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: aiam4670OpenMr. W. Marshall Rickert Motor Vehicle Administrator Maryland Department of Transportation 6601 Ritchie Highway Glen Burnie, MD 21062; Mr. W. Marshall Rickert Motor Vehicle Administrator Maryland Department of Transportation 6601 Ritchie Highway Glen Burnie MD 21062; "Dear Mr. Rickert: Thank you for your letter seeking this agency' opinion as to whether the State of Maryland may amend its motor vehicle regulations to permit the installation of aftermarket tinting on motor vehicle windows, for individuals who may desire this for medical reasons. I am pleased to have this opportunity to describe the legal principles that relate to your question. The National Highway Traffic Safety Administration ('NHTSA') is responsible for issuing Federal motor vehicle safety standards that impose requirements for specific levels of safety performance for new motor vehicles and motor vehicle equipment. Federal Motor Vehicle Safety Standard No. 205, Glazing Materials (49 CFR 571.205), which has been in effect since 1968, imposes a minimum level of light transmittance of 70 percent in all areas requisite for driving visibility (which includes all windows on passenger cars). The purpose of this requirement is to ensure adequate visibility through the windows, thereby reducing the risk of a motor vehicle crash. Although Federal motor vehicle safety standards apply directly only to new vehicles and equipment, Federal law also imposes limits on the addition of tinting materials to motor vehicle glazing after vehicles have been purchased by consumers. Pursuant to section 108(a)(2) of the National Traffic and Motor Vehicle Safety Act, 15 U.S.C. 1397(a)(2), manufacturers, distributors, dealers, or motor vehicle repair businesses may not 'render inoperative' any equipment or element of design installed in compliance with a Federal safety standard. Thus, those businesses may not install tinting that reduces the light transmittance of windows covered by Standard 205 to a level below the Federal requirement of 70 percent, since that would make the windows 'inoperative' within the meaning of Standard 205. This Federal prohibition is similar to that imposed by section 22-104 of the Maryland Vehicle Law, which provides: A person may not willfully or intentionally remove or alter any safety device or equipment that has been placed on any motor vehicle . . . in compliance with any law, rule, regulation, or requirement of . . . the United States or of this State . . . unless the removal or alteration is permitted by rule or regulation adopted by the Maryland Motor Vehicle Administrator. The 'render inoperative' provision of Federal law does not apply to actions by individual vehicle owners. Therefore, each State may regulate the extent to which aftermarket tinting may be applied by vehicle owners to their own vehicles. Thus, although section 22-104 appears to preclude aftermarket tinting by any person if the result would be to reduce the level of light transmittance below 70 percent, Maryland may amend its rules or regulations to permit such tinting by individuals, for medical or any other reasons deemed valid by the State. However, Maryland has no authority to grant any exemptions, including medical exemptions, from the 'render inoperative' prohibition of Federal law that applies to commercial entities. Hence, regardless of any provisions of Maryland law, no manufacturer, distributor, dealer, or motor vehicle repair business may legally install window tinting film on a vehicle, unless the vehicle continues to comply with the Federal light transmittance requirements. In adopting Standard 205, NHTSA determined that a minimum light transmittance of 70 percent is necessary to meet the need for motor vehicle safety. This is the same level of light transmittance contained in the Safety Code of the American National Standards Institute. If, as your letter suggests, Maryland is considering permitting vehicle owners to modify their vehicles such that their windows will have a lower level of light transmittance, we would urge you to carefully consider the safety consequences of such an exemption. Please let me know if you need any further information on this subject. Sincerely, Paul Jackson Rice Chief Counsel"; |
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ID: aiam1188OpenMr. Dennis C. Sullivan, Pacific Gas and Electric Company, 77 Beale Street, San Francisco, CA 94106; Mr. Dennis C. Sullivan Pacific Gas and Electric Company 77 Beale Street San Francisco CA 94106; Dear Mr. Sullivan: This is in reply to your letter of June 21, 1973, inquiring as to you responsibilities regarding the conformity and certification of motor vehicles on which Pacific Gas and Electric Company (PG & E) performs certain manufacturing operations. You indicate that the operations involve 'body transfers,' in which used bodies are first removed from used trucks chassis, repaired and repainted, and then transferred to new cabs and chassis. The two questions you raise are:; >>>1) Must the vehicle comply with Federal motor vehicle safet standards at the time of the body transfer, and; 2) If not, need it comply at the time of sale to the public.