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: nht74-3.6OpenDATE: 01/15/74 FROM: W.G. MILBY -- BLUE BIRD BODY COMPANY TO: RICHARD DYSON -- NHTSA ASSISTANT CHIEF COUNSEL TITLE: FMVSS 108 ATTACHMT: ATTACHED TO LETTER DATED 02/19/74 FROM RICHARD DYSON TO W.G. MILBY; N40-30 [ZTV], STANDARD 108; REDBOOK (-) TEXT: We need a ruling on whether it is legal to use rear stop lights on a bus as follows: 1. When brakes are applied rear stop lights are steady burning under all conditions. 2. Place gearshift in reverse - two backup lights are energized and the two seven inch and two four inch rear stop lights flash at a frequency between 60 and 120 cycles per minute. The purpose for such a system is to give school pupils and others additional warning in addition to the backup lights when the bus is in reverse gear and would not interfere with the stop light function. Thanks for an early reply. Yours very truly, |
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ID: nht72-6.60OpenDATE: 11/17/72 FROM: AUTHOR UNAVAILABLE; Robert L. Carter; NHTSA TO: Plaskolite, Inc. TITLE: FMVSS INTERPRETATION TEXT: This is in reply to your letter of June 1, 1971, to Mr. Douglas W. Toms, Acting Administrator, National Highway Traffic Safety Administration, concerning an interpretation relative to the determination of(Illegible Word) of lamps. Both of your interpretations are correct. The location of lamps and reflective devices is determined with the vehicle at its curb weight, which is the weight of a motor vehicle with standard equipment; maximum capacity of engine, fuel, oil, and coolant; and, if so equipped, air conditioning and additional weight optional engine. The overall width is determined with "doors and windows closed" per the interpretation of 32 F.R. 8088, June 21, 1967. The visibility requirements for lamps and reflective devices will therefore be determined with trunk lids, tail gates, hoods, and rear gates in the normal driving, or closed, position. |
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ID: nht73-2.32OpenDATE: 11/06/73 FROM: AUTHOR UNAVAILABLE; W. R. Fiste; NHTSA TO: The Bendix Corporation TITLE: FMVSS INTERPRETATION TEXT: This replies to your letter of October 17, 1973. We have studied the comments contained in your letter carefully, and based on your extensive experience, have no reason to believe that your use of tubing made of solid neoprene rubber for the application in question constitutes a safety hazard. Since there is limited movement involved, the use of "tubing" rather than "hose" is appropriate. The Bureau has not, as yet, established standards other than the general requirements of paragraph 393.43(a) for brake tubing used in applications which do not flex. Use of coiled nylon brake tubing for connections between towed and towing vehicles is permitted if the tubing meets the requirements for Type 3B nylon tubing set forth in SAE Standard J844.c. We appreciate your interest in this safety matter and trust the above is responsive to your inquiry. |
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ID: nht76-1.11OpenDATE: 05/11/76 FROM: AUTHOR UNAVAILABLE; S. P. Wood; NHTSA TO: Gilbert Theissen TITLE: FMVSS INTERPRETATION TEXT: This is in response to your letter of February 5, 1976, to Mrs. Winifred Desmond of this agency concerning braking and rollover characteristics of the Jeep vehicle. We are sorry for the delay in our answer. The Jeep Corporation is correct in saying that 49 CFR 571.105-75, Hydraulic Brake Systems, applies only to passenger cars. It will also apply to school buses manufactured after October 25, 1976. Part 575, Consumer Information Regulations, applies as a whole to all motor vehicles (49 CFR 575.4), but the consumer information item requiring reports on brake performance is limited to passenger cars and motorcycles (49 CFR @ 571.101). With regard to rollover resistance, the agency has issued an advance notice of proposed rulemaking to collect information on rollover resistance, but no requirement to report on rollover performance exists at this time. |
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ID: nht75-1.5OpenDATE: 04/22/75 FROM: AUTHOR UNAVAILABLE; J. C. Schultz; NHTSA TO: Kazuhiko Aoki TITLE: FMVSS INTERPRETATION TEXT: APR 22 1975 N40-30 TWH) Mr. Kazuhiko Aoki 2-3 Nihonbashi Koami-cho 1-chome Chuo-ku/ Toykyo, Japan 103 Dear Mr. Aoki: This responds to your January 30, 1975, question whether the test procedure of S7.7.1 in Standard No. 105-75, Hydraulic brake systems, refers to the parking brake in the next to the last sentence which states that it "may be necessary to reapply it if the vehicle moves slightly" (emphasis added). The word "it" refers to the service brake system, and not the parking brake system. This sentence permits application of the service brake only, which has the effect of taking up parking brake system slack due to rotation of the brake shoes and drum prior to bottoming against the anchor pin. Sincerely, James C. Schultz Chief Counsel |
