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: aiam0916OpenMr. D. R. Pomeroy, Chief Chemist, Textile Rubber & Chemical Company, 14241 East Alondra Boulevard, La Mirada, CA, 90638; Mr. D. R. Pomeroy Chief Chemist Textile Rubber & Chemical Company 14241 East Alondra Boulevard La Mirada CA 90638; Dear Mr. Pomeroy: This is in response to your letter of November 3, 1972, to our Regiona Administrator, Region IX, San Francisco, California office concerning the test procedures of Federal Motor Vehicle Safety Standard No. 302, 'Flammability of Interior Materials.'; You state that in the test procedure described in paragraph S5.3, yo see 'no room for the bunsen burner to stand' when a carpet specimen 14 inches long is in the center 'of all inside dimensions of the box.' The source of your interpretive difficulty with respect to the test procedure appears to be your assumption that the carpet specimen should be placed in the center 'of all inside dimensions' of the test cabinet. The test procedure only specifies that the specimen be mounted 'in a horizontal position, in the center of the cabinet.'; The standard does not specify a particular means for positioning th bunsen burner tube or for positioning the test specimen above the top of the burner tube, because there are a variety of satisfactory means used for this purpose. The specimen holder should be in the center of the cabinet with the closed end contacting the end of the cabinet.; Since the bunsen burner is used with the air inlet shutoff, it is i effect a 3/8 inch inside diameter tube with a metering valve. There is no reason why such a device, without the bunsen burner base, may not be permanently mounted inside the cabinet for convenience.; You also ask whether bottled propane gas can be substituted for natura gas. The answer to this question is that your choice of what gas to use is a matter within your own discretion. The standard simply specifies that for our compliance testing, the gas supplied to the burner will have 'a flame temperature equivalent to that of natural gas.'; Sincerely, Robert L. Carter, Associate Administrator, Motor Vehicl Programs; |
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ID: aiam3639OpenMr. Bruce Henderson, Automobile Importers of America, Inc., 1735 Jefferson Davis Highway, Suite 1002, Arlington, VA 22202; Mr. Bruce Henderson Automobile Importers of America Inc. 1735 Jefferson Davis Highway Suite 1002 Arlington VA 22202; Dear Mr. Henderson: This responds to your letter asking about the identificatio requirements of FMVSS 101, *Controls and Displays*. You asked whether it is permissible for a manufacturer to identify a certain manual control with the symbol specified by the European Economic Community (EEC) for the cold start control. According to your letter, the control resets injection timing *and* actuates cylinder warming.; By way of background information, the agency does not provide approval of motor vehicles or motor vehicle equipment. The Vehicle Safety Act requires that each manufacturer assure that its products are in compliance with all applicable standards. The following only represents the agency's opinion based on the specific facts provided in your letter.; The answer to your question is yes, since Standard No. 101 does no include any identification requirements applicable to that specific type of control.; Section S5 of Standard No. 101 requires each passenger car manufacture with any control listed in S5.1 or in column 1 of Table I to meet the requirements of the standard for the location, identification and illumination of such control.; Neither section S5.1 nor column 1 of Table I list or include a singl control which operates the *two* functions noted above.; Since Standard No. 101 does not include any identification requirement applicable to that type of control, identification is at the discretion of the manufacturer. It is therefore permissible, under that standard, to identify that type of control with the symbol specified by the EEC.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam1604OpenMr. Harry L. Cuthbert, Chief Engineer, Eagle International Inc., P.O. Box 4119, 2045 Billy Mitchell Blvd., Brownsville, TX 78520; Mr. Harry L. Cuthbert Chief Engineer Eagle International Inc. P.O. Box 4119 2045 Billy Mitchell Blvd. Brownsville TX 78520; Dear Mr. Cuthbert: This responds to your July 16, 1974, request for approval of the Bendi 'dual circuit air brake system' for use on your buses in satisfaction of Standard No. 121, *Air brake systems.* In a subsequent phone call with Mr. Herlihy of this office, you stated that your only concern was whether the standard requires a parking brake system that meets the axle-by axle retardation force requirements of S5.6.1 and the grade holding requirements of S5.6.2.; The National Highway Traffic Safety Administration is unable t 'approve' plans or prototype systems for compliance with a standard in advance, because there is no way to establish that a vehicle so equipped actually meets the requirements until it has been manufactured.; With regard to your specific question, S5.6 states that each vehicl shall have a parking brake system that meets the requirements of S5.6.1 or S5.6.2 at the manufacturer's option. This means that you are free to choose a system which meets either of these requirements but does not meet both.; Yours truly, Richard B. Dyson, Acting Chief Counsel |