<<< You indicate that your position is that you believe the answer to bot questions to be negative, that with respect to the first question, the vehicle need not conform nor be certified as conforming because no 'sale' of the vehicle has occurred, and with respect to the second question, you argue that the provisions of the National Traffic and Motor Vehicle Safety Act regarding used vehicles (Sec. 108(b)(1), 15 U.S.C. S 1397 (b)(1) appear to exempt these vehicles from conforming to the standards when they are sold.; We must disagree with both of your conclusions. We agree that th operations performed by PG & E, adding used bodies to new chassis, make PG & E a 'final-stage manufacturer' as defined in the Certification and Vehicles Manufactured in Two or More Stages regulations (49 CFR Parts 567, 568). The Certification regulations require that final-stage manufacturers who complete vehicles for their own use ascertain and certify conformity to all applicable standards as of the time the final-stage manufacturing operations are performed. We do not agree that section 108(b)(1) of the Safety Act (15 U.S.C. S 1397(a)(1)) applies only in connection with the sale of vehicles. That section also requires conformity with respect to the introduction and delivery for introduction of vehicles in interstate commerce. We have construed this language to include the use of any vehicle by its manufacturer on the public highways, even if the vehicle has not been sold. The responsibility for certification under the regulations is concomitant with the responsibility for conformity, and, similarly, is not dependent upon a vehicle sale.; The National Traffic and Motor Vehicle Safety Act, in our view, als requires a vehicle used by its manufacturer to conform to all applicable standards at the time of its eventual sale by that manufacturer. Our conclusion is based upon section 108(b)(1), which requires conformity until the first purchase of the vehicle for a purpose other than resale. where a manufacturer uses his own vehicles, that purchase would not take place until the manufacturer ultimately sells the vehicle. However, the NHTSA is aware that conformity of vehicle systems which deteriorate under normal use may be impossible to maintain, and as a matter of administrative practice does not consider it necessary for such a manufacturer to renew conformity when his use of the vehicle has been bona fide.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam1472OpenMr. Douglas A. Hughes, Director of Transportation, Heavy & Specialized Carriers Conference of American Trucking Associations, 1155 Sixteenth Street, N.W., Suite 711, Washington, DC 20036; Mr. Douglas A. Hughes Director of Transportation Heavy & Specialized Carriers Conference of American Trucking Associations 1155 Sixteenth Street N.W. Suite 711 Washington DC 20036; Dear Mr. Hughes: This responds to your April 23, 1974, request for an explanation of th meaning and use of the term 'Gross axle weight rating' (GAWR) in Federal motor vehicle safety standards.; The concept of GAWR and 'Gross vehicle weight rating (GVWR) ar interrelated, and the two terms are defined as follows:; >>>'Gross axle weight rating' or 'GAWR' means the value specified b the manufacturer as the load-carrying capacity of a single axle system, as measured at the tire-ground interfaces.; 'Gross vehicle weight rating' or 'GVWR' means the value specified b the manufacturer as the loaded weight of a single vehicle.<<<; In both cases it is the manufacturer who specifies the values, and h is free to specify whatever values he himself decides are correct. Both the NHTSA in its compliance tests, and the Bureau of Motor Carrier Safety on the road, will judge the vehicle on the basis of the values assigned. Therefore it is in the interest of the manufacturer to assign values which accurately reflect the load-bearing ability of the vehicle and its suspension.; The sum of the GAWR's must at least equal the specified GVWR to avoi overloading the axle systems, and the GAWR sum may, of course, exceed the GVWR. Typically the manufacturer balances the commercial advantage of specifying a higher GVWR against the expense of higher GAWR's.; The GAWR is measured at the tire-ground interfaces which means that th tires, wheels, brakes and suspension components are included in the determination. Typically an axle assembly is rated by its manufacturer, who takes into account the braking ability of the axle to stop the load. Although this factor should always have been taken into consideration, the advent of Standard 121 may cause axle and brake manufacturers to reassess the values they have assigned to brake systems in the past.