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ID: nht75-2.8OpenDATE: 09/19/75 FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA TO: Ben Perchik TITLE: FMVSS INTERPRETATION TEXT: This is in response to your letter of July 29, 1975, concerning tire identification markings, received by this agency on August 29, 1975. I have attached two diagrams that illustrate the meaning of the tire code markings on new and retreaded tires. Immediately following "DOT" is a two- or three-letter code (marked in red on the diagrams) that indicates the manufacturer or retreader of the tire. I have also attached a list of the tire manufacturers and retreaders using each code. Following the manufacturer's code are two numbers representing the tire size (marked in blue on the diagrams). Next, some tires will have three letters or numbers which represent an optional tire type code mainly of use to the manufacturer (marked in yellow on the diagrams). The last three numbers represent the date of manufacture (marked in green on the diagrams). I hope this information proves useful to you. |
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ID: nht74-5.30OpenDATE: 04/03/74 FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA TO: MAZDA TITLE: FMVSS INTERPRETATION TEXT: This is in reply to your letter of February 8, 1974, which requests a review of your new accelerator system to determine compliance with Standard No. 124, "Accelerator Control Systems." The NHTSA does not provide a technical review of a manufacturer's product nor certify that a particular design meets the requirements of a standard. That is the manufacturer's responsibility. We will interpret or clarify the meaning of the standard in response to specific questions. We understand your question to be whether two springs surrounding a spring guide and separated by a washer meet the stipulation in S5.1 of Standard No. 124 for ". . . at least two sources of energy . . ." This arrangement of springs would be considered "two sources of energy" within the meaning of the standard. As you requested, the technical description has been held confidential as a "trade secret" and we are returning it to you herewith. ENC. |
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ID: nht91-4.46OpenDATE: July 11, 1991 FROM: Jack Garbo -- President/General Counsel, AVM Products, Inc. TO: Mary Versailles -- NHTSA TITLE: None ATTACHMT: Attached to letter dated 8-14-91 from Paul Jackson Rice to Jack Garbo (A38; Std. 208) TEXT: Per our recent telephone conversation, I am writing to get clarification on the issue of whether the three-point seatbelt is required in all middle and rear outboard seating positions in the multipurpose vehicles after September 1, 1991. My understanding is that the revised FMVSS 208 pertains only to forward facing chairs and sofas, and specifically excludes rearward facing furniture. My company manufactures a small sofa which is mounted on a quick release track system. This sofa faces rearward and is equipped with two lap seatbelts. Please let me know if I am interpreting the language of the regulation properly. Thank you very much for assistance in helping us with this question. |
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ID: nht95-6.4OpenTYPE: INTERPRETATION-NHTSA DATE: August 8, 1995 FROM: Bryan Couch -- Systems Zone Leader, Motor Coach Industries TO: Office of Chief Council, NHTSA TITLE: NONE ATTACHMT: ATTACHED TO 08/28/95 LETTER FROM JOHN WOMACK TO BRYAN COUCH (REDBOOK 2; STD. 108) TEXT: Dear Chief Council: Please find enclosed preliminary drawing showing our proposed location for the front marker lamp and supplementary front marker lamp. We are requesting that you please critique this drawing and respond with your approval, or concerns. The lamp identified as the front marker lamp will meet all FMVSS photometry requirements, and in our opinion is placed as far forward as practicable on this vehicle. The lamp identified as supplementary will not meet the 45 degrees rearward photometry requirement due to the shape of the vehicle. Please accept our advance thank you for your input and we look forward to receiving your response. (Drawing Omitted.) |
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ID: nht95-3.80OpenTYPE: INTERPRETATION-NHTSA DATE: August 8, 1995 FROM: Bryan Couch -- Systems Zone Leader, Motor Coach Industries TO: Office of Chief Council, NHTSA TITLE: NONE ATTACHMT: ATTACHED TO 08/28/95 LETTER FROM JOHN WOMACK TO BRYAN COUCH (REDBOOK 2; STD. 108) TEXT: Dear Chief Council: Please find enclosed preliminary drawing showing our proposed location for the front marker lamp and supplementary front marker lamp. We are requesting that you please critique this drawing and respond with your approval, or concerns. The lamp identified as the front marker lamp will meet all FMVSS photometry requirements, and in our opinion is placed as far forward as practicable on this vehicle. The lamp identified as supplementary will not meet the 45 degrees rearward photometry r equirement due to the shape of the vehicle. Please accept our advance thank you for your input and we look forward to receiving your response. (Drawing Omitted.) |
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.