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ID: aiam2025OpenMr. H. Ray Cozad, Chief Engineer, Crane & Excavator Division, 1201 Sixth Street Southwest, Cedar Rapids, IA 52406; Mr. H. Ray Cozad Chief Engineer Crane & Excavator Division 1201 Sixth Street Southwest Cedar Rapids IA 52406; Dear Mr. Cozad: This responds to your July 28, 1975, letter asking whether the unloade vehicle weight of a mobile crane carrier would include components that are essential to its specialized function but are not removed for transit purposes. You also suggest alternative wording for a particular exclusion criterion proposed for mobile crane carriers and similar vehicles under Standard No. 121, *Air Brake Systems*.; I have enclosed a copy of a recent notice that amends Standard No. 121 The preamble to the notice deals with the issues you have raised and should make clear to you that vehicle components are not generally considered part of the rated cargo capacity and therefore would not be subtracted from a vehicle's gross vehicle weight rating to determine the unloaded vehicle weight.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam4958OpenMr. Phil Gray Inventor Westech U.S.A. Inc. Airport Road (P.O. Box 629) Franklin County Airport Swanton, VT 05488; Mr. Phil Gray Inventor Westech U.S.A. Inc. Airport Road (P.O. Box 629) Franklin County Airport Swanton VT 05488; "Dear Mr. Gray: This responds to your letter asking how the laws an regulations administered by this agency would apply to a product you have invented. The device is a flexible plastic stalk that reroutes the shoulder belt to improve the shoulder belt fit for children that have outgrown child safety seats. I am pleased to have this chance to explain our laws and regulations to you. The National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1381 et seq., the Safety Act) authorizes this agency to issue motor vehicle safety standards for new motor vehicles and new items of motor vehicle equipment. We have exercised this authority to establish Standard No. 208, Occupant Crash Protection (49 CFR 571.208). This standard requires new motor vehicles to be equipped with safety belts and requires that those belts meet specified fit and comfort requirements, as set forth in S7 of the standard. However, Standard No. 208 does not apply to aftermarket items that seek to alter belt fit and/or comfort. Hence, your company is not required to certify that this product complies with Standard No. 208 before offering the product for sale. In addition, you are not required to get some sort of 'approval' from this agency before offering this product for sale. NHTSA has no authority to 'approve' motor vehicles or motor vehicle equipment, nor do we endorse any commercial products. Instead, the Safety Act establishes a 'self-certification' process under which each manufacturer is responsible for certifying that its products meet all applicable safety standards. As stated above, this product is not subject to any safety standard, so your company does not have to make any certification. Although none of our safety standards directly apply to this product, there are several provisions in the Safety Act that are relevant. Manufacturers of motor vehicle equipment such as your belt positioning device are subject to the requirements in sections 151-159 of the Safety Act (15 U.S.C. 1411-1419) concerning the recall and remedy of products with defects related to motor vehicle safety. Your letter indicated that you were aware of this responsibility and your company would carry out any necessary recalls if problems should become apparent with this device when it is used by the public. In addition, use of your product could be affected by section 108(a)(2)(A) of the Safety Act (15 U.S.C. 1397(a)(2)(A)). That section prohibits manufacturer, distributors, dealers, and repair shops from knowingly 'rendering inoperative,' in whole or in part, any device or element of design installed on or in a vehicle in compliance with an applicable safety standard. There are two elements of design in a vehicle that might be 'rendered inoperative' by the use of your company's belt positioning device. One is the occupant protection afforded by belts that meet the specified fit and comfort requirements. The other element of design that could be rendered inoperative by the use of your belt positioning device is the burn resistance required by Standard No. 302, Flammability of Interior Materials (49 CFR 571.302). The materials used in the interior of vehicles, including the seat belts, seat backs and cushions, trim panels, and headliner must comply with the burn resistance requirements of Standard No. 302 to reduce deaths and injuries in the event of a fire in the vehicle's interior. If your belt positioning device renders inoperative the belt fit and comfort requirements specified in Standard No. 208 or does not comply with burn resistance requirements, it could not be installed in a vehicle by any manufacturer, distributor, dealer, or repair shop. I have enclosed a general information sheet for new manufacturers that gives a thumbnail sketch of NHTSA's regulations and provides information on how to obtain copies of those regulations. I hope that this information is helpful. If you have any further questions or need some additional information, please feel free to contact Steve Kratzke of my staff at this address or by telephone at (202) 366-2992. Sincerely, Paul Jackson Rice Chief Counsel Enclosure"; |
