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: nht72-1.34OpenDATE: 03/29/72 FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA TO: Toyo Kogyo Detroit Office TITLE: FMVSS INTERPRETATION TEXT: This is in response to your letter of March 16, 1972, in which you ask whether the definition of "unloaded vehicle weight" is the same as that for "'curb weight' plus optional parts," and whether the definition of "gross vehicle weight" is the same as that for "maximum loaded vehicle weight." The two sets of definitions are expressed in substantially different terms. The new terms, "unloaded vehicle weight" and "gross vehicle weight rating" are more general than the older ones. The newer terms also eliminate some ambiguities in the definitions based on "curb weight," such as just what is (Illegible Word) by "standard equipment," and whether other vehicle fluids besides fuel, oil, and coolant should be included. Further, GVWR is a rating, not necessarily identical to any scale weight although some constraints have been placed on it in our Certification regulations (@ 567.4(g)(3)). Thus, although the two sets of definitions are somewhat similar in their application, they are different enough that each must be interpreted and used in its own terms. |
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ID: nht72-1.36OpenDATE: 09/05/72 FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA TO: Toyo Kogyo Co., Ltd. TITLE: FMVSS INTERPRETATION TEXT: This is in reply to your letter of August 8, 1972, on the subject of the location of the anchorages for passive belt systems. We understand from your letter that you are considering using a door-mounted anchorage for your system, but we are uncertain as to the nature of your difficulties with Standard No. 210. The standard does not prohibit door-mounted anchorages. If an anchorage can be placed on the door so that it directs the belt across the occupant at the angle specified in the standard, and if it also meets the strength requirements, then it would be considered to conform to the standard. It may be that the anchorage you are considering fails to provide the correct belt angle. At this time there is no exemption provided for passive belts from the belt angle requirements of Standard No. 210. If you wish to petition for rulemaking to amend the requirements for passive belts, you should accompany your petition with full information concerning the system and the advantages of the proposed anchorage locations |
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ID: nht72-1.46OpenDATE: 06/12/72 FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA TO: The Peterson Company TITLE: FMVSS INTERPRETATION TEXT: This is in reply to your letter of May 24, 1972, inquiring whether Standard No. 213 requires head rests, arm rests, and shields of certain Peterson child seats to be covered with nonrecovery, or slow-recovery energy absorbing material. Paragraph S4.10.3 of Standard No. 213 exempts the contactable area of a rigid side of a child seating system from the requirement that it be covered with deformable, nonrecovery, or slow-recovery energy absorbing material (S4.10.1 and S4.10.2), when the contactable area of the side that is higher than the system's seating surface is at least 24 square inches. We would consider head rests, arm rests, and shields of the Peterson child seats in question to be within the exemption of S4.10.3 if their contactable area above the child seating surface is 24 square inches or more. I point out, however, that the proposal of September 23, 1970 (35 F.R. 14786) would alter this result, as the exemption would no longer extend to any components contactable by the head. |
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ID: nht72-1.48OpenDATE: 03/10/72 FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA TO: Irvin Industries Inc. TITLE: FMVSS INTERPRETATION TEXT: This is in reply to your letter of February 23, 1972, in which you list information you wish to label on child seats you will manufacture, and ask whether the information as presented will comply with Motor Vehicle Safety Standard No. 213. You state that a label containing the model number, date of manufacture, and the company's name and place of business will be permanently affixed to the product, while a separate legend, containing other information, will be molded on the bottom of the seat in raised letters at least 3/32 inches high. The labeling scheme you wish to use would conform to paragraph S4.1 ("Labeling") of Standard No. 213, providing, of course, the blank spaces for model number and date of manufacture are appropriately filled in. We would suggest, however, that that part of the molded legend beginning" . . . and there is a minimum of 19 inches vertical clearance between this seating . . .", to the end of that provision be simplified to be more understandable to an ordinary consumer. WE ARE PLEASED TO BE OF ASSISTANCE. |
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ID: nht72-2.17OpenDATE: 11/21/72 FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA TO: American Plywood Association TITLE: FMVSS INTERPRETATION TEXT: This is in response to your letter of October 25, 1972, in which you ask whether there are any NHTSA requirements applicable to "do-it-yourself" plans for camper trailers. Certain Federal requirements are applicable to the camper trailers which will be built based on your plans. These are Federal Motor Vehicle Safety Standard No. 108. "Lamps, Reflective Devices, and Associated Equipment" (49 CFR 571.108). Requirements which we expect to issue in the near future will apply to the tires with which such trailers are equipped (proposed Standards Nos. 119 and 120). Moreover, manufacturers of these trailers are required by NHTSA "certification" regulations (49 CFR Part 567) to certify the trailer's confermity with the motor vehicle safety standards. These requirements apply to the finished trailer itself, and not to the plans for it, but the plans should include stops that will cause the finished trailer to conferm to all applicable requirements. I have enclosed directions on how you may obtain copies of NHTSA requirements. |
