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 |
|---|---|
| search results table | |
ID: aiam3277OpenHonorable Samuel S. Stratton, House of Representatives, Washington, D.C. 20515; Honorable Samuel S. Stratton House of Representatives Washington D.C. 20515; Dear Mr. Stratton: This responds to your recent correspondence requesting information o behalf of the Schenectady County Traffic Safety Board. The Safety Board is concerned that many new or converted propane-powered vehicles carry no identification indicating that the vehicles contain propane fuel instead of gasoline. The Safety Board states that this creates a dangerous situation for firemen, policemen or other emergency personnel who respond to accidents involving propane-powered vehicles. You were asked to initiate legislative action to require such identification on these vehicles.; The National Highway Traffic Safety Administration issues safet standards and regulations governing the manufacture of new motor vehicles and motor vehicle equipment. Therefore, if there were a demonstrated safety need for identification on propane vehicles, the agency would have authority under the National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1381, *et seq*.) to require a label or tag as was suggested by the Safety Board. Please inform the Safety Board that it should petition the agency to initiate rulemaking action to establish such a requirement if it has information or evidence indicating that a safety problem does indeed exist. I have enclosed a copy of the regulation which explains what must be included in a Petition for Rulemaking.; The agency has no authority under the Vehicle Safety Act to regulat used motor vehicles and, therefore, could not require an identification label on a used vehicle that is converted to propane fuel. Congress left this jurisdiction to the individual States. Consequently, Congressional action or action at the State level would be required to mandate identification labels on used vehicles.; I am also enclosing a copy of a letter of interpretation the agenc issued last August which discusses the implications under Federal law of installing auxiliary fuel tanks in motor vehicles and of converting vehicles to the use of propane gas. Although not directly related to the Safety Board's concern, it might be of interest.; I hope this has been responsive to your inquiry. If you have an further questions, please contact Hugh Oates of my staff at 2020-426-2992.; Sincerely, Frank Berndt, Chief Counsel |
|
ID: aiam4418OpenMr. Gary W. Rossow, Director, Government Technical Affairs, Mercedes-Benz Truck Company, Inc., 4747 N. Channel, P.O. Box 3849, Portland, OR 97208; Mr. Gary W. Rossow Director Government Technical Affairs Mercedes-Benz Truck Company Inc. 4747 N. Channel P.O. Box 3849 Portland OR 97208; Dear Mr. Rossow: This responds to your request for an interpretation of Federal Moto Vehicle Safety Standard No. 121, *Air Brake Systems*. Section S6.2.1 of that standard specifies for certain tests conducted on a dynamometer that '(t)he dynamometer inertia for each wheel is equivalent to the load on the wheel with the axle loaded to its gross axle weight rating.' According to your letter, you have interpreted the term 'equivalent' in this section to 'authorize compliance testing by reference to axle loads under actual stopping conditions.' You requested confirmation of this interpretation. As discussed below, we disagree with your suggested interpretation.; By way of background information, the National Highway Traffic Safet Administration (NHTSA) does not provide approvals of motor vehicles or motor vehicle equipment. Under the National Traffic and Motor Vehicle Safety Act, it is the responsibility of the manufacturer to ensure that its vehicles or equipment comply with all applicable standards. The following represents our opinion based on the facts provided in your letter.; As indicated in your letter, your request for an interpretation wa submitted in light of recent correspondence between your company and NHTSA's Office of Vehicle Safety Compliance (OVSC). OVSC requested you to submit information on the compliance with Standard No. 121 of the Mercedes-Benz model L-1317, a two axle straight truck. You responded to that request by submitting a compliance certification and interpretation concerning section S6.2.1. In letter dated April 9, 1987, OVSC informed you that it did not agree with your interpretation.; Standard No. 121's dynamometer tests are set forth in section S5.4 That section specifies that brake assemblies must meet the requirements of S5.4.1 (brake retardation force--relevant only to towed vehicles), S5.4.2 (brake power), and S5.4.3 (brake recovery), under the conditions of S6.2. One of those conditions, set forth in S6.2.1, is as follows:; >>>S6.2.1 The dynamometer inertia for each wheel is equivalent to th load on the wheel with the axle loaded to its gross axle weight rating. For a vehicle having additional gross axle weight ratings specified for operation at reduced speeds, the GAWR used is that specified for a speed of 50 mph, or, at the option of the manufacturer, any speed greater than 50 mph.