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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| search results table | |
ID: aiam1597OpenMr. Bernard E. Wuthrich, Pan Commercial, 108 Grove Street, Worcester, MA., 01605; Mr. Bernard E. Wuthrich Pan Commercial 108 Grove Street Worcester MA. 01605; Dear Mr. Wuthrich: This is in reply to your letter of August 27, 1974 asking for clarification of the National Traffic and Motor Vehicle Safety Act.; You are correct in your impression that under section 103(d) of the Ac 'no state legislation can be more stringent than the Federal ruling.' Under paragraph S4.1.126 of Standard No. 108, effective October 14, 1974, 'a motor-driven cycle whose speed attainable in 1 mile is 30 mph or less need not be equipped with turn signal lamps.' This means that as of that date, only motor-driven cycles whose maximum speed exceeds 30 mph are required to be manufactured with turn signal lamps. Lower- speed cycles may continue to be provided with them if the manufacturer chooses, but a State cannot require him to do so. This is the result of the preemptive effect of section 103(d).; Yours truly, Richard B. Dyson, Acting Chief Counsel |
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ID: aiam3400OpenMr. Brian Gill, Manager, Certification Department, American Honda Motor Co., Inc., 100 W. Alondra Blvd., P.O. Box 50, Gardena, CA 90247; Mr. Brian Gill Manager Certification Department American Honda Motor Co. Inc. 100 W. Alondra Blvd. P.O. Box 50 Gardena CA 90247; Dear Mr. Gill: This responds to your recent letter regarding an emergency lockin retractor design which incorporates a secondary locking mechanism that is activated by webbing movement. The primary locking mechanism of the retractor is sensitive to both vehicle deceleration and webbing movement. You ask whether the secondary locking mechanism must be tested separately for compliance with Safety Standard No. 209, or whether it is sufficient that the retractor as a whole comply with the standard.; The secondary locking mechanism does not have to be tested separatel since it would be viewed by the agency as a voluntary system. I am enclosing a letter of interpretation on this same subject which was issued by the agency in February 1981 to Toyota Motor Company. I am also enclosing a copy of a letter of interpretation issued to the United States Testing Company regarding the application of Safety Standard No. 209 to dual- sensitive retractors. This second letter might also be of interest to you since you state that the primary locking mechanism on the Honda retractor is sensitive to both vehicle deceleration and webbing movement.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam3953OpenMr. Ernest Astle, Purchasing Agent, Alco Manufacturing Company, P.O. Box 724, Logan, UT 84321; Mr. Ernest Astle Purchasing Agent Alco Manufacturing Company P.O. Box 724 Logan UT 84321; Dear Mr. Astle: This responds to your letter to Steve Kratzke of my staff asking for a interpretation of the requirements of Standard No. 302, *Flammability of interior materials* (49 CFR 571.302). Specifically, you asked if the requirements of that standard apply to aftermarket seat covers. While the standard applies only to new motor vehicles, its requirements do indirectly affect some aftermarket seat covers. As explained in greater detail in the attached letter to Mr. Cederbaum regarding the same issue, rendering inoperative equipment or elements of design installed in a vehicle pursuant to the Federal motor vehicle safety standards is prohibited if done by certain commercial enterprises, but is permitted if done by the vehicle owner. Thus, if a seat cover in a complying vehicle were replaced with a noncomplying seat cover by one of those enterprises, that act would violate the above prohibition. The same act, if done by the owner, would not be a violation.; Should you need further information or have any further questions i this area, please contact Mr. Kratzke at this address or by telephone at (202) 426-2992.; Sincerely, Jeffrey R. Miller, Chief Counsel |
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ID: aiam2641OpenMr. Samuel W. Alderson, President, Humanoid Systems, 747 East 223rd Street, Carson, CA 90745; Mr. Samuel W. Alderson President Humanoid Systems 747 East 223rd Street Carson CA 90745; Dear Mr. Alderson: This responds to your June 3, 1977, request for confirmation that 572.7(b) of Part 572, *Anthropomorphic Test Dummy* (49 CFR 572), specifies a minimum time period during which the pendulum used in testing may not reverse direction rather than an exact time.; Your interpretation is correct. The specification that the pendulu 'shall not reverse direction until T=123 ms' means that reverse travel must not occur earlier than 123 milliseconds after chordal displacement begins. The agency believes that this language can be improved and intends to clarify it at the next opportunity.