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: 77-2.6OpenTYPE: INTERPRETATION-NHTSA DATE: 04/08/77 FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA TO: Wayne Corporation TITLE: FMVSS INTERPRETATION TEXT: This responds to your February 22, 1977, letter asking whether a restraining barrier in front of a seat with a back higher than that required in S5.1.2 of Standard No. 222, School Bus Passenger Seating and Crash Protection, must coincide with or lie outside of the perimeter of the extended seat back. The requirements for restraining barrier surface area are found in paragraph S5.2.2 of the standard. That section states that: "in a front projected view of the bus, each point of the barrier's perimeter coincides with or lies outside of the perimeter of the seat back of the seat for which it is required." The seat back of the seat for which a restraining barrier is required has dimensions specified in S5.1.2 of the standard. Therefore, a restraining barrier must only coincide with or lie outside of the seat back surface required by S5.1.2. If a seat back surface exceeds the size required in Standard No. 222, the size of the restraining barrier need not coincide. SINCERELY, Wayne Corporation February 22, 1977 Frank R. Berndt Office of Chief Counsel NHTSA This inquiry is in reference to FMVSS 222, School Bus Passenger Seating and Crash Protection, as applied to school buses with a GVWR of more than 10,000 pounds. Must the perimeter of a barrier located in front of a seat having a back higher than that required by Section S5.1.2 coincide with or lie outside of the perimeter of the extended seat back? Your prompt attention to this matter and an early reply will be greatly appreciated. Robert B. Kurre Director of Engineering |
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ID: nht74-1.19OpenDATE: 09/23/74 FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA TO: Dexter Axle Company, Inc. TITLE: FMVSS INTERPRETATION TEXT: This responds to your August 19, 1974, request to be advised of the steps necessary to acquire a manufacturer code number as required by Standards No. 119, New pneumatic tires for vehicles other than passenger cars, and No. 120, Tire selection and rims for motor vehicles other than passenger cars. Standard No. 119 applies to tires-only and it is the responsibility of the tire manufacturer to obtain a code number and label it on his products. As a user of tires, you do not have obligations under this standard. Standard No. 120 is a proposal which applies to rim construction and the selection of the correct rim for the (Illegible Word) equips. As a manufacturer of rims you would have a responsibility to label your products if this proposal becomes an effective regulation. However, we noted in the preamble to that proposal (copy enclosed) that we will not require manufacturer codes until a separate manufacturer code system has been established. I am also enclosing a copy of the most recent proposal on manufacturer codes. Yours truly, ATTACH August 19, 1974 Docket Section NