.' By way of background information, the National Highway Traffic Safety Administration (NHTSA) is authorized to issue Federal motor vehicle safety standards (FMVSS's) for new motor vehicles and new items of motor vehicle equipment. Section 102(4) of the National Traffic and Motor Vehicle Safety Act (the 'Safety Act') defines, in relevant part, the term 'motor vehicle equipment' as: any system, part, or component of a motor vehicle as originally manufactured or any similar part or component manufactured or sold for replacement or improvement of such system, part, or component or as any accessory, or addition to the motor vehicle ... (emphasis added). In determining whether an item of equipment is considered an accessory, NHTSA applies two criteria. The first criterion is whether a substantial portion of the expected use of the item is related to the operation or maintenance of motor vehicles. We determine a product's expected use by considering product advertising, product labeling, and the type of store that retails the product, as well as available information about the actual use of the product. The second criterion is whether the product is intended to be used principally by ordinary users of motor vehicles. If the product satisfies both criteria, then the product is considered to be an 'accessory' and thus is subject to the provisions of the Safety Act. Applying these criteria to the E.A.R.S. system, it appears that this product would be an accessory and thus an item of motor vehicle equipment under the Safety Act. Based on our understanding of the product, it appears that the entire portion of the expected use of the E.A.R.S system relates to motor vehicle operation. That is, the system is intended to alert the vehicle driver about an oncoming emergency vehicle. Also, it appears that the product would typically be used by ordinary users of motor vehicles, in particular, hearing impaired drivers. While it appears that the E.A.R.S. system is an item of motor vehicle equipment, NHTSA has not issued any standards for such a device. Nevertheless, there are other Federal laws that indirectly affect the manufacture and sale of your product. You as the product's manufacturer are subject to the requirements in sections 151-159 of the Safety Act concerning the recall and remedy of products with defects related to motor vehicle safety. In the event that the manufacturer or NHTSA determines that the product contains a safety related defect, the manufacturer would be responsible for notifying purchasers of the defective equipment and remedying the problem free of charge. A commercial business that installs the E.A.R.S. system would also be subject to provisions of the Safety Act that affect modifications of new or used vehicles. Section 108(a)(2)(A) of the Safety Act (15 U.S.C. 1397(a)(2)(A)) provides that: No manufacturer, distributor, dealer, or motor vehicle repair business shall knowingly render inoperative, in whole or in part, any device or element of design installed on or in a motor vehicle ... in compliance with an applicable Federal motor vehicle safety standard. This means that a manufacturer, distributor, dealer, or motor vehicle repair business must not install your device if the system renders inoperative the vehicle's compliance with the FMVSS's. For instance, compliance with Standard No. 205 might be degraded if it were necessary to drill a hole through the windshield. Any violation of this 'render inoperative' prohibition would subject the violator to a potential civil penalty of up to $1,000 for each violation. Please note also that the render inoperative prohibition does not apply to modifications that vehicle owners make to their own vehicles. Thus, Federal law would not apply in situations where individual vehicle owners install the E.A.R.S. system in their own vehicles, even if the installation were to result in the vehicle no longer complying with the safety standards. However, NHTSA encourages vehicle owners not to degrade any safety device or system installed in their vehicles. In addition, individual States have the authority to regulate modifications that individual vehicle owners may make to their vehicles, so you might wish to consult State regulations to see whether your device would be permitted. I hope this information is helpful. If you have any further questions about NHTSA's safety standards, please feel free to contact Marvin Shaw of my staff at this address or by telephone at (202) 366-2992. Sincerely, John Womack Acting Chief Counsel Enclosure"; |
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ID: aiam1354OpenMr. Jack R. Gilstrap, Southern California Rapid Transit District, 1060 South Broadway, Los Angeles, CA 90015; Mr. Jack R. Gilstrap Southern California Rapid Transit District 1060 South Broadway Los Angeles CA 90015; Dear Mr. Gilstrap: We are enclosing an Experimental Device Permit authorizing you to equi the buses described in your letter of December 11 with a warning system which will flash the clearance and sidemarker lamps in the event of an emergency. The permit will expire on December 31, 1974.; Please supply us with the data on the number and types of crime involving your buses during the calendar years 1972 and 1973. This information can later be compared with that of similar periods during 1974 when the buses are equipped with the experimental lamps. We would also like to have a copy of the outline of your plan for evaluating the effectiveness of the new system.; A copy of the drawing or wiring diagram of the installation would als be of interest to us, particularly the safeguards taken against the possibility of inadvertent activation.; Very truly yours, Warren M. Heath, Commander, Engineering Section |
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ID: aiam0605OpenMr. Louis Goldberg, Product Manager - Industrial Mastics, Daubert Chemical Company, 709 Enterprise Drive, Oak Brook, IL, 60521; Mr. Louis Goldberg Product Manager - Industrial Mastics Daubert Chemical Company 709 Enterprise Drive Oak Brook IL 60521; Dear Mr. Goldberg: This is in reply to your letter of February 14, 1972, concerning th application of Motor Vehicle Safety Standard No. 302, 'Flammability of Interior Materials,' to industrial deadeners and underbody coatings that you manufacture for use in motor vehicles. You describe three uses of these products: as an undercoating, a deadener, and an adhesive, and enclose three brochures, each describing a different product.; Standard No. 302 applies to motor vehicles, and from a lega standpoint, manufacturers of component parts are not subject to its requirements. As the completed vehicle must comply with the standard, however, vehicle manufacturers, on whom the burden of compliance does rest, must ascertain that components they use in their vehicles do meet the standard's requirements.; In this context, and with reference to your products, paragraph S4.2 o the standard (copy enclosed), requires that certain portions of vehicle components, including composites consisting of both surface and underlying materials, meet the specified burn-rate requirements. (A notice of proposed rulemaking, published May 25, 1971, also enclosed, would modify to some degree this provision.) Where composites are involved, compounds used between the layers of the composite are required to meet the requirements as part of the composite. Thus, while we cannot make an exact determination from the general descriptions in your letter, it is quite possible that when your products are used as deadeners or adhesives they would appear in composites that are required to meet the standard. Whether the material actually comes into contact with passengers is not a criterion.; At the same time, under the standard only completed vehicles will b tested. We note from the brochures you have enclosed that your materials are not flammable after drying. If this is the case, you should not have a problem with conformity, as your material will be tested, where appropriate, in what we would assume would be its dry state.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam1601OpenMr. M. J. Denholm, Director of Engineering, Power Controls Division, Midland-Ross Corporation, 490 So. Chestnut Street, Owosso, MI 48867; Mr. M. J. Denholm Director of Engineering Power Controls Division Midland-Ross Corporation 490 So. Chestnut Street Owosso MI 48867; Dear Mr. Denholm: This responds to Midland-Ross' February 8, 1974, petition for a amendment of S5.1.2.1 and S5.2.1.2 of Standard No. 121, *Air brake systems*, to establish separate air reservoir volume requirements for several brake chamber types generally available in the air brake component market.; The standard presently requires air reservoir volumes to be a multipl of the vehicle's brake chamber volumes. Midland-Ross also requested that S5.1.2.2 and S5.2.1.3 be amended to require that a reservoir withstand hydrostatic pressure five times greater than stated on its label without rupture, or permanent circumferential deformation exceeding one percent. The standard presently requires that an air reservoir withstand internal hydrostatic pressure of five times the vehicle compressor cutout pressure or 500 pounds, whichever is greater. The petition also requests modifications of the trailer test rig, which were made in a recent amendment of the standard (29 FR 17563, May 17, 1974).; You suggested that our requirement for air reservoir volume as multiple of brake chamber volume will encourage installation of smaller equipment and thereby create a safety problem. We cannot agree, in view of the standard's stopping distance requirements which in effect mandate the installation of high performance components. Indications to date are that manufacturers have in fact not reduced brake chamber volumes. A certain degree of chamber stroke standardization may occur, which the NHTSA views as favorable. For these reasons your request is denied.; With regard to the air reservoir pressure requirements of S5.1.2.2 an S5.2.1.3, you argued that a reservoir manufacturer is unable to establish the required strength of his product because he cannot control the compressor cutout pressure of the vehicle on which the reservoir is installed. It should be understood that the standard is not an equipment standard with which Midland-Ross must comply, but a vehicle standard with which the vehicle manufacturer must comply. We have determined that the reservoir should be designed to manage the pressures to which