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: 77-1.19OpenTYPE: INTERPRETATION-NHTSA DATE: 02/08/77 FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA TO: Emilio Noriega TITLE: FMVSS INTERPRETATION TEXT: This responds to your November 3, 1976, question whether Standard No. 121, Air Brake Systems, prohibits the installation in a towing vehicle of a service brake control that is designed to permit separate, sequential, or simultaneous actuation of the service brake systems of the towing vehicle and any towed vehicle. Assuming that the valve for the towing vehicle represents a "split" service brake system as specified in S5.7 of Standard No. 121, such a service brake control design would not conflict with the Standard's requirements. Of course, the actual compliance of any vehicle with Standard No. 121 depends on the actual installation and performance of the system as well as its design. I would like to note that the agency is not endorsing the service brake control in question by the issuance of this interpretation letter. In fact, the agency is unsure about the effect the control may have on safe braking in a panic situation. Any test information that you or a vehicle manufacturer may care to provide would be appreciated. |
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ID: 77-2.15OpenTYPE: INTERPRETATION-NHTSA DATE: 04/18/77 FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA TO: AM General Corporation TITLE: FMVSS INTERPRETATION TEXT: This responds to your oral request of March 28, 1977, for clarification of the language of S5.4.1 of Standard No. 217, Bus Window Retention and Release. In particular, you ask whether the long side of a rectangular roof exit is required to be parallel to the center line of a bus. S5.4.1 requires that an exit provide "an opening large enough to admit unobstructed passage, keeping a major axis horizontal at all times, of an ellipsoid generated by rotating about its minor axis an ellipse having a major axis of 20 inches and a minor axis of 13 inches." Further, S5.2.1 of the standard states that a roof exit shall meet these requirements when the bus is overturned on either side. The requirement that the major axis be kept horizontal while the bus is on its side means that the major axis, and therefore the long side of the rectangular roof exit, would be parallel to the center line or the side wall of a bus. Sincerely, |
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ID: 77-4.14OpenTYPE: INTERPRETATION-NHTSA DATE: 10/07/77 FROM: AUTHOR UNAVAILABLE; J. J. Levin, Jr.; NHTSA TO: Wisconsin School Bus Association TITLE: FMVSS INTERPRETATION TEXT: This responds to your August 29, 1977, letter requesting an interpretation of Standard No. 222, School Bus Passenger Seating and Crash Protection, that would permit the measurement of seat spacing at any point along the width of the seat back. The National Highway Traffic Safety Administration (NHTSA) has previously responded to a similar request for an interpretation of the measurement of seat spacing. I am enclosing a copy of that letter for your information. In that letter, the NHTSA stated that measurement of seat spacing must be made from the seating reference point to the surface of the seat back or restraining barrier, exclusive of portions which protrude from the basic contour of the surface. This interpretation prohibits the measurement of seat spacing from the seating reference point to the side tubing which protrudes from the basic contour of the seat. The NHTSA has received your second letter requesting rulemaking on the issue of seat spacing. That letter is being treated as a petition for rulemaking and will be processed according to agency rulemaking procedures. |
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ID: 1984-2.10OpenTYPE: INTERPRETATION-NHTSA DATE: 06/18/84 FROM: AUTHOR UNAVAILABLE; Frank Berndt; NHTSA TO: John C. Bobak -- President, Crest Industries, Inc. TITLE: FMVSS INTERPRETATION TEXT: John G. Bobak President Crest Industries, Inc. 3841 13th Street Wyandotte, MI 48192 This responds to your letter of May 9, 1984, regarding the application of Federal motor vehicle safety standard No. 212, Windshield retention and standard No. 216, Roof crush resistance to aftermarket windshield adhesives. Your specific question concerned a statement made by Kent Industries that its urethane windshield adhesive "meets and exceeds" those two standards.
You are correct in your understanding that Standards Nos. 212 and 216 only apply to newly manufactured motor vehicles. The standard establish a certain level of performance for those vehicles and do not set specifications for such individual vehicle components as windshield adhesive. In addition, neither of these standards apply to item of motor vehicle equipment, such as windshield adhesive, sold as aftermarket products.
