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 |
|---|---|
ID: nht72-2.48OpenDATE: 02/15/72 FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA TO: Pyroil Company, Inc. TITLE: FMVSS INTERPRETATION TEXT: This is in reply to your letter of February 7 to Lawrence R. Schneider requesting an interpretation of Motor Vehicle Safety Standard No. 116. No standard code numbering system has been established, and composition of the code is at the discretion of the manufacturers and packagers of brake fluid. Note that the use of a code is optional and not a requirement of paragraph S5.2.2.2(b). No standard format has been adopted for the serial number identifying the package lot and date of packaging, and this information may be incorporated into one code, explainable to this agency upon our request. |
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ID: nht71-3.5OpenDATE: 05/20/71 FROM: AUTHOR UNAVAILABLE; R. B. Dyson for L. R. Schneider; NHTSA TO: Boise Cascade Corporation TITLE: FMVSS INTERPRETATION TEXT: This is in reply to your letter of April 29, to Mr. Charles West, on the subject of air brake systems on mobile structure trailers. The standard to which you refer does not require air brakes to be installed on trailers, as your associates seem to fear. However, if your company decides on its own initiative to install air brakes on its mobile structure trailers, such brakes must conform to the air brake standard if the trailer is built on or after the effective date of the standard, January 1, 1973. Please advise us if further clarification is needed. |
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ID: nht71-4.27OpenDATE: 10/22/71 FROM: AUTHOR UNAVAILABLE; L. R. Schneider; NHTSA TO: Utility Trailer Manufacturing Company TITLE: FMVSS INTERPRETATION TEXT: Thank you for your letter of September 22 asking for clarification of the requirement for spacing of rear identification lamps on trailers, as applicable to your "change number 21-23." Until January 1, 1972, Table II of Federal Motor Vehicle Safety Standard No. 108 requires that the three-lamp cluster be mounted "as close as practicable to the vertical center line." However, beginning January 1, 1972, the center lamp of the three-lamp cluster must be mounted on the vertical center line, and the offset arrangement in change number 21-23 will no longer meet the requirements of Standard No. 108. |
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ID: nht71-4.50OpenDATE: 11/17/71 FROM: AUTHOR UNAVAILABLE; J. W. Carson for E. T. Driver; NHTSA TO: Halfpenny, Hahn & Roche TITLE: FMVSS INTERPRETATION TEXT: This is in reply to your letters of October 18, 1971, and November 1, 1971, to Mr. Douglas Toms, Administrator, National Highway Traffic Safety Administration, concerning the "Panic-Stop" signal system from Donel Corporation. You are correct in your interpretation that Federal Motor Vehicle Safety Standard No. 108 is not applicable to the "Panic-Stop" system when this system is not installed on motor vehicles as original equipment. The motor vehicle laws and regulations of the individual States, are, however, applicable to the "Panic-Stop" system when sold and used as aftermarket equipment. |
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ID: nht73-3.31OpenDATE: 02/20/73 FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA TO: Lectron Products, Inc. TITLE: FMVSS INTERPRETATION TEXT: This is in reply to your letter of January 29, 1973, concerning your safety belt interlock system. Paragraph S7.4.1 of Federal Motor Vehicle Safety Standard No. 208, Occupant Crash Protection, requires that the belt system at each occupied seating position be operated after the occupant is seated in order to start the engine. It is our opinion that a system such as yours, which senses whether the safety belt is properly buckled around the occupant before allowing the engine to start, would meet the above requirements and could be used under the option described in S4.1.2.3. |
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ID: nht73-3.9OpenDATE: 01/11/73 FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA TO: Pilot, Inc. TITLE: FMVSS INTERPRETATION TEXT: In your letter of December 15, 1972, to the Department, you ask "Do the regulations require that the brake lite be activated prior to the onset on any brake pressure due to pedal travel can some brake pressure be on before the brake lite lights?" Paragraph S4.5.4 of Motor Vehicle Safety Standard No. 108 Lamps Reflective Devices and Associated Equipment requires that "the stop lamps shall be activated upon application of the service brake." The standard does not state a specific time or brake line pressure at which activation shall occur so that some brake pressure is permitted at the activation point. |
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ID: nht73-4.4OpenDATE: 04/09/73 FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA TO: Mr. Barry Kulik TITLE: FMVSS INTERPRETATION TEXT: This is in response to your letter of March 9, 1973, requesting our confirmation of an opinion given you by phone concerning the method of testing the sensitivity of seat belt warning systems under Motor Vehicle Safety Standard No. 208. We hereby confirm our previous statement that the weight sensing provisions of sections S7.3 and S7.4 do not require the use of a specified test dummy. The sections refer to "persons" of specified weights, thereby implying some distribution of the weight, but they do not reference the test dummy used in other sections of the standard. |
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ID: nht73-5.36OpenDATE: 10/31/73 FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA TO: Motor Coach Industries, Inc. TITLE: FMVSS INTERPRETATION TEXT: This is in reply to your letter of September 5, 1973, to Mr. Schneider asking whether you may furnish side turn signal lamp for inter-city buses at the rear wheels, and if so, the required color. It is correct that there are no Federal safety requirements for side turn signal lamps. Therefore, there is no Federal prohibition against your providing such a lamp, and such restrictions as may exist would be those imposed by the States. Rear mounted turn signal lamps under Federal Standard No. 108 may be either red or amber. |
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ID: nht88-3.52OpenTYPE: INTERPRETATION-NHTSA DATE: 09/14/88 FROM: WENDELL D. KEGG -- TIRE WHEEL CONSULTANTS TO: ERIKA Z. JONES -- CHIEF COUNSEL NHTSA TITLE: NONE ATTACHMT: ATTACHED TO LETTER DATED 01/1/8/89 FROM ERIKA Z. JONES -- NHTSA TO WENDELL D. KEGG, REDBOOK A33, STANDARD 109 TEXT: Dear Ms. Jones: I am confused by the FMVSS 110 Standard. As I read Paragraph S4.3.1 covering inflation pressure on the vehicle placard, the tire cannot by inflated beyond that maximum pressure embossed on the tire. Subparagraph S4.3.1(c) is not clear. Can a vehicle manufacturer specify a higher inflation pressure in a spare tire application than that which is embossed on the sidewall of the tire? Thank you. Very truly yours, |
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ID: nht74-1.11OpenDATE: JANUARY 23, 1974 FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA TO: Correct Manufacturing Corporation TITLE: FMVSS INTERPRETATION TEXT: This is in response to your letter of January 14, 1974, asking about the category into which a Divco truck would fall and the applicability of Motor Vehicle Safety Standards 121 (Air Brake Systems) and 105a (Hydraulic Brake Systems) to them. The vehicles you have described are "trucks" for purposes of the safety standards. The applicability of the braking standards is simple: trucks equipped with air brakes must conform to Standard 121 and those equipped with hydraulic brakes must conform to Standard 105c. I enclose a sheet telling you how to obtain copies of the motor vehicle safety standards and regulations. Enclosure |
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.