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: nht74-1.4OpenDATE: 10/03/74 FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA TO: Guy Malleret TITLE: FMVSS INTERPRETATION TEXT: N40-30 (ZTV) OCT 3 1974 Mr. Guy Malleret Director General Officine Alfieri Maserati S.p.A. Modena Italy Dear Mr. Malleret: This is in reply to your letter of September 13, 1974 expressing support for the petition by Citroen for rulemaking to amend Standard No. 105-75. We have responded to Citroen by letter of September 19, 1973 asking for additional technical information and available accident statistics. Since certain models of Maserati vehicles are equipped with the Citroen full power braking system and NHTSA's ultimate decision will affect you. I enclose a copy of our letter with the thought that you may wish to provide us with Maserati's answer to these questions. Yours truly, Richard B. Dyson Acting Chief Counsel Enclosure |
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ID: nht79-4.37OpenDATE: 11/29/79 FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA TO: Mr. B. Stine TITLE: FMVSS INTERPRETATION TEXT: Bennie Stine 1602 Emil Street Madison, Wisconsin 53713 Dear Mr. Stine: This responds to your letter asking whether you may remove the electronic antilock device from your vehicle. You state that the vehicle is unsafe with the antilock device in operation. The National Highway Traffic Safety Administration believes that a properly maintained antilock device can increase the safety of heavy duty vehicles. Accordingly, the agency encourages you to make sure that the antilock device on your vehicle is in the proper working order. However, if you want to remove the device, it is perfectly legal to do so. We suggest that you take the vehicle to its manufacturer or a representative of the manufacturer to be sure that the device is correctly removed and that the remaining braking system is properly adjusted. Sincerely, Frank Berndt Chief Counsel |
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ID: nht78-2.38OpenDATE: 09/21/78 FROM: AUTHOR UNAVAILALE; J. J. Levin, Jr.; NHTSA TO: The B. F. Goodrich Company TITLE: FMVSS INTERPRETATION TEXT: This responds to B. F. Goodrich's August 2, 1978, question whether the specified temperature for brake burnish in S6.1.8.1 of Standard No. 121, Air Brake Systems, should be maintained by reducing maximum vehicle speed during snubs even if the reduced maximum speed does not appear among the snub conditions listed in Table IV of S6.1.8.1. The answer to your question is yes. The snub conditions listed in Table IV represented the agency's best estimate of appropriate speeds for obtaining the specified burnish temperature, given the state-of-the-art of brake technology when the standard was issued. If you have under development a brake design that achieves the specified burnish temperature at a lower speed, it would be correct to reduce vehicle speed below the 40-mph level specified in Table IV to achieve and maintain that temperature. |
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ID: nht78-2.43OpenDATE: 04/13/78 FROM: AUTHOR UNAVAILABLE; J. J. Levin, Jr.; NHTSA TO: E. A. Santiago TITLE: FMVSS INTERPRETATION TEXT: This responds to Raycor Industries' March 13, 1978, question whether Standard No. 121, Air Brake Systems, applies to an air dryer that is installed in the air brake system of trucks that must comply with the standard. The answer to your question is no. Paragraph S3 (Applicability) of Standard No. 121 states that the standard applies to trucks, buses, and trailers equipped with air brake systems (with some specified exceptions). The standard therefore applies only to vehicles, and does not apply to motor vehicle equipment such as the Raycor air dryer unit. The vehicles in question must, of course, conform to Standard No. 121 following installation of the device, if the installation occurs prior to the first purchase in good faith for purposes other than resale. A copy of Standard No. 121 is enclosed for your information. |
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ID: nht78-3.28OpenDATE: 03/22/78 FROM: AUTHOR UNAVAILABLE; J. J. Levin, Jr.; NHTSA TO: Midland Machinery Company, Inc. TITLE: FMVSS INTERPRETATION TEXT: This responds to Midland Machinery Company's February 20, 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 portable mixing plant. 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 maximun capacity of all fluids necessary for operation of the vehicle, but without cargo or occupants. You state that the portable mixing plant trailer carries no cargo, and it would thus be excluded from the requirements of Standard No. 121. Enclosed are copies of Standard No. 108 and 120, along with an information sheet that explains how copies of these and other NHTSA regulations may be obtained. |