<<<; In support of your suggested interpretation, you noted that axle load of a decelerating vehicle vary under different deceleration conditions, i.e., as a vehicle travelling forward decelerates, the load on the axles shifts so that the front axle load rises and rear axle load falls. You stated that it is your reading of Standard No. 121 that the manufacturer 'can assess compliance by either using a static load value or determining which of the varying values of the axle load should be considered in view of actual vehicle behavior.' With respect to gross axle weight rating (GAWR), you suggested that when used in the context of Parts 567 and 568, the GAWR is properly measured in a static manner, to permit determination of whether the load carrying capacity of a vehicle axle in actual use has been reached. For dynamometer tests of service brakes under dynamic conditions, however, you argued that such tests should properly take into account the dynamic effects of deceleration.; You then stated the following: >>>The language of S6.2.1, setting dynamic test conditions, indicate that the dynamometer inertia for each wheel is to be set at the 'equivalent' to the load on the wheel, when the axle is loaded to its GAWR (i.e., its load-carrying capacity). This language is not restrictive and grants a manufacturer the flexibility of determining an 'equivalent' loading in consideration of the dynamic phenomena in conducting the tests required by S5.4. Thus, the static GAWR is permitted to be linked to dynamic conditions by the word 'equivalent.'<<<; We disagree with your suggested interpretation, which we believe i inconsistent with the language of S6.2.1, past interpretations of that provision, and the compliance test procedures the agency has long followed with respect to this provision. As indicated above, S6.2.1 specifies that the dynamometer inertia for each wheel is 'equivalent to the load on the wheel with the axle loaded to its gross axle weight rating.' The phrase 'equivalent to the load' uses the singular 'load,' instead of the plural 'loads,' to show that the dynamometer inertia has only a single value. By itself, this suggests that S6.2.1 was not intended to provide multiple options for the dynamometer inertia setting, depending on the dynamic conditions simulated.; Further, the overall language of S6.2.1 shows how the singl dynamometer inertia setting is to be determined. The term 'GAWR' is defined in 49 CFR Part 571.3 as 'the value specified by the vehicle manufacturer as the load-carrying capacity of a single axle system, as measured at the tire-ground interfaces.' When an axle is loaded to its load-carrying capacity, there is one 'load on the wheel,' at whose 'equivalent' the dynamometer inertia must be set.; While we believe that the language of section S6.2.1 is clear on th issue raised by your letter, we also note that agency guidance in the form of past interpretation letter and OVSC's laboratory procedures for Standard No. 121 are also clear. In an interpretation letter to Wagner Electric, dated May 26, 1972, the agency stated:; >>>In the dynamometer test conditions of S6.2.1, the dynamomete inertia for each brake assembly is based on 1/2 the GAWR of the axle. The rating for each axle is required to be stated separately. If, in the example you give, you choose to give 17,000 pounds as the rating for each axle, then the dynamometer inertia would be at 8,500 pounds for each brake assembly.; <<>>Section S5.1.1 does not specify whether or not the vehicle is movin as a test condition for the requirement. In view of the absence of this test condition, the NHTSA will resolve differences in this test condition in the manufacturer's favor if they affect the outcome of testing.<<<; We do not agree that this letter supports your suggeste interpretation. The letter addressed only the issue of how a requirement should be read in view of the absence of a particular test condition. As explained at length above, we conclude that section S6.2.1 clearly specifies the particular test conditions to be followed for this section. Therefore, the Oshkosh letter is not relevant to requests for interpretation of S6.2.1.; You also argued that in order to provide an appropriate braking system with proper distribution of brake forces between the axles, its design must take into account the transfer of weight from the rear axle to the front axle during normal and emergency braking conditions. You stated that such a design and compliance test leads to a significant reduction in premature lockup of the rear axle. You also argued that NHTSA has recognized your braking system as 'a safe and effective system' in its research testing.; We agree that a manufacturer must take into account the transfer o weight from the rear axle to the front axle when designing an appropriate braking