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ID: aiam0448OpenMr. Joseph M. Mazzafro, Manager, Production Engineering, Strick Corporation, U. S. Highway No. 1, Fairless Hills, PA, 19030; Mr. Joseph M. Mazzafro Manager Production Engineering Strick Corporation U. S. Highway No. 1 Fairless Hills PA 19030; Dear Mr. Mazzafro: This is in reply to your letter of September 21, 1971, to Mr. Dougla Toms, Administrator, National Highway Traffic Safety Administration, requesting an interpretation on the mounting of identification lamps on your trailers.; We hesitate to agree with you that it is not practicable to mount th identification lamps at the extreme height of the trailer. It would appear to be practicable to mount these lamps at the extreme height, even if a shield were necessary to prevent damage to the lamps during use.; If the identification lamps are mounted at the extreme height of th trailer, the clearance lamp mounting height is optional, therefore, clearance lamps could be mounted on the rear crossmember, as shown on your drawing SK-24139.; Sincerely, E. T. Driver, Director, Office of Operating Systems, Moto Vehicle Programs; |
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ID: aiam2475OpenMr. R. E. Weil, Exterior Lighting Development, Chrysler Corporation, P.O. Box 1118, Detroit, MI, 48231; Mr. R. E. Weil Exterior Lighting Development Chrysler Corporation P.O. Box 1118 Detroit MI 48231; Dear Mr. Weil: This is in reply to your letter of September 16, 1976, to Mr. Brooks o this agency on photometric test requirements of multiple compartment and multiple lamp configurations. You have asked for our concurrence on two interpretations of Standard No. 108, as discussed below.; In your 'example 1', on vehicles designed with a two lamp system parking and (or taillamp) and turn signal functions are combined in each lamp of the two lamp system. You have asked whether the second lamp in this system would be treated as supplemental and need not meet the photometric requirements for required lamps.; The answer is no. As you are aware the photometric requirements o multiple lamps or multiple compartment lamps, where a tail or parking lamp is combined with the turn signal lamp, are partially determined by Note 4 to SAE Standard J588e *Turn Signal Lamps*. Note 4 establishes permissible ratios of intensity between functions *i*. *e*. that the intensity of the tail or parking lamps shall not be so great as to diminish the effectiveness of the turn signal function. Where two lamps are used and the distance between filament centers does not exceed 22 inches (as appears to be the case here) the combination of the lamps must be used to meet the photometric requirements for the corresponding number of lighted sections. (Paragraphs 3.1 of J585d, J588e). Further, the ratio of the turn signal to the tail or parking lamps must be computed with all the lamps lighted (Note 4). With reference to those vehicles designed with a two-lamp system (your example 1), your first answer is the correct one, the lamps would be photometered together to meet the two compartment requirements for the two lamp functions performed, as specified in Table 1 of Standard No. 108.; With respect to your example 2, a multiple compartment lamp with on compartment performing turn signal and parking or tail lamp functions, and the other portion the function of parking or tail lamp only, photometric requirements for the tail lamp function are determined on the basis of the output of the two compartments. The single compartment parking lamp may, however, be treated as a 'supplemental' lamp, except that the candlepower ratios (with turn signal lamp) must be met with both parking lamp compartments illuminated.; Sincerely, Frank A. Berndt, Acting Chief Counsel |
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ID: aiam0366OpenMrs. Annemarie Shelness, Physicians for Automotive Safety, 50 Union Avenue, Irvington, NJ 07111; Mrs. Annemarie Shelness Physicians for Automotive Safety 50 Union Avenue Irvington NJ 07111; Dear Mrs. Shelness: Thank you for your letter of May 24, 1971, informing us of Mr. Hurley' Safe-Trip-Seat and inquiring about enforcement of Standard No. 209 concerning a non-complying Hankscraft child harness.; Mr. Hurley sent us a letter on April 10, 1971, informing us of hi device. Our letter to him was sent out on May 10, 1971, so he had not received it when he wrote to you. I believe we have adequately informed him of his lack of compliance with Standard No. 213 and the penalties involved if he does not. A copy of our letter to him is enclosed for your information. Our compliance personnel were also alerted on the Safe-Trip-Seat.; Hankscraft was notified in a letter dated March 23, 1971, of ou position on any child harness (copy enclosed). Please note that we will enforce Standard No. 209 on harnesses advertised in any way to provide any measure of protection in a vehicle accident. We will not enforce the requirements of Standard No. 209 of harnesses which carefully state that they are not intended to protect a child from the effects of an accident.'; A copy of this letter is being forwarded to our compliance personne for appropriate action by them.; Sincerely, Clue D. Ferguson, Director, Office of Crashworthiness, Moto Vehicle Programs; |
