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: nht72-1.34OpenDATE: 03/29/72 FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA TO: Toyo Kogyo Detroit Office TITLE: FMVSS INTERPRETATION TEXT: This is in response to your letter of March 16, 1972, in which you ask whether the definition of "unloaded vehicle weight" is the same as that for "'curb weight' plus optional parts," and whether the definition of "gross vehicle weight" is the same as that for "maximum loaded vehicle weight." The two sets of definitions are expressed in substantially different terms. The new terms, "unloaded vehicle weight" and "gross vehicle weight rating" are more general than the older ones. The newer terms also eliminate some ambiguities in the definitions based on "curb weight," such as just what is (Illegible Word) by "standard equipment," and whether other vehicle fluids besides fuel, oil, and coolant should be included. Further, GVWR is a rating, not necessarily identical to any scale weight although some constraints have been placed on it in our Certification regulations (@ 567.4(g)(3)). Thus, although the two sets of definitions are somewhat similar in their application, they are different enough that each must be interpreted and used in its own terms. |
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ID: nht74-2.25OpenDATE: 05/10/74 FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA TO: Kelsey-Hayes Company TITLE: FMVSS INTERPRETATION TEXT: This will acknowledge receipt of Kelsey-Hayes' petition to add "after-stop" to the description of temperature range in S6.1.8.1 of Standard No. 121 and S7.4.2.1.2 of Standard No. 105a. The temperature range is in fact intended to describe the after stop temperature of the brakes, and the language of the sections will be clarified in the future. Yours truly, ATTACH. April 25, 1974 U. S. Department of Transportation, National Highway Traffic Safety Administration, Richard B. Dyson -- Assistant Chief Counsel RE: Requests for Interpretation -- FMVSS 105 (9/1/75) S7.4.2.1.2; FMVSS 121 S6.1.8.1; Your file numbers N40-30 (ZTV) and (TWH); Brake Burnish Procedure Dear Mr. Dyson: You have responded to our requests for interpretation on identical language in these subsections of these standards and advised that the word maximum would be deleted in the sentence ending in ". . . maintain a maximum temperature of 500 degrees F +/- 50 degrees F." We recommend one further clarification to eliminate ambiguity, namely, that the phrase "after-stop temperature" be added to the sentence, as follows: "If during any of the brake applications specified in , the hottest brake reaches 500 degrees F, make the remainder of the 500 applications from that speed except that a higher or lower speed shall be used as necessary to maintain an after-stop temperature of 500 degrees F +/- 50 degrees F." We further suggest that a notice be issued proposing this clarification. Very truly yours, John F. McCuen -- Attorney, KELSEY-HAYES COMPANY cc: W. T. Birge; D. Renner |
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ID: nht73-3.28OpenDATE: 02/15/73 FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA TO: Mr. Charles J. Simerlein TITLE: FMVSS INTERPRETATION TEXT: This is in reply to your letter of November 29, 1972, concerning the method in which a load is to be "secured in the luggage area" under the test procedures of Standard 208. I apologize for our delay. The intent of S8.1.1(a) is to place the load in the luggage area in such a way that it stays there during the test. The standard does not specify the manner in which the load is secured. A manufacturer may secure it in any reasonable manner. |
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ID: nht88-2.92OpenTYPE: INTERPRETATION-NHTSA DATE: 08/09/88 FROM: BLANCHE G. KOZAK TO: CHIEF COUNCIL LEGAL DEPT. U.S. DEPT. OF TRANSPORTATION TITLE: NONE ATTACHMT: ATTACHED TO LETTER DATED 06/09/89 FROM STEPHEN P. WOOD -- NHTSA TO BLANCHE KOZAK; REDBOOK A33 [2]; VSA 108 [A] [1] [A]; LETTER DATED 04/04/89 FROM NANCY L. BRUCE -- DOT TO CHESTER ATKINS -- HOUSE; LETTER DATED 03/29/89 FROM CHESTER G. ATKINS -- HOUSE TO NANCY BRUCE -- DOT, RE MRS. BLANCHE KOZAK; LETTER DATED 09/26/88 FROM BLANCHE KOZAK TO BERRY FELRICE; LETTER DATED 10/16/79 FROM EDWIN P. RIEDEL; REPORT UNDATED TEXT: Dear Sir/Madam; Please be informed that I spoke to Ms. Williams, Supervisor NHTSA, on Aug. 9, 1988 and was advised to request a written statement from the Legal Dept. in regards to the Cushman Vehicle, Model #404. It is my understanding that the "on-road Cushman Veh icle is classified as a motorcycle under the current definitions found in the Code of Federal Regulations, Vol. 49, Part 571.3." by Barry Felrice of the Dept. of Transportation on July 22, 1988 to Rep. James J. Florio. My question is in regards to the Model # 404 which is the Off-road design manufactured by O.M.C. Lincoln Cushman-Ryan and sold by The Sawtelle Bros. for on road use in the Commonwealth of Massachusetts. When and by whom was this vehicle authoruzed fo r on road use as a motor vehicle and not a motorcycle. This information was requested of me by my State Senator for the purpose of having it in writing to present to the committee in the process of filing a bill on the State Level to have these Cushman Vehicles regulated in the Commonwealth of Massachuset ts. My Husband was killed on a Cushman Model # 404 while working for the Lawrence General Hospital on Dec. 9, 1980. This vehicle was sold to the LGH for on road use, for further information you may refer to my report of the accident to NHTSA on June 11, 1988. Thank you very much for your anticipated response to my plea. Gratefully yours |