If you have any further questions please let me know. Sincerely Original Signed By Frank Berndt Chief Counsel LETTER FROM JOHN G. BOBAK IS NOT LEGIBLE. |
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ID: nht73-5.50OpenDATE: 12/20/73 FROM: AUTHOR UNAVAILABLE; E. T. Driver; NHTSA TO: Jerry Van Dyke TITLE: FMVSS INTERPRETATION TEXT: This is to confirm the telephone conversation between you and Mr. Douglas Pritchard of my office concerning cruise control devices for mobile homes. As Mr. Pritchard advised you, Motor Vehicle Safety Standard No. 124, Accelerator Control Systems, does not preclude the use of cruise control units. While Standard No. 124 requires that the accelerator control device return to "idle" when the operator removes his foot from the accelerator or when the system itself fails, the term "idle position" is defined in Section 4.1 of the Standard to include the position set by a throttle setting device. As is stated in the Preamble to the Standard: "The rule does not contain requirements for automatic speed control devices. It was found that although nine recall campaigns involving 61,176 vehicles have concerned these devices, no relationship to accelerator overspeed accidents could be established from automatic speed controls. Of the 540 multidisiplinary accident reports that were studied in formulating the final rule, none mentioned the automatic system." I trust this information will be useful to you. |
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ID: nht73-6.8OpenDATE: 04/13/73 FROM: AUTHOR UNAVAILABLE; Robert L. Carter; NHTSA TO: R. W. Lillie & Company TITLE: FMVSS INTERPRETATION TEXT: 99:(ILLEGIBLE TEXT) Director DIVISION OF MOTOR CARRIER SAFETY DEPARTMENT OF TRANSPORTATION 400 SEVENTH STREET, S.W. WASHINGTON, D.C. 20590 ENC. R. W. LILLIE & CO. April 3, 1973 Robert L. Carter United States Department of Transportation National Highway Traffic Safety Administration Dear Mr. Carter: Thank you very much for your letter of March 29, 1973 on Motor Vehicle Safety Standards and the very useful information it included. Even though you said that Standard NO. 116 includes silicone brake fluids, the standard itself on the first page under section S-3 says that it does not apply to petroleum based and silicone based brake fluids. Perhaps you can further enlighten me. Regarding Plastic Fuel Tanks, the proposed rule making notice Docket No. MC-34 - Notice 71-26 must have been followed by some further action. Any ideas on this? Very truly yours, R. W. Lillie |
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ID: nht78-2.41OpenDATE: 03/22/78 FROM: AUTHOR UNAVAILABLE; J. J. Levin, Jr.; NHTSA TO: Industrial Airport TITLE: FMVSS INTERPRETATION TEXT: This responds to your February 16, 1978, request for confirmation that Standard No. 121, Air Brake Systems, does not apply to an air-braked trailer that carries no cargo and consists entirely of a mobile auto-crushing device. Section S3 of Standard No. 121 contains an exclusion for any trailer whose unloaded vehicle weight is not less than 95 percent of its gross vehicle weight rating (GVWR). "Unloaded vehicle weight" means the weight of a vehicle with maximum capacity of all fluids necessary for operation of the vehicle, but without cargo or occupants. Thus, if your mobile auto-crushing trailer carries no cargo or cargo that is less than 5 percent of the vehicles GVWR, it would be excluded from the requirements of Standard No. 121. I would note that Standard No. 108, Lamps, Relective Devices and Associated Equipment, and Standard No. 120, Tire Selection and Rims for Motor Vehicles other than Passenger Cars, may apply to the trailer you describe. I enclose an information sheet that describes where copies of these standards can be obtained. |
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ID: nht87-3.40OpenTYPE: INTERPRETATION-NHTSA DATE: DECEMBER 9, 1987 FROM: ROBERT CUZZI -- BREDA TRANSPORTATION, INC. TO: ERIKA Z. JONES -- CHIEF COUNSEL, NHTSA TITLE: 020-1287 ATTACHMT: MEMO DATED 6-17-88, FROM ERIKA Z. JONES, TO ROBERT CUZZI, STD 301 TEXT: My company, Breda Transportation, Inc., is currently working on a contract for the design, manufacture, and delivery of 236 articulated buses to the city of Seattle. the buses will be designed and manufactured in Italy, with final assembly in the United States. The buses' fuel tank will be built in Italy, and my question regards this. I need to know what federal standards and regulations, if any, refer to the fuel tank. Yesterday, 12/8/87, I spoke to Ms. Deidre Hom of your office, and she informed me that FMV SS 301 applies to fuel tanks, but for vehicles with a GVWR of 10,000 pounds or less. There are, it seems, no applicable FMVSS standards. Could you please confirm this, in writing, or advise me if there are any applicable federal standards which pertain to bus fuel tanks? Your assistance is greatly appreciated. |
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ID: nht94-4.16OpenTYPE: Interpretation-NHTSA DATE: August 31, 1994 FROM: John Womack -- Acting Chief Counsel, NHTSA TO: Guy Dorleans -- Legal Compliance Department, Valeo Vision (France) TITLE: None ATTACHMT: Attached to letter dated 7/15/94 from Guy Dorleans to Office of Chief Council, NHTSA TEXT: We have received your letter of July 15, 1994, asking whether certain front lamp designs would be permissible under Federal Motor Vehicle Safety Standard No. 108. In the basic front lamp design, the upper beam photometrics of Figure 17A would be provided by Lamps A and B. You have asked whether it is possible to add Lamp D, "an auxiliary driving beam." In this variation "all three A, B and D filaments would be p ermanently energized together in high beam mode and table 17a (sic) of FMVSS 108 is then fulfilled." Lamp D meets the photometric requirements of SAE Standard J581 JUN89 Auxiliary Driving Lamps. The photometrics of Figure 17A apply to two-lamp integral beam or combination headlighting systems, and the design in your drawing is that of a four-lamp system, subject to the photometrics of Figure 15A. This configuration is not permissible under Stan dard NO. 108. |
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ID: nht93-2.21OpenDATE: March 19, 1993 FROM: Connie Hafenstine -- Chief, Bureau of Personnel Services, Kansas Department of Transportation; Larry Bluthardt -- Director of Pupil Transportation, Kansas Department of Transportation TO: Patricia Breslin -- Director, Office of Vehicle Safety Standards TITLE: None ATTACHMT: Attached to letter dated 4/22/93 from John Womack to Larry Bluthardt (A41; Std. 124) TEXT: I'm in receipt of a letter from one our Contract Managers concerning the use of built-up foot operated throttle controls. The following questions were asked: 1. Is there any violation of the FMCSR'S in conjunction with the FMVSS concerning the modification of a school bus foot operated throttle control or other equipment modifications that may relate to the physical accommodation of a commercially licensed driver to perform his or her duties behind the wheel? 2. If we can modify the foot operated throttle control to the vehicle (school bus), does the modification require specific registration, certification or inspection prior to the installation? FOR EXAMPLE: Can the modification be made and installed locally, or should the modification be purchased and installed by a certified commercial vendor i.e., manufacturer. Thank you for your assistance. We await your reply. |
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.