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: aiam0721OpenMr. Leonardo Fioravanti, S.p.A. Carrozzeria Pininfarina, Casella Postale N. 295, 10100 Torino, Italy; Mr. Leonardo Fioravanti S.p.A. Carrozzeria Pininfarina Casella Postale N. 295 10100 Torino Italy; Dear Mr. Fioravanti: Thank you for your letter of May 25, 1972, inquiring about th applicability of Federal Motor Vehicle Safety Standard (FMVSS) No. 205, and FMVSS No. 302, to the rear windows of convertible cars.; In FMVSS No. 302, the convertible top is not intended to refer to th rear window, but has reference only to the overhead material. Flammability of the transparent glazing material is regulated by FMVSS No. 205.; Sincerely, Robert L. Carter, Associate Administrator, Motor Vehicl Programs; |
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ID: aiam1999OpenMr. Terrell T. Coleman, Codes and Standards Coordinator, Holiday Rambler Corporation, 311 Indiana Avenue, Wakarusa, Indiana 46573; Mr. Terrell T. Coleman Codes and Standards Coordinator Holiday Rambler Corporation 311 Indiana Avenue Wakarusa Indiana 46573; Dear Mr. Coleman: I am writing in response to your letter of June 23, 1975, whic inquired about the status of proposed Federal Motor Vehicle Safety Standard No. 120, *Tire Selection and Rims for Motor Vehicles Other Than Passenger Cars*.; The NHTSA expects to issue Standard No. 120 in the near future. It wil not become effective September 1, 1975. An effective date which allows adequate lead time for manufacturers to prepare for compliance will be specified in a *Federal Register* notice when the rule is issued. Your second question, concerning the responsibility for providing GAWR and GVWR information for motor homes manufactured by you with chassis supplied by other manufacturers, will also be answered in that notice.; Sincerely, Frank A. Berndt, Acting Chief Counsel |
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ID: aiam5173OpenMr. Bob Brinton Friction Advisory Service 2001 Broadway Street Vancouver, WA 98663-3326; Mr. Bob Brinton Friction Advisory Service 2001 Broadway Street Vancouver WA 98663-3326; "Dear Mr. Brinton: This responds to your letter inquiring about th legality of an auxiliary parking system in addition to the spring parking brake system. According to your letter, you are familiar with certain refuse type vehicles with right hand side drive that are equipped with an I.C.C. flip switch valve or a push pull valve. These valves permit a driver to temporarily park the vehicle while the driver leaves the vehicle and picks up trash. You explained that while the auxiliary brake system is applied, the spring brakes are not applied to help the spring avoid extreme wear cycles. You asked whether the auxiliary brake system is legal under Standard No. 121. In your letter, you indicate your view that these auxiliary systems do not comply with the parking brake requirements in S5.6.3 of Standard No. 121, Air Brake Systems. Based on our understanding of the brake system you describe, I am pleased to have this opportunity to explain our regulations to you. By way of background information, the National Traffic and Motor Vehicle Safety Act ('Safety Act') requires this agency, the National Highway Traffic Safety Administration (NHTSA), to promulgate motor vehicle safety standards that specify performance requirements for new motor vehicles and items of motor vehicle equipment. One such standard is Standard No. 121, which establishes performance and equipment requirements for braking systems on vehicles equipped with air brake systems, and applies to almost all new trucks, buses, and trailers equipped with air brake systems. The purpose of the standard is to ensure safe braking performance under normal and emergency conditions. A vehicle equipped with air brakes is required to comply with the requirements set forth in Standard No. 121. Among other things, S5.6 of the Standard requires air-braked vehicles to be equipped with a parking brake system that meets specified performance requirements. The requirements in Standard No. 121, however, do not preclude the installation of a braking system in addition to the systems installed to comply with the Standard's requirements. Accordingly, the agency would not consider the requirements of S5.6 to prohibit an auxiliary parking brake system in addition to the brake systems required to comply with Standard No. 121. Nevertheless, as an item of motor vehicle equipment subject to the requirements in sections 151-159 of the Safety Act concerning the recall and remedy of products with defects related to motor vehicle safety, an auxiliary parking brake system should be built in such a manner that the public is protected against unreasonable risk of injury that might occur as a result of its design, construction, or performance. Please note that this interpretation is consistent with the agency's long- standing view about the use of auxiliary parking brake systems. I am enclosing a December 9, 1976 interpretation letter to Mr. Leon Steenbock which addressed this issue. I hope this information is helpful. If you have any questions about NHTSA's safety standards, please feel free to contact Marvin Shaw at this address or by telephone at (202) 366-2992. Sincerely, John Womack Acting Chief Counsel Enclosure"; |