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ID: nht88-3.46OpenTYPE: INTERPRETATION-NHTSA DATE: 09/12/88 FROM: RUSSELL A. STORMS TO: NAC EXECUTIVE DIRECTOR OFFICE OF TRAFFIC OPERATIONS FEDERAL HIGHWAY ADMINISTRATION TITLE: NONE ATTACHMT: ATTACHED TO LETTER DATED 08/17/89 FROM STEPHEN P. WOOD -- NHTSA TO RUSSELL STORMS; REDBOOK A34; STANDARD 125; VSA 108[B]; LETTER DATED 09/23/88 FROM HARRY B. SKINNER -- DOT TO RUSSELL A. STORMS TEXT: Dear Sir or Madam: We are writing pursuant to Section IA-6 of the Manual on Uniform Traffic Control Devices to obtain recognition for a new device designed to warn motorists of a hazardous situation. We have a patent pending on a multiple-sided emergency traffic warning marker that is designed to be employed by a motorist immediately prior to the employment of flares or other warning devices. The marker is basically a tetrahedral configuration, cont oured and proportioned to ensure a warning display to oncoming vehicles when the marker is placed on a roadway surface (drawing attached). The marker is basically of a "bean bag" nature that is foldable and stackable for easy transportation and storage in the vehicle when not in use and which is of relatively low cost so that a plurality of markers may be economically carried and deployed b y the vehicle driver. It is seven (7) inches in height and made of reflective material. The primary advantage of this marker is that it can be employed quickly in the event of an emergency by a motorist and is not of an incendiary nature and can be safely stored in the passenger compartment of a vehicle. It is our opinion that this particu lar marker affords a measure of protection not available by other products currently available and would represent an improvement in traffic safety. In closing, if we intend to bring this product to market, it is our understanding that your organization is the appropriate forum for approval of this product. Please advise us of a proper course of action necessary to gain this approval. Thank you for your help. Sincerely, [DRAWING OMITTED] |
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ID: 19257.drnOpenMr. Robert L. Douglas Dear Mr. Douglas: This responds to your request for interpretation of how to test a floor panel complex joint in a school bus, as AmTran is considering a new floor design. As explained below, the National Highway Traffic Safety Administration (NHTSA) will address this issue in a final rule amending Standard No. 221, School bus body joint strength. As you are aware, in the FEDERAL REGISTER of November 5, 1998 (63 FR 59732), NHTSA published a final rule amending Standard No. 221. The final rule's effective date is May 5, 2001. The final rule addressed testing of curved or complex joints, such as that found in a school bus floor panel. NHTSA has received several petitions for reconsideration of the final rule to clarify test procedures for small, curved, and complex joints. NHTSA is presently reviewing the petitions, and expects to issue another final rule on Standard No. 221 that will address the issues raised. Because the issue you raised in your letter was raised by the petitioners, we will address your question in our response to petitions for reconsideration that will be published some time in the future. I hope this information is helpful. If you have any further questions, please feel free to contact Dorothy Nakama of my staff at this address or at (202) 366-2992. Sincerely, |
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ID: nht92-9.5OpenDATE: February 14, 1992 FROM: Paul Jackson Rice -- Chief Counsel, NHTSA TO: Gordon W. Didier, Esq. -- Butzel Long TITLE: None ATTACHMT: Attached to letter dated 1/22/92 from Gordon W. Didier to Office of the General Counsel, NHTSA TEXT: This responds to your request for an interpretation of Federal Motor Vehicle Safety Standard No. 118 Power Windows (49 CFR S571.118), on behalf of your client, a manufacturer of automobile sunroofs. As you noted in your letter, the agency has published a final rule amending Standard No. 118 in the April 16, 1991 edition of the Federal Register (56 FR 15290). You requested clarification of certain requirements in that final rule. The agency has received several petitions for reconsideration of the final rule amending Standard No. 118. The agency is currently reviewing the merits of each petition. The agency will issue a notice in the Federal Register granting and/or denying the petitions. In that notice, the agency will also address the concerns raised in your request for an interpretation on Standard No. 118. Please let us know if you have any questions about the issues raised in your letter after our response to the petitions for reconsideration has been published and you have had the opportunity to review it. If you need more information on this subject, please feel free to contact Dorothy Nakama of my staff at this address, or by telephone at (202) 366-2992. |