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ID: aiam5164OpenMr. Brett J. Higgins 10257 Slater Ave. #103 Fountain Valley, CA 92708; Mr. Brett J. Higgins 10257 Slater Ave. #103 Fountain Valley CA 92708; "Dear Mr. Higgins: This responds to your letter of March 25, 1993 t former Chief Counsel Paul Jackson Rice seeking information on how the laws and regulations administered by this agency would apply to an item of equipment you wish to sell. According to your letter, the item is a special clamp that is applied to the shoulder strap of a seatbelt as an after-market item. The purpose of this clamp is to allow for slack in the shoulder harness section of a seatbelt thus allowing it to be worn more comfortably. I am pleased to have this opportunity to explain our laws and regulations to you. The National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1381 et seq., the Safety Act) authorizes this agency to issue motor vehicle safety standards for new motor vehicles and new items of motor vehicle equipment. We have exercised this authority to establish Standard No. 208, Occupant Crash Protection (49 CFR 571.208). This standard requires new motor vehicles to be equipped with safety belts and requires that those belts meet specified fit and comfort requirements, as set forth in S7 of the standard. However, Standard No. 208 does not apply to aftermarket items that seek to alter belt fit and/or comfort. Hence, you are not required to certify that this device complies with Standard No. 208 before offering the device for sale. In addition, you are not required to get some sort of 'approval' from this agency before offering this device for sale. NHTSA has no authority to 'approve' motor vehicles or motor vehicle equipment, nor do we endorse any commercial products. Instead, the Safety Act establishes a 'self- certification' process under which each manufacturer is responsible for certifying that its products meet all applicable safety standards. As stated above, this device is not subject to any safety standard, so you do not have to make any certification. Although none of our safety standards directly apply to this device, there are several provisions in the Safety Act that are relevant. Manufacturers of motor vehicle equipment such as your belt positioning device are subject to the requirements in sections 151-159 of the Safety Act (15 U.S.C. 1411-1419) concerning the recall and remedy of products with defects related to motor vehicle safety. In addition, use of your product could be affected by section 108(a)(2)(A) of the Safety Act (15 U.S.C. 1397(a)(2)(A)). That section prohibits manufacturer, distributors, dealers, and repair shops from knowingly 'rendering inoperative,' in whole or in part, any device or element of design installed on or in a vehicle in compliance with an applicable safety standard. There are two elements of design in a vehicle that might be 'rendered inoperative' by the use of your belt positioning device. One is the occupant protection afforded by belts that meet the specified fit and comfort requirements. The other element of design that could be rendered inoperative by the use of your device is the burn resistance required by Standard No. 302, Flammability of Interior Materials (49 CFR 571.302). The materials used in the interior of vehicles, including the seat belts, seat backs and cushions, trim panels, and headliner must comply with the burn resistance requirements of Standard No. 302 to reduce deaths and injuries in the event of a fire in the vehicle's interior. If your device renders inoperative the belt fit and comfort requirements specified in Standard No. 208 or does not comply with burn resistance requirements, it could not be installed in a vehicle by any manufacturer, distributor, dealer, or repair shop. I note that NHTSA has received a number of inquiries about devices similar to the one you plan to sell. As we have advised others, this agency is concerned that a belted occupant could inadvertently use such products to introduce excessive slack in the upper torso belt and thereby reduce the effectiveness of that belt. We encourage you to provide instructions with the product that warn users not to introduce excessive slack and provide detailed guidance for users on what is an excessive amount of slack. I have enclosed a general information sheet for new manufacturers that gives a thumbnail sketch of NHTSA's regulations and provides information on how to obtain copies of those regulations. 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 Enclosure"; |
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ID: aiam0736OpenMr. Thomas S. Pieratt, Jr., Executive Secretary, Truck Equipment and Body Distributors Assn., 602 Main Street, Cincinnati, OH 45202; Mr. Thomas S. Pieratt Jr. Executive Secretary Truck Equipment and Body Distributors Assn. 602 Main Street Cincinnati OH 45202; Dear Mr. Pieratt: This is in reply to your letter of June 9 asking whether pole trailer must be certified.; The answer is no. According to 49 CFR S 567.2(a), only motor vehicle to which one or more Federal motor vehicle safety standards are applicable must be certified. The only Federal standard currently in effect that applies to 'trailers', Standard No. 108, specifically exempts 'pole trailers' from its applicability and therefore pole trailers need not be certified.; Your letter of February 23 regarding clearance lamps and identificatio lamps is still under consideration and we hope to provide a response in the near future.; Yours truly, Richard B. Dyson, Assistant 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.