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam4220OpenMr. Tsuyoshi Shimizu, Vice-President, MMC Services, Inc., 3000 Town Center - Suite 1960, Southfield, MI 48075; Mr. Tsuyoshi Shimizu Vice-President MMC Services Inc. 3000 Town Center - Suite 1960 Southfield MI 48075; Dear Mr. Shimizu: Thank you for your letter requesting an interpretation of Standard No 201, *Occupant Protection in Interior Impact*. You asked how the instrument panel impact protection requirements of S3 of the standard would apply to an occupant compartment interior described in your letter. In particular, you asked whether the 'center console' described in your letter would be considered a console assembly that is exempt from the requirements of S3.1 of the standard. I hope the following discussion answers your questions.; S3.1 of the standard sets forth the head impact protection requirement for the instrument panel. S3.1.1, in turn, sets out several exemptions to the instrument panel performance requirements. S3.1.1(a), which provides that the performance requirements do not apply to 'console assemblies,' is the first exemption which is relevant to your design. As depicted in your letter, there is a short structure, which you referred to as the center console, that is mounted on the floor of the vehicle and is located primarily between the vehicle seats. The gear shift lever is mounted in this structure. Although the structure is connected to the bottom of the instrument panel, you pointed out that there is a 'gap,' which appears to be an indentation, between 'the instrument panel and the center console which makes the console and instrument panel area distinct and separate areas.'; The purpose of the head impact requirement is to ensure that portion of a vehicle's instrument panel which are mounted forward of the front seat and are likely to be struck by an occupant's head in a frontal impact provide adequate protection. Thus, the head impact protection requirements apply primarily to the upper portions of the instrument panel. As stated in an interpretation letter of January 12, 1983, to the Blue Bird Body Company, the agency considers the instrument panel to be the vehicle structure below the windshield used to mount a vehicle's gauges. Since the 'center console' described in your letter is a low-lying structure mounted on the floor and lies primarily between the vehicle seats, the agency would consider it to be a console assembly rather than a part of the instrument panel.; The second exemption which is relevant to your design is S3.1.1(e) o the standard. That section exempts areas of the instrument panel that are 'below any point at which a vertical line is tangent to the rearmost surface of the panel.' The area labeled section B in your diagram is such an area and thus does not have to meet the performance requirements of S3.1. The exemption of S3.1.1(e) would also apply to the 'center console' depicted in your diagram, since it also lies below the point at which a vertical line is tangent to the rearmost surface of the panel. The area labeled section A in your diagram is covered by the standard and thus would have to meet the requirements of S3.1; If you need further information, please let me know. Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam1022OpenMs. Claire Cannon, Center for Auto Safety, Post Office Box 7250, Washington, DC 20044; Ms. Claire Cannon Center for Auto Safety Post Office Box 7250 Washington DC 20044; Dear Ms. Cannon: This is in reply to your letter of February 14, 1973, concerning ou plans for publicizing the new Federal odometer requirements.; To begin with your third question, the NHTSA does not have th authority to require State departments of motor vehicles to notify the public of the odometer requirements. Because the participation of the States is voluntary, and not subject to regulation, we have not attempted to instruct the States in our regulatory notices. The approach you suggested, of sending notice of the Federal law with the auto registration cards, would be useful, particularly in States whose forms cannot be readily converted to contain the disclosure statement. This is one of the publicity measures that we are discussing with the States at the present time.; In the short run, we are going to have to rely on the public media t distribute information about the requirements. We issued press releases upon issuance of the notices establishing the requirement, and have been encouraging the press to highlight the problems of odometer tampering and to tell of the existence of the disclosure requirements. These efforts fall short, however, of providing the type of general coverage needed for regulations having a national effect. It is likely that most consumers will learn of the requirements from automobile dealers, most of whom have been advised of the requirements by their national dealer associations.; The problem of odometer fraud deserves full exposure, and we intend t do what we can to expose it. The scale of our long term efforts, however, including the question of the use of TV spots, is a matter that has not been resolved as yet.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam5061OpenMr. Kevin R. Boyne Chief Engineer Dynamics and Durability Engineering Transportation Research Center Inc. East Liberty, OH 43319-0367; Mr. Kevin R. Boyne Chief Engineer Dynamics and Durability Engineering Transportation Research Center Inc. East Liberty OH 43319-0367; "Dear Mr. Boyne: This responds to your letter requesting clarification of the requirements of S4.2.1 of Standard No. 114, Theft Protection. That section sets forth new requirements relating to key removal, which became effective on September 1, 1992. Your letter asks whether a vehicle which operates in the following manner would meet the requirements: Initial Condition - Engine running and shift lever positioned in 'drive'. Action - The operator depresses the thumb button on the left side of