it might be exposed on the vehicle on which it is installed. The vehicle manufacturer is able to establish a compressor cutout pressure (on powered vehicles) and, based on that value, order the appropriate reservoir to meet the requirement. It is evident that commercial considerations will standardize compressor cutout pressures on a reasonable range of available reservoir strengths. Midland-Ross as a manufacturer of reservoirs is free to establish a range of reservoir strengths, and label the reservoirs as described in your petition. For the reasons cited, however, your petition to mandate this is denied.; We agree the requirement that a reservoir 'withstand' a certai pressure can be further specified, and we are considering a proposal to do this in the future. At this time the NHTSA has adopted the SAE Standard No. J10a, which specifies that there be no rupture or permanent circumferential deformation exceeding one percent.; Sincerely, James B. Gregory, Administrator |
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ID: aiam5185OpenMr. Daniel L. Kokal Champagne Imports 506 Stonehurst Court Gainesville, VA 22065; Mr. Daniel L. Kokal Champagne Imports 506 Stonehurst Court Gainesville VA 22065; "Dear Mr. Kokal: This is in reply to your letter of May 8, 1993 requesting use of continuous surety bonding for importation of nonconforming vehicles under the Registered Importer program. As you have informed us, ' c urrently, single entry bonds are filed with each nonconforming vehicle at 150% of the vehicle's value . . . .', and that this is expensive for the importer of Canadian vehicles which 'rarely, if ever, require safety modifications to meet U.S. standards.' You propose a continuous bond which would cover more than one vehicle, with the same level of value. The example you give is that of a continuous bond of $150,000 which would cover 10 vehicles imported together, each with a value of $10,000 as determined by the U.S. Customs Service, rather than individual bonds for 10 vehicles of $10,000 value, each bond at $15,000. Your specific suggestion is for 'the ability to import no more than 15 vehicles under a given continuous bond at 150% total vehicle value.' We are unable to implement your suggestion at present. Under 49 CFR 591.8(a), the safety compliance bond's coverage is restricted to 'only one motor vehicle.' Thus, rulemaking is required to amend paragraph 591.8(a) to permit a bond that covers more than one vehicle. In addition, Appendix A to Part 591 will have to be modified, this sets forth the terms of the bond, presently expressed in single-entry terms. As NHTSA is required to reimburse Customs for its costs in processing safety compliance bonds, that agency must necessarily be consulted to determine the impact of such a change on its operations, with a possible change in the bond processing fee imposed under Part 594. However, the Office of Vehicle Safety Compliance will consider the feasibility of rulemaking on this subject. Sincerely, John Womack Acting Chief Counsel "; |
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ID: aiam0388OpenDr. Arnold J. Holland, Triplex Safety Glass Co. Ltd., King's Norton (sic) Birmingham B38 8SR, England; Dr. Arnold J. Holland Triplex Safety Glass Co. Ltd. King's Norton (sic) Birmingham B38 8SR England; Dear Doctor Holland: This is in reply to your letters of June 18 and 21, 1971, concernin the application of the proposed requirements for glazing materials (Docket 71-1, Notice 1) as they would apply to heated rear windows and mirrors.; In your letter of June 18 you state that the heating lines used in th rear window continue almost to the bottom of the glass at the ends. You propose putting an abbreviated mark at the bottom left hand corner, with the full trade mark appearing at the bottom center, and ask whether this would comply with the proposed requirements. The answer to this question is no. Paragraph S5.5 of the proposed amendment would require the complete mark to be placed in either the lower left or right hand corner of the rear window.; Your letter of June 21 asks whether it is likely that there will b further amendment to Standard No. 205. You mention that you were told that the proposed amendment should have referred to interior vanity mirrors and not the normal rear view mirror. Finally, you state that if the proposed requirements apply to the normal rear view mirror, you will need to do additional development work.; The proposed amendment to Standard No. 205 is still unde consideration, and no final determination has been made as to whether the proposal, or any part of it, will be issued as a final rule. With reference to your comments concerning the normal rear view mirror, S4.3 of the proposal clearly refers to glazing for use in all interior mirrors, including both the normal rear view mirror, and any other interior mirror, such as a vanity mirror. With reference to your comments concerning the need for additional development work, adequate lead times will be provided for in any final rule that is issued.; Copies of your letters will be placed in Docket No. 71-1. Sincerely, Clue D. Ferguson, Director, Office of Crashworthiness, Moto Vehicle Programs; |
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.