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ID: aiam0371OpenMr. Nathan Sagan, 949 Central Avenue, Albany, NY (sic); Mr. Nathan Sagan 949 Central Avenue Albany NY (sic); Dear Mr. Sagan: This is in reply to your request made to the Regional Administrator o the National Highway Traffic Safety Administration, concerning the applicability of the Tire Identification and Record Keeping regulation (49 CFR Part 574) to Cushman golf carts.; Golf carts are not considered to be motor vehicles within the meanin of the regulation or the National Traffic and Motor Vehicle Safety Act and therefore the regulation is not applicable to tires sold with these vehicles.; Sincerely, Lawrence R. Schneider, Acting Chief Counsel |
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ID: aiam5489OpenMr. G. Brandt Taylor President Day-Night Mirrors, Inc. 36 Barnes Hill Road Berlin, MA 01503; Mr. G. Brandt Taylor President Day-Night Mirrors Inc. 36 Barnes Hill Road Berlin MA 01503; Dear Mr. Taylor: This responds to your letter asking about th requirements applicable to multiple reflectance mirrors in Federal Motor Vehicle Safety Standard (FMVSS) No. 111, Rear View Mirrors. You stated that your mirror can change its reflectivity either by mechanically rotating a shaft or by actuating an electrical motor. By way of background information, the National Highway Traffic Safety Administration (NHTSA) has the authority to issue safety standards for new motor vehicles and new items of motor vehicle equipment. NHTSA does not, however, approve or certify any vehicles or items of equipment. Instead, each manufacturer is responsible for 'self-certifying' that its products meet all applicable safety standards. The agency periodically tests vehicles and items of equipment for compliance with the standards. FMVSS No. 111 specifies requirements for the performance and location of rearview mirrors. Section S11, which specifies requirements for mirror construction, provides in relevant part that All single reflectance mirrors shall have an average reflectance of at least 35 percent. If a mirror is capable of multiple reflectance levels, the minimum reflectance level in the day mode shall be at least 35 percent and the minimum reflectance level in the night mode shall be at least 4 percent. A multiple reflectance mirror shall either be equipped with a means for the driver to adjust the mirror to a reflectance level of at least 35 percent in the event of electrical failure, or achieve such reflectance automatically in the event of electrical failure. You asked several questions about the requirement for adjusting the mirror in the event of electrical failure. You first asked if a manual override knob could be removable. You then asked whether a removable manual override could be supplied by the car manufacturer along with the car keys or with the owner's manual for insertion into the mirror and use only in the event of an electrical failure. You also asked about whether 'west coast' mirrors and mirrors on trailer trucks could have a removable manual override. The answer to each of your questions is that a removable manual override knob would not be permitted. In the preamble to the final rule amending the mirror construction requirements in FMVSS No. 111, NHTSA stated that the agency's goal is to assure that multiple reflectance mirrors are capable of providing adequate images at all times during the vehicle's operation, including electrical failure situations where the mirror is unpowered. (see 56 FR 58513, November 20, 1991) The manual override knob you discuss would serve as the means for the driver to adjust the mirror's reflectance level. However, a removable manual override knob would not always serve this purpose, since it would not necessarily always be with the mirror. We are concerned that a removable override device may become lost or otherwise not available when a mirror's reflectance needs to be adjusted. Accordingly, since the agency's goal of providing adequate images at all times during the vehicle's operation would only be achieved by requiring this device to be permanent, a removable override would not be permitted. I hope this information is helpful. If you have any other questions, please contact Marvin Shaw of my staff at this address or by phone at (202) 366-2992. Sincerely, Philip R. Recht Chief Counsel; |
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ID: aiam1976OpenMr. Robert L. Asbury, President, Premier Seat and Accessory Co., 2350 Pleasant Avenue, Hamilton, OH 45015; Mr. Robert L. Asbury President Premier Seat and Accessory Co. 2350 Pleasant Avenue Hamilton OH 45015; Dear Mr. Asbury: This is in response to your letter dated March 25, 1975, requesting a opinion as to whether safety helmets for firemen are covered by Federal Motor Vehicle Safety Standard No. 218, *Motorcycle Helmets*.; The answer to your question is no. Firemen's helmets are not designe primarily to protect their wearers in the event of a motor vehicle accident, but are intended to provide protection from falling debris and sparks while firefighting. Consequently, different design criteria apply and the designs commonly used differ rather greatly in appearance and performance from most motorcycle helmets.; Sincerely, James C. Schultz, Chief Counsel |