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam5184OpenMr. Berkley C. Sweet Executive Vice President School Bus Manufacturers Institute 7508 Ben Avon Road Bethesda, MD 20817; Mr. Berkley C. Sweet Executive Vice President School Bus Manufacturers Institute 7508 Ben Avon Road Bethesda MD 20817; "Dear Mr. Sweet: This responds to your letter requesting definitions o primary, preprimary, and secondary school students. You write in response to our July 28, 1992 letter to you in which we state that the National Traffic and Motor Vehicle Safety Act, 15 U.S.C. 1581, et seq. (Safety Act), defines a school bus as a vehicle that is 'likely to be significantly used for the purposes of transporting primary, preprimary, or secondary school students to or from such schools or events related to such schools' (emphasis added). The terms primary, preprimary, and secondary school are not defined in the Safety Act or in the legislative history of the Act. However, NHTSA has historically interpreted 'preprimary school' to refer to kindergarten, nursery schools and Head Start facilities. 'Primary school' refers to elementary school, and 'secondary school' refers to high school. I have enclosed a copy of our March 20, 1990 letter to Mr. Cadwallader Jones that discusses whether various institutions (e.g., church schools and colleges) are considered 'schools' under the Safety Act. The various states may have their own definitions of a 'school' for determining the use requirements for school vehicles. Therefore, you should check with the state where questions of school vehicle use are at issue. I hope the above information will be of assistance to you. If you have any further questions regarding this matter, please feel free to contact Walter Myers of my staff at this address or at (202) 366-2992. Sincerely, John Womack Acting Chief Counsel Enclosure"; |
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ID: aiam0386OpenStephen F. Hefner, Esq, Nance, Caston, Hefner and Green, Attorneys-At-Law, 421 North Crockett Street, Sherman, TX 75090; Stephen F. Hefner Esq Nance Caston Hefner and Green Attorneys-At-Law 421 North Crockett Street Sherman TX 75090; Dear Mr. Hefner: This is in reply to your letter of May 20, 1971, concerning a marketin practice used by your client, Hale Trailer Sales, Inc., which consists of allowing purchasers of new trailers to specify that the trailer be delivered with either new or used tires. When used tires are chosen, you indicate that they are for the limited purpose of delivering the trailer to the purchaser, and are usually replaced by him with other tires. You further indicate that this practice is widespread in the particular industry.; You ask in your letter whether the Tire Identification an Recordkeeping regulations (49 CFR Part 574) apply to the trailers that are sold equipped with used tires. The answer to this question is no. However, as you apparently realize, trailers sold with new tires that have been manufactured on or after May 22, 1971, are subject to the regulation.; Your letter also discusses the possibility of future requirements fo trailer tires, and suggests three possible courses of action under such requirements by which trailers might be sold with used tires. An Advance Notice of Proposed Rulemaking concerning multipurpose passenger vehicle, truck, bus, motorcycle, and trailer tires was published October 14, 1967, (32 F.R. 14279) and a public meeting was held on the subject in June 1970. Since that time there has been no public issuance concerning this matter, and it is thus impossible to send you the proposed rule you requested. The matter is under active consideration within the agency, however, and the proposed requirements should be issued in the near future.; The proposals will solicit comments from interested persons, which wil be considered before any final regulations are issued. Your comments and any additional suggestions you might have would be appreciated in response to these proposals.; If you have additional questions, please feel free to write. Sincerely, Lawrence R. Schneider, Acting Chief Counsel |
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ID: aiam2211OpenEjner J. Johnson, Administrator, Maryland Department of Transportation, Motor Vehicle Administration, 6601 Ritchie Highway, N.E., Glen Burnie, Maryland 21062; Ejner J. Johnson Administrator Maryland Department of Transportation Motor Vehicle Administration 6601 Ritchie Highway N.E. Glen Burnie Maryland 21062; Dear Mr. Johnson: This is in response to your letter of January 26, 1976, to Mr. Fre Vetter, expressing your concern about Federal Motor Vehicle Safety Standard (FMVSS) No. 115, Vehicle Identification Numbers (VINs).; The National Highway Traffic Safety Administration (NHTSA) is wel aware of the importance of the VIN and its use in requirements for certification, defect investigation, recall campaigns, inspection and registration. We are also well aware of its importance to other users such as State administrations, law enforcement agencies, insurance companies and vehicle manufacturers. The VIN is crucial to the identification of stolen, junked and recycled vehicles.; It was NHTSA's intention with the initial issuance of FMVSS No. 115, t include within its scope all aspects of vehicle numbering relative to the vehicles to which it applied, and to leave any aspects for which there were no specific requirements to the discretion of the manufacturers until such requirements could be issued. This, of course, is the basis of our position that any state rules in this area must be the same as the Federal standards.; We agree, however, that the VIn may be more effective if it i standardized in structure, format, and information content. The NHTSA, though its personnel who are members of the Society of Automotive Engineers and International Standards Organization Committees, has been participating in the efforts to develop a worldwide VIN system for several years. The NHTSA plans to issue in the next few months an NPRM to amend FMVSS No. 115 that will specify requirements for a standardized, uniform identification numbering system for all motor vehicles on a worldwide basis. We welcome all help and recommendations in this action.; I sincerely hope that VESC will provide comments and recommendations t the docket as we proceed in our rulemaking action.; Sincerely, James B. Gregory, Administrator |