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ID: nht72-3.1OpenDATE: 01/25/72 FROM: AUTHOR UNAVAILABLE; E. T. Driver; NHTSA TO: North Carolina Tire Dealers Retreaders Association, Inc. TITLE: FMVSS INTERPRETATION TEXT: Thank you for sending a copy of your December 1971 issue "Tarheel Tire Topics". In a note attached to these topics you asked Dr. E. H. Wallace to clarify whether a tubeless tire casing can be changed to a tube-type retread by identifying it as such during the process. There is no prohibition of this practice mentioned in Standard No. 117 relating to retreaded tires. (Illegible Words) the rule is clear concerning the necessity for maintaining the highest quality in selection of materials and processings during the retreaded process. We would be interested in an explanation of the circumstances where it appears necessary to change a tubeless casing to a tubed tire. The circumstances which we visualize leading to this change seem to us to lead to rejection of the casing for any retread purposes. We also would like to point out that, although not strictly prohibited, the manufacturer who changes a tubeless casing to a tubed tire is liable for penalties if the resulting tire will not perform on compliance tests. |
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ID: nht72-3.10OpenDATE: 09/07/72 FROM: AUTHOR UNAVAILABLE; Robert L. Carter; NHTSA TO: Kennedy, Holland, DeLacy and Svoboda, Attorneys at Law TITLE: FMVSS INTERPRETATION TEXT: Your letter dated July 27, 1972, to the Department of Commerce, regarding information pertaining to the National Traffic and Motor Vehicle Safety Act of 1966, initial standards, was referred to this office for reply. The National Traffic and Motor Vehicle Safety Act of 1966, in establishing the legislative basin for the Federal Motor Vehicle Safety Standards, required that the initial standards, to the maximum extent possible, be based on existing safety standards. An Advance Notice of Proposed Rule Making, soliciting suggestions, opinions, and proposals for consideration in promulgating the initial standards, was published in the Federal Register on October 8, 1966. Paragraph S3.3(d) of the initial Motor Vehicle Safety Standard No. 201 was based on Paragraph S3.2.5 of Federal Standard No. 515/3a, which was published in the Federal Register on July 15, 1966, (31 F.R. 9628), after consideration of the comments received in response to the Advance Notice. I have enclosed a copy of Standard No. 515/3a. Thank you for your letter. Your interest in automotive safety is appreciated. |
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ID: nht71-3.2OpenDATE: 05/14/71 FROM: AUTHOR UNAVAILABLE; C. A. Baker for E. T. Driver; NHTSA TO: J. A. Kackney & Sons, Inc. TITLE: FMVSS INTERPRETATION TEXT: This is in reply to your letter of May 3, 1971, to Mr. Julian E. Leycath of this Administration, concerning the installation of supplementary stop and rear turn signal lamps on your van type delivery bodies. Installation of the supplementary stop and rear turn signal lamps, in the manner described in your letter and as shown on your drawings 69C-81, and 69C-41 (enclosed with your letter). would not impair the effectiveness of lamps, reflective devices, and associated equipment required by Federal Motor Vehicle Safety Standard No. 108 and would not be prohibited by that standard. Standard No. 108 presently specified that the required stop lamps be mounted at a height "not less than 15 inches nor more than 72 inches". No mounting heights are presently specified for the required rear turn signal lamps. Effective January 1, 1972, the mounting height of required rear turn signal lamps will be "not less than 15 inches nor more than 83 inches". These limitations on mounting heights for the required lamps are not applicable to supplementary stop and rear turn signal lamps. |
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ID: nht71-4.35OpenDATE: 10/29/71 FROM: AUTHOR UNAVAILABLE; R. L. Carter; NHTSA TO: Joseph Lucas (Electrical), Ltd. TITLE: FMVSS INTERPRETATION TEXT: This is in reply to the petition of Joseph Lucas (Electrical) Ltd. dated October 13, 1971, for rulemaking to amend Federal Motor Vehicle Safety Standard No. 108, Lamps, Reflective Devices, and Associated Equipment. Specifically, you have asked for an amendment of paragraph S4.1.2 either to reduce the(Illegible Word) test cycle of the warpage test for backup and stop lamps from 10 minutes to 5 minutes, or to conduct the test for these lamps using a continuously flashing filament. Petitions for reconsideration of the 10 minute heat test cycle were filed following amendment of Standard No. 108 on October 31, 1970 (35 F.R. 16840). These petitions were denied on February 3, 1971 (36 F.R. 1896), because the Traffic Safety Administration had determined that the 10-minute cycle is appropriate in view of the frequency of usage of stop and backup lamps. I enclose a copy of the denial. The Administrator has determined that your petition contains no new information such as to merit rulemaking on this issue, and we must therefore respectfully deny your petition. |
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ID: nht71-4.4OpenDATE: 08/16/71 FROM: AUTHOR UNAVAILABLE; L. R. Schneider; NHTSA TO: Truck Equipment & Body Distributor Association TITLE: FMVSS INTERPRETATION TEXT: This is in reply to your letter of July 28 requesting a clarification of paragraph S4.3.1.1 of Standard No. 108. This paragraph requires the installation of auxiliary lighting equipment, if the required lighting equipment is prevented from conforming to photometric output and visibility values by motor vehicle equipment such as snow plows, street sweepers, etc. You ask, in essence, whether auxiliary lamps must be provided in two situations: when the motor vehicle equipment is sold with but not attached to the vehicle, and when no equipment is sold with the vehicle but the vehicle is equipped with a hoist upon which equipment may be mounted. With respect to the first situation, compliance should be determined with the equipment attached which(Illegible Word) the vehicle at the time it is sold. As for the second situation, compliance of a vehicle which is equipped at time of sale with hoists or mounting brackes only, and for which equipment will be provided at a time subsequent to sale, should be determined with the vehicle in its as-sold condition. |
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.