system. This is necessary to provide safe brake performance during varying loading conditions, for normal and emergency brake applications on varying road conditions, and it is so for all kinds of vehicles. However, the requirements of Standard No. 121 do not require vehicles to have too much rear braking, as you appear to imply. The requirements of S5.4.2 (Brake Power), and S5.4.3 (Brake Recovery), are minimum performance requirements intended to help ensure that brakes retain adequate stopping capacity during and after exposure to conditions caused by prolonged or severe use, such as long, downhill driving. In practice, in order to perform well in such conditions, both front and rear brakes must have a minimum capacity, and this capacity is related to GAWR despite the fact that the actual loads borne by the front and rear axles vary during different brake applications. The agency therefore referred to GAWR in section S6.2.1, because this is an objective value that is readily ascertainable for every vehicle, and performance based on this value meets the particular safety need provided for by the requirements of section S5.4. These minimum requirements are not intended, nor do they operate, as a restriction on the design decisions that manufacturers must make independently to distribute braking capacity to meet anticipated load distributions.; Contrary to your assertion, NHTSA has not concluded that your brak system is 'safe and effective.' We also note that the quotations of the agency's research report cited in your letter address only limited aspects of braking performance and are taken out of context. We note that you stated that '(t)he Agency reported finding that the subject vehicle's front and rear axles were '. . .well balanced and tended to lock at close to the same pedal effort level.' (p. 19).' A more complete quotation is as follows:; >>>. . . In the empty driver best effort stops the driver was also abl to utilize this peak friction, although not as effectively as the antilock, because the brakes on front and rear axles of the vehicle were well balanced and tended to lock at close to the same pedal effort level. In the loaded case, however, the front axle tended to lock prematurely and it was not possible for the driver to maintain all four wheels near the peak friction level. He could keep the front tires near the peak but when this occurred rear braking was relatively low. If he applied more braking, the front axle locked and he lost steering control due to lack of lateral traction at the front tires.'<<<; Based on the information before the agency, OVSC is continuing it investigation concerning the compliance of your vehicles with Standard No. 121.; Sincerely, Erika Z. Jones, Chief Counsel |
|
ID: aiam0908OpenMr. Stan Haransky, Associate Director, Truck Body & Equipment Association, Inc., 5530 Wisconsin Avenue, Suite 1220, Washington, DC 20015; Mr. Stan Haransky Associate Director Truck Body & Equipment Association Inc. 5530 Wisconsin Avenue Suite 1220 Washington DC 20015; Dear Mr. Haransky: Thank you for your letter of November 15, 1972, and your kind word about my participation in your convention.; In your letter you asked a question that arose at the convention concerning the responsibility of a tank manufacturer who completes a tank truck for a customer who carries both gasoline an fuel oil. You asked,; >>>'Can a tank manufacturer by simply certifying the GVWR make a uni which will be legal at full load with gasoline, the lighter of the two products, and leave it to the user to ensure that he does not exceed the GVWR when he is carrying a mixed load or fuel oil only?'<<<; On the specific and limited facts that you have given, the answer i that the manufacturer will not be in violation of the Certification regulations. There are two ways in which a manufacturer might find himself liable on slightly different facts, however. If in an way the manufacturer provides information to the purchaser, through owner's manuals, promotional materials, or otherwise, which could reasonably be considered a 'rated cargo load', he will be in violation of S567.5(a)(5) if the GVWR does not reflect that figure. For example, if the vehicle were described explicitly as being capable of carrying 5,000 gallons of fuel oil, we would consider that to be the equivalent of a rating of that volume times the normal density of the oil.; The other possible liability would be for a safety-related defect. Thi would arise in a case where the vehicle was found to be unsafely equipped for carrying the loads that the manufacturer has reason to know would be imposed on it. Such a finding would depend on all the facts of an individual case. Obviously, the best course for the manufacturer, from the standpoint of both safety and the avoidance of liability, is to equip his vehicles fully with equipment that is rated to carry the loads that he believes the vehicles will carry.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
|