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ID: aiam3816OpenMr. R. G. Brown, Chief Engineer, Materials Engineering, Wagner Division, McGraw-Edison Company, 18448 Craig Road, St. Louis, MO 63146; Mr. R. G. Brown Chief Engineer Materials Engineering Wagner Division McGraw-Edison Company 18448 Craig Road St. Louis MO 63146; Dear Mr. Brown: This responds to your letter concerning Safety Standard No. 116, *Moto Vehicle Brake Fluids*. You asked whether paper labels on brake fluid containers are sufficient to comply with the 'indelibly marked' requirements of the standard. As discussed below, the answer to your question is no.; By way of background information, I would note that NHTSA does no grant 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 determine that its motor vehicles or motor vehicle equipment comply with applicable safety standards. The following represents our opinion based on the facts provided in your letter.; Section S5.2.2.2 of Standard No. 116 states: >>>Each packager of a brake fluid shall furnish the followin information clearly and indelibly marked on each brake fluid container. . . .<<<; It is our opinion that this section requires the relevant informatio to be marked directly on the brake fluid container and not merely on a label, whether paper or of some other material, that is affixed to the container. This is clear both from the plain language of the section and from the Federal Register notices proposing and adopting that language.; In a notice of proposed rulemaking published on September 30, 1970 NHTSA proposed the following language as part of the packaging and labeling requirements for motor vehicle brake fluids:; >>>S4.2.2.2 Each packager of brake fluid shall furnish to eac distributor or dealer to whom he sells brake fluid, the following information clearly and indelibly marked on each brake fluid container, or on a label or tag firmly attached to each such container. . . . 35 FR 15229, 15231.<<<; The final rule, published on June 24, 1971, did not adopt the propose alternative of permitting the information to be provided on a label or tag firmly attached to the container, but instead required the information to be clearly and indelibly marked on each brake fluid container. The language as adopted, which is very similar to the current language, was:; >>>S5.2.2.2 Each packager of motor vehicle brake fluid shall furnis the following information clearly and indelibly marked on each brake fluid container. . . . 36 FR 11987, 11989.<<<; If you have any further questions, please let me know. Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam0739OpenMr. Loy Rosner, Sales Manager, Checker Motors Sales Corporation, 35-30 38th Street, Long Island City, New York 11101; Mr. Loy Rosner Sales Manager Checker Motors Sales Corporation 35-30 38th Street Long Island City New York 11101; Dear Mr. Rosner: This is in reply to your letter o May 25, 1972, asking whether you, a a selling dealer, may install steel-belted radial ply tires in an 8-passenger Checker taxicab. You state that the vehicle is normally delivered to you with tires having the 'O' load range.; Federal Motor Vehicle Safety Standard No. 110 (49 CFR 571.110, cop enclosed) requires each passenger car to be equipped at the time of sale to a first purchaser with tires if certain minimum load carrying capacity, based on the weight of the vehicle. Any steel-belted radial ply tire that meets these load carrying requirements with respect to your vehicles may be installed by a selling dealer.; Radial tires of similar of Related sizes, but of different manufacture however, may have different load ratings. We suggest, therefore, that you contact Checker Motor Corporation for their recommendations as to which radial ply tires may be installs on these vehicles without adversely affecting the vehicle's conformity with Motor Vehicle Safety Standard No. 110.; Yours truly, Richard B. Dyson |
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ID: aiam2704OpenMr. Stanley Brajer, Project Engineer, Ellcon National, Inc., P.O. Box 307, Totowa, NJ 07512; Mr. Stanley Brajer Project Engineer Ellcon National Inc. P.O. Box 307 Totowa NJ 07512; Dear Mr. Brajer: This responds to your September 2, 1977, letter concerning th applicability of Standard No. 217, *Bus Window Retention and Release*, to a thermopane driver's window in a bus.; In response to your first question, the window to which you refer i required to comply with the requirements of the standard. The fact that it is a driver's window does not exempt it from the coverage of the standard.; Your second question asks how to test thermopane glazing. According t our enforcement staff, testing of thermopane windows can be conducted using the same criteria used for other window glazing. By following the procedures established in S5.1 of the standard, you should be able to accurately test thermopane glazing.; Sincerely, Joseph J. Levin,Jr., 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.