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ID: nht93-8.1OpenDATE: November 8, 1993 FROM: Herman Myburgh -- Executive Vice-President, Allvan Corporation TO: John Womack -- NHTSA TITLE: Re: FMVSS Part 571.108 on conspicuity striping on truck ATTACHMT: Attached to letter dated 11/22/93 from John Womack to Herman Myburgh (A41; Std. 108) TEXT: We are manufacturers of curtainsided trailers where the curtain material wraps around the side rails of the trailer. Currently there are no retroreflective tape manufacturer who makes a tape that can stick to or can be RF. welded to the curtain material itself. Could we attach the conspicuity striping to the trailer frame rail itself in such a manner that it will still comply with the latest amendment of "anywhere from 375mm to 1525mm above the ground"? This will be in the same manner as it will probably be applied to container chassis. Your response to this at your earliest convenience will be appreciated. |
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ID: nht76-3.4OpenDATE: 03/11/76 FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA TO: Inertia Switch, Ltd. TITLE: FMVSS INTERPRETATION TEXT: I am writing in response to your March 9, 1976, telephone conversation with Mark Schwimmer of this office concerning the meaning of "GVWR" as it appears in Federal Motor Vehicle Safety Standard No. 301-75, Fuel System Integrity. "GVWR" or "Gross vehicle weight rating" is defined in 49 CFR 571.3 as: the value specified by the manufacturer as the loaded weight of a single vehicle. One constraint on this specification is found in @ 567.4(g)(3) of 49 CFR Part 567, Certification, which requires that the GVWR shall not be less than the sum of the unloaded vehicle weight, rated cargo load, and 150 pounds times the vehicle's designated seating capacity. . . . An information sheet entitled "Where to Obtain Federal Motor Vehicle Safety Standards and Regulations" is enclosed for your convenience. If you have any further questions, please do not hesitate to write. |
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ID: nht76-4.10OpenDATE: 02/06/76 FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA TO: Davidge Warfield TITLE: FMVSS INTERPRETATION TEXT: This is in response to your January 21, 1976, request for an interpretation of Federal Motor Vehicle Safety Standard No. 117, Retreaded Pneumatic Tires. You asked whether a retreaded tire may be manufactured with a casing from which the original manufacturer's tire identification number (required by 49 CFR Part 574 and Standard No. 109) has been buffed off, provided the original DOT symbol remains. The answer to your question is yes. The only items of information that are required to be retained from the original casing are the following: (a) the symbol DOT; (b) the size of the tire; and (c) the actual number of plies or ply rating. A retreaded tire must also, of course, be labeled with the DOT-R symbol and with the retreader's tire identification number, pursuant S6.1 of Standard No. 117 and 49 CFR Part 574. |
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ID: nht74-3.42OpenDATE: 05/14/74 FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA TO: Dave's Tire & Fuel Oil Corp. TITLE: FMVSS INTERPRETATION TEXT: This is in reply to your letters of March 21 and April 22, 1974, in which you ask whether a tire sold as a "blemish" must be guaranteed for workmanship, material, and road hazards. There are no Federal requirements that manufacturers guarantee blemish (or non-blemish) tires. Such guarantees are within the discretion of each manufacturer. However, Federal Motor Vehicle Safety Standard No. 109 (49 CFR @ 571.109) requires all new passenger car tires to meet minimum safety performance levels for high speed performance, endurance, strength, bead unseating, physical dimensions and tradewear indicators. These requirements apply similarly to both blemish and non-blemish tires. We have enclosed for your information a copy of the Federal Trade Commission's Tire Advertising and Labeling Guides which contain in Guide 11 requirements for the labeling of blemish tires. ENC. |
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ID: nht74-3.48OpenDATE: 05/31/74 FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA TO: Mitsubishi Motors Corporation TITLE: FMVSS INTERPRETATION TEXT: This responds to your verbal request to Mr. Herlihy of this office for a determination that a 3-point, continuous loop, Type II seat belt assembly would meet the requirements of @ 4.1.2.3.1(a) of Standard No. 208 if its emergency-locking retractor were mounted at the outboard floor anchorage instead of at the roof rail. The belt is routed from the fixed upper torso end, through a slip-fitting latch and pelvic section, to the retractor. Assuming the belt assembly meets any other adjustment requirement of @ 4.1.2.3.1, it would conform to @7.1 or standard No. 208 and @4.1(g) of Standard No. 209 with the emergency-looking retractor mounted at the outboard floor anchorage. The upper torso restraint would "adjust by means of an emergency-locking retractor" within the meaning of @7.1 as long as the continuous loop permitted slack from the floor-mounted emergencylocking retractor to reach the upper torso portion of the assembly. |
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.