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ID: aiam2659OpenMr. James Tydings, Thomas Built Buses, Inc., 1408 Courtesy Road, P.O. Box 2450, High Point, NC 27261; Mr. James Tydings Thomas Built Buses Inc. 1408 Courtesy Road P.O. Box 2450 High Point NC 27261; Dear Mr. Tydings: This responds t your August 19, 1977, letter asking whether Standar 217, *Bus Window Retention and Release*, allows the identification of the rear emergency door located anywhere on the top half of the door.; The standard in S5.5.3 requires the emergency door identification to b located at the top of or directly above the emergency exit....' The National Highway Traffic Safety Administration interprets this requirement to mean that the emergency door label must be located on the top half of the door or directly above the door. The label location as depicted in the picture you enclosed with your letter appears to comply with the requirements of S5.5.3.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam0664OpenMr. S. A. Heenan, Director, Research & Development, Stimsonite Division, Amerace - Esna Corporation, 3445 North Kimball Avenue, Chicago, IL 60618; Mr. S. A. Heenan Director Research & Development Stimsonite Division Amerace - Esna Corporation 3445 North Kimball Avenue Chicago IL 60618; Dear Mr. Heenan: In your letter of February 4 to Mr. Schneider you discussed difference between SAE Standard J594d, March 1967, *Reflex Reflectors,* and its successor J594e, March 1970. You asked 'whether relief can be granted from the unnecessary specular restriction appearing in Federal Motor Vehicle Safety Standard No. 108 because of its inclusion of J594d rather than J594e.'; We have reviewed your letter and the Administrator has determined tha the issue you raised merits initiation of rulemaking. I enclose a copy of a notice proposing an amendment to Standard No. 108 to substitute SAE J594e as the referenced requirement for reflex reflectors.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam5466OpenMr. R. F. Wareham Technical Director Total Vehicle Security, Ltd. 1 Friarn Lawn Bridgwater Somerset TA6 3LL England; Mr. R. F. Wareham Technical Director Total Vehicle Security Ltd. 1 Friarn Lawn Bridgwater Somerset TA6 3LL England; Dear Mr. Wareham: We have received your letter of December 9, 1994, t John Womack, the Acting Chief Counsel who responded to David Lee on January 26, 1993. This will confirm that his opinion regarding the 'Third Brake Light Conditions Sensor' remains the official position of this agency. We shall be pleased to meet with you when you come to Washington late in January. You may phone Taylor Vinson of this Office to make arrangements (202- 366-5263). We will be particularly interested in learning more about how the device 'will be marketed as a D.I.Y. installation by the car owner.' Sincerely, Philip R. Recht Chief Counsel; |
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ID: aiam2209OpenMr. Lonnie Goddard, Northern Coach, Inc., Box 190, Auburndale, WI 54412; Mr. Lonnie Goddard Northern Coach Inc. Box 190 Auburndale WI 54412; Dear Mr. Goddard: I am writing to confirm your telephone conversation of February 25 1976, with Mark Schwimmer of this office, concerning the certification of school buses.; As Mr. Schwimmer explained, this agency does not certify or otherwis issue advance approvals of motor vehicles or motor vehicle equipment. Certification, under the applicable law and regulations, must be done by the vehicle manufacturer, including a final-stage manufacturer such as you. Your certification obligation, as a final stage manufacturer of school buses, is met if you fulfill the requirements of 49 CFR Part 567, with which I understand you are already familiar.; An information sheet entitled 'Where to Obtain Federal Motor Vehicl Safety Standards and Regulations' is enclosed for your convenience. Please write if we can be of any further assistance.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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Request an Interpretation
You may email your request to Interpretations.NHTSA@dot.gov or send your request in hard copy to:
The Chief Counsel
National Highway Traffic Safety Administration, W41-326
U.S. Department of Transportation
1200 New Jersey Avenue SE
Washington, DC 20590
If you want to talk to someone at NHTSA about what a request for interpretation should include, call the Office of the Chief Counsel at 202-366-2992.
Please note that NHTSA’s response will be made available in this online database, and that the incoming interpretation request may also be made publicly available.