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ID: nht92-9.7OpenDATE: February 14, 1992 FROM: Paul Jackson Rice -- Chief Counsel, NHTSA TO: Cliff Chuang -- President, Prospects Corporation TITLE: None ATTACHMT: Attached to letter dated 1/22/92 from Cliff Chuang to Dorothy Nakama (OCC 6893; Std. 118)) TEXT: This responds to your request for an interpretation of Federal Motor Vehicle Safety Standard No. 118 Power Windows (49 CFR S571.118). As you noted in your letter, the agency has published a final rule amending Standard No. 118 in the April 16, 1991, edition of the Federal Register (56 FR 15290). You requested clarification of certain requirements in that final rule. The agency has received several petitions for reconsideration of the final rule amending Standard No. 118. One such petition is from your company. The agency is currently reviewing the merits of each petition. The agency will issue a notice in the Federal Register granting and/or denying the petitions. In that notice, the agency will also address the concerns raised in your request for an interpretation of Standard No. 118. Please let us know if you have any questions about the issues raised in your letter after our response to the petitions for reconsideration has been published and you have had the opportunity to review it. If you need more information on this subject, please feel free to contact Dorothy Nakama of my staff at this address, or by telephone at (202) 366-2992. |
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ID: nht72-6.29OpenDATE: 01/31/72 FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA TO: Universal Fire Apparatus Corporation TITLE: FMVSR INTERPRETATION TEXT: This is in reply to your letter of November 12, 1971, in which you state that you place a fire pump and body on a chassis which you purchase, and ask whether you are required to place a certification label or vehicle alteration label on the vehicle. It is unclear to us to what you refer by vehicle alteration label. However, based on the very limited information you have provided it appears that you are in final stage manufacturer under section 568.3 of the regulations governing "Vehicles Manufactured in two or More States" (49 CPR Part 568). As such you are required, pursuant to Section 568.6 to complete the vehicle so that it conforms to all applicable motor vehicle safety standards, and to certify compliance to those standards by affixing a certification label in the manner set forth in section 567.5 of the Certification regulations (49 CFR Part 567). Copies of both the Certification regulations and regulations governing "Vehicles Manufactured in Two or More States" are enclosed. If you have further questions please write. |
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ID: nht79-3.35OpenDATE: 07/17/79 FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA TO: Paul Schuil TITLE: FMVSS INTERPRETATION TEXT: This responds to your recent letter asking whether smoked, tinted and mirrored windows may legally be used on vehicles operating on U.S. highways. The Federal requirements for glazing materials on motor vehicles are set forth in the Federal Motor Vehicle Safety Standard No. 205 (49 CFR 571.205). This standard specifies performance requirements for the various types of glazing and also the locations in vehicles in which each glazing type may be used. Smoked, tinted and mirrored glazing may be used in certain vehicles in certain locations. For example, smoked glass may be used in side windows of trucks and buses. However, glazing material for use in any vehicle at levels requisite for driving visibility (e.g., windshields) must have a luminous transmittance of at least 70 percent. Most smoked glass would not pass this requirement. I am enclosing a copy of Safety Standard No. 205 for your information. If you have any questions after reviewing the standard, contact Hugh Oates of my office (202-426-2992). SINCERELY, HADCO ALUMINUM & METAL CORPORATION DEAR SIRS, I would like to know if smoked or tinted, & mirrored windows are legal on U.S. highways. I am talking about all four sides of a vehicle. Please send a response to: HADCO ALUMINUM AND METAL CORPORATION PAUL SCHUIL |
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.