the shift lever and moves the shift lever to the 'park' position. Point of Concern - As long as the thumb button is held in the depressed position, the ignition key can be rotated to the lock position and removed. Still holding the thumb button, the shift lever can later be moved to any position. Removal of the key will only occur in the 'park' position. As discussed below, it is our opinion that a system which operates in the manner you described would comply with S4.2.1 of the standard for vehicles manufactured before September 1, 1993, but not for vehicles manufactured after that time. This assumes, for vehicles manufactured before September 1, 1993, that steering is prevented after removal of the key. It also assumes that the system does not otherwise permit removal of the key when the transmission is not locked in park. By way of background information, the National Highway Traffic Safety 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 meet applicable standards. The following represents our opinion based on the facts provided in your letter. Section S4.2.1 of Standard No. 114 states: Except as provided in S4.2.2(a) and (b), the key-locking system required by S4.2 in each vehicle which has an automatic transmission with a 'park' position shall prevent removal of the key unless the transmission or transmission shift lever is locked in 'park' or becomes locked in 'park' as the direct result of removing the key. The system which you describe appears to permit removal of the key in a situation when both the transmission and transmission shift lever are not locked in 'park' and when they do not become locked in 'park' as the direct result of removing the key. This conclusion follows from the fact that, following the removal of the key, the shift lever can be moved to any position. Therefore, the system you describe would not comply with S4.2.1 unless one of the exceptions in section S4.2.2(a) and (b) apply. The exception set forth in S4.2.2(a) only applies in the event of electrical failure and is therefore not relevant to the system you describe. S4.2.2(b) of Standard No. 114 reads as follows: (b)(1) Notwithstanding S4.2.1, each vehicle specified therein may have a device which, when activated, permits moving the transmission shift lever from 'park' after the removal of the key provided that steering is prevented when the key is removed. (2) For vehicles manufactured on or after September 1, 1993, the means for activating the device shall either be operable by the key, as defined in S3, or by another means which is covered by a non-transparent surface which, when installed, prevents sight of and activation of the device and which is removable only by use of a screwdriver or other similar tool. NHTSA included this second exception to allow for a manual override of the transmission shift lock so that a disabled vehicle could be moved. The requirement that such devices either be operable by the key or by another means which is covered by a non-transparent surface originally had an effective date of September 1, 1992. However, after considering petitions for reconsideration, NHTSA decided to provide an additional year's leadtime, noting that this would lessen the impacts associated with such redesign of the emergency override buttons of a number of systems. While the agency was primarily concerned about emergency override buttons in drafting S4.2.2(b), it is our opinion that the language in (b)(1) is sufficiently broad to include the thumb button on a transmission shift lever itself, i.e., the button can be considered a device which, when activated, permits moving the transmission shift lever from 'park' after the removal of the key. Therefore, assuming that steering is prevented after the removal of the key, the system you describe would come within the exception provided in S4.2.2(b)(1). Effective September 1, 1993, of course, such a device must also meet the requirements set forth in S4.2.2(b)(2) in order to come within this exception to S4.2.1. The system you describe would not fall within the exception at that time. The thumb button is not 'the key, as defined in S3.' In addition, the thumb button is not 'covered by a non-transparent surface which, when installed, prevents sight of and activation of the device and which is removable only by use of a screwdriver or other similar tool.' Therefore, based on the information you have provided, the system would not comply with S4.2.1 for vehicles manufactured on or after September 1, 1993. 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, Paul Jackson Rice Chief Counsel"; |
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ID: aiam0799OpenMr. J. C. Eckhold, Director, Automotive Safety Office, Ford Motor Company, The American Road, Dearborn, MI 48121; Mr. J. C. Eckhold Director Automotive Safety Office Ford Motor Company The American Road Dearborn MI 48121; Dear Mr. Eckhold:This is in reply to your letter of July 26, 1972 concerning the adjustment of a tractor's fifth wheel under the test conditions proposed in Docket 70-17, Notice 5.; You state that it is not possible to load the tractor to its GVWR wit the tractor's nonsteerable axles and the trailer's axles at GAWR if the fifth wheel is set in more than one position. If this is the case, and the correct loading can be obtained with the fifth wheel in one position only, then only that position will be used in compliance testing. If more than one position can be used to produce the correct loading, the tractor must conform to the requirements of the standard with the fifth wheel at any such position.; Sincerely, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam0263OpenMr. E. W. Bernitt, Vice President Safety and Quality Assurance, American Motors Corporation, Jeep Corporation, 940 North Cove Boulevard, Toledo, OH 43601; Mr. E. W. Bernitt Vice President Safety and Quality Assurance American Motors Corporation Jeep Corporation 940 North Cove Boulevard Toledo OH 43601; Dear Mr. Bernitt: This is in reply to your letter of October 12, 1970, to Mr. Charles A Baker of this office in which you requested an interpretation of the phrase 'effective projected illuminated area.'; Class A turn signal lamps are required by Section S3.1 of Federal Moto Vehicle Safety Standard No. 108, which references SAE Standard J588d in Tables I and III for these lamps. The requirements for the illuminated area of a turn signal lamp are specified in J588d as follows:; >>>'The effective projected illuminated area measured on a plane a right angles to the axle of the lamp must not be less than 12 sq. in. for Class A and 3-1/2 sq. in. for Class B.'<<<; In the 45 degree visibility requirements, this standard further state 'To be considered visible, the lamp must provide an unobstructed projected illuminated area of outer lens surface, including reflex,...'.; Our interpretation of effective projected illuminated area follows: Th effective projected illuminated area is that area of the lens measured on a plane at right angles to the axle of the lamp, including reflex reflector, which is not obstructed by an opaque object such as a mounting screw, mounting ring, or an ornamental basel or trim.; The above interpretation allows the area of rings or othe configurations (raised portions) molded in the lens to be considered part of the total effective area, even if this area does not contribute significantly to the total light output.; Sincerely, Roger Crampton, Director, Office of Operating Systems, Moto Vehicle Programs; |
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ID: aiam5431OpenMr. Jerry Miller Director of Operations Associated Leasing Handicapable Vans 12117 Riverwood Drive Burnsville, MN 55337; Mr. Jerry Miller Director of Operations Associated Leasing Handicapable Vans 12117 Riverwood Drive Burnsville MN 55337; Dear Mr. Miller: This responds to your letter of May 31, 1994 requesting confirmation that 'there are no rules or regulations on wheelchair tie downs for vehicles other than school buses.' You are correct that Federal motor vehicle safety standard No. 222, School Bus Passenger Seating and Crash Protection, which includes requirements for wheelchair securement devices, applies only to school buses. However, while none of the safety standards apply to wheelchair securement devices for vehicles other than wheelchairs, the manufacturer of the product is subject to federal requirements concerning the recall and remedy of products with defects related to motor vehicle safety (49 U.S.C. 30118-30121). The agency does not determine the existence of defects except in the context of a defect proceeding. You should also be aware that the Department of Transportation has issued a final rule implementing the transportation provisions of the Americans with Disabilities Act. This final rule includes requirements for wheelchair securement devices installed in vehicles required to be accessible by this rule. A copy of the final rule is enclosed with this letter. If you have further questions on these regulations, please contact Mr. Irv Chor of the Federal Transit Administration. Mr. Chor's card is attached to the final rule. I hope you find this information helpful. If you have any other questions concerning NHTSA regulations, 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: aiam1921OpenMr. Phil Martinez, Trailmaster Tanks, Inc., P.O. Box 13137, Fort Worth, TX 76118; Mr. Phil Martinez Trailmaster Tanks Inc. P.O. Box 13137 Fort Worth TX 76118; Dear Mr. Martinez: This responds to Trailmaster Tank's May 14, 1975, request for discussion of what constitutes the manufacture of a trailer in cases where used components from an existing vehicle are involved.; In response to a similar request from the Truck Trailer Manufacturer Association, the National Highway Traffic Safety Administration recently prepared a comprehensive discussion of this subject, a copy of which is enclosed for your information.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
Request an Interpretation
You may email your request to Interpretations.NHTSA@dot.gov or send your request in hard copy to:
The Chief Counsel
National Highway Traffic Safety Administration, W41-326
U.S. Department of Transportation
1200 New Jersey Avenue SE
Washington, DC 20590
If you want to talk to someone at NHTSA about what a request for interpretation should include, call the Office of the Chief Counsel at 202-366-2992.
Please note that NHTSA’s response will be made available in this online database, and that the incoming interpretation request may also be made publicly available.