ID: aiam2935OpenMr. James R. Randolph, 765 Malley Drive, Northglenn, CO 80233; Mr. James R. Randolph 765 Malley Drive Northglenn CO 80233; Dear Mr. Randolph: This responds to your December 28, 1978, letter concerning an auxiliar fuel tank installed by the dealer on a 1978 Ford van that you purchased. You are concerned that the auxiliary tank represents a safety hazard due to the location of the tank's filler cap in the left rear wheel-well.; Federal Motor Vehicle Safety Standard No. 301-75, *Fuel Syste Integrity*, specifies performance requirements for fuel systems on motor vehicles. Although the standard applies to completed vehicles rather than to fuel tanks or other fuel system components, your dealer had to assure that your van complied with the standard. A person who mounts an auxiliary fuel tank on a new motor vehicle before the vehicle's first purchase in good faith for purposes other than resale is a vehicle alterer under National Highway Traffic Safety Administration regulations. That person is required by 49 CFR 567.7 to affix a label to the vehicle stating that, as altered, the vehicle conforms to all applicable Federal motor vehicle safety standards--including Safety Standard No. 301-75. Therefore, there should be an 'alterer' label on your van in addition to the certification label placed on the vehicle by the original manufacturer.; Even if the vehicle complies with Safety Standard No. 301-75, th location and design of the auxiliary fuel tank could constitute a safety-related defect for which the manufacturer would also be responsible. I am, therefore, forwarding a copy of your letter to the agency's Office of Defects Investigation. That office will examine this situation and may be in touch with you at a later date.; Thank you for your letter and for bringing this matter to ou attention.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
|
ID: aiam3627OpenMr. F. Michael Petler, Head, Administration, Government Relations Department, Suzuki Motor Co., Ltd., P.O. Box 1100, Brea, CA 92621; Mr. F. Michael Petler Head Administration Government Relations Department Suzuki Motor Co. Ltd. P.O. Box 1100 Brea CA 92621; Dear Mr. Petler: This responds to your October 27, 1982, letter asking for permission t place the certification labels for certain motorcycles produced by Suzuki Motor Co. in locations not previously permitted by Part 567, *Certification*.; You request alternative locations, because some motorcycles ar equipped with fairings as standard equipment. These fairings would obscure the certification labels if the labels were to be installed in their required location. You propose, as an alternative, the installation of the labels on the down tubes in front of the engine on either the right or left side. In consideration of the problems of installing the certification labels in their normal positions on vehicles equipped with fairings and since the agency desires that these labels be easily readable, we grant your request to install your labels in these limited instances in the alternative locations that you suggested.; Sincerely, Frank Berndt, Chief Counsel |
|
ID: aiam3332OpenMr. Olin F. Wenrick, Trophy, Rt. 1, Box 19875, Hwy. M 205, Edwardsburg, Michigan 49112; Mr. Olin F. Wenrick Trophy Rt. 1 Box 19875 Hwy. M 205 Edwardsburg Michigan 49112; Dear Mr. Wenrick: This will confirm your telephone conversation with Mr. Schwartz of m office concerning the compliance of your vehicle identification numbering system with the requirements of Federal Motor Vehicle Safety Standard No. 115, *Vehicle Identification Number*.; The National Highway Traffic Safety Administration does not giv advance approval of a manufacturer's compliance with motor vehicle safety standards or regulations, as it is the manufacturer's responsibility under the National Traffic and Motor Vehicle Safety Act to ensure that its vehicles comply with the applicable safety standards. However, my office has reviewed your proposed system. Based on our understanding of the information which you have provided, your system will apparently comply with Standard No. 115 upon receipt of the chart you are sending identifying the coding used to designate the length of your vehicles.; Sincerely, Frank Berndt, Chief Counsel |
|
ID: aiam2870OpenMr. Brian Gill, Manager, Certification Department, American Honda Motor Co., Inc., P.O. Box 50, Gardena, California 90247; Mr. Brian Gill Manager Certification Department American Honda Motor Co. Inc. P.O. Box 50 Gardena California 90247; Dear Mr. Gill: This is in reply to your letter of August 24, 1978, asking for a interpretation of Motor Vehicle Safety Standard No. 123, *Motorcycle Controls and Displays*. Specifically, you have asked whether Honda's proposed manual fuel shutoff control design would comply with the standard. In this proposed design, in your word 'a second 'Off' position will be provided 180 degrees from the required position.'; Standard No. 123 requires the manual fuel shutoff control to b 'operable as specified in Column 3 [of Table 1]' (S5.2.1). Table 1 specifies that the 'Off' position is with the 'control forward.' Although the control in your proposed design shuts the fuel valve when pointed forward, it also shuts the valve at a position 180 degrees from the complying one, with the 'control backward,' so to speak. Thus, the control is not 'operable as specified' within the meaning of the requirement.; As you know, the safety purpose of standardization of control locatio and operation is to insure that the novice cyclist, and those who change cycles frequently, are not confused when controls must be operated under emergency conditions. Since your proposed control design is operable both forward and backward it does not comply with Standard No. 123.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
|
ID: aiam3762OpenMs. Susan Reilly, Reilly Manufacturing, P.O. Box 51, Mt. Vernon, IA 52314; Ms. Susan Reilly Reilly Manufacturing P.O. Box 51 Mt. Vernon IA 52314; Dear Ms. Reilly: This responds to your letter asking whether a motorcycle helme fastener your company produces, called 'Alpha Clip,' complies with Federal requirements.; By way of background information, this agency does not give approval of vehicles or equipment. The National Traffic and Motor Vehicle Safety Act places the responsibility on the manufacturer to ensure that its vehicles or equipment comply with applicable standards.; Safety Standard No. 218, *Motorcycle Helmets*, includes various minimu performance requirements for motorcycle helmets. The only requirement directly relevant to your fastener is the retention test, which is set forth at section S5.3. The letter you enclosed from the University of Southern California suggests that the clip passes that test.; I would note that Standard No. 218 only applies to new motorcycl helmets and not to replacement equipment for motorcycle helmets. Thus, unless your clip was sold as part of a new motorcycle helmet, the requirements of Standard No. 218 would not be directly applicable. (Please note, however, that the agency discourages helmet users from modifying their helmets. Section S5.6.1 of the standard requires that the following instruction be placed on helmets: 'Make no modifications....'); I would also note that should a safety- related defect be discovered i your device, whether by the agency or by yourself, you as the manufacturer would be required under sections 151 *et seq*. of the Act to notify owners, purchasers, and dealers and provide a remedy for the defect. These provisions apply regardless of whether the device is covered by a safety standard. A copy of the Act is enclosed.; Sincerely, Frank Berndt, Chief Counsel |
|
ID: aiam3298OpenMr. Emerson D. Gilbert, Engineer, Yellowstone, Inc., 28163 C.R. 20 West, P.O. Box 1128, Elkhart, Indiana 46515; Mr. Emerson D. Gilbert Engineer Yellowstone Inc. 28163 C.R. 20 West P.O. Box 1128 Elkhart Indiana 46515; Dear Mr. Singleton(sic): This will confirm your telephone conversation of April 23, 1980, wit Mr. Nelson Erickson of the Office of Vehicle Safety Standard concerning Federal Motor Vehicle Safety Standard No. 115 - Vehicle identification number.; The National Highway Traffic Safety Administration (NHTSA) does no give advance approval of a manufacturer's compliance with motor vehicle safety standard or regulations, as it is the manufacturer's responsibility under the National Traffic and Motor Vehicle Safety Act to ensure that its vehicles comply with the applicable safety standards. However, my office has reviewed your proposed system. Based on our understanding of the information which you have provided, your system apparently complies with Standard No. 115.; Sincerely, Frank Berndt, Chief Counsel |
|
ID: aiam2523OpenMr. 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 8, 1977, letter asking whether a Ne York state requirement mandating the installation of both side emergency doors and rear emergency doors in school buses would mean that both emergency doors would be required to comply with the school bus exit specifications in Standard No. 217, *Bus Window Retention and Release*.; The NHTSA has determined previously that only those exits required b S5.2.3 must meet the requirement specified for school bus emergency exits in Standard No. 217. Paragraph S5.2.3 requires either a rear emergency door or a side emergency door and a rear push out window. The side emergency door to which you refer is installed in addition to a rear emergency door. The presence of the rear emergency door, alone, satisfies the requirements of S5.2.3. Therefore, a side emergency door is not required by the standard and need not meet the specifications for school bus emergency exits. Emergency exits installed in school buses beyond those required in S5.2.3 must comply with regulations applicable to emergency exits in buses other than school buses. These requirements are also detailed in Standard No. 217.; Sincerely, Frank A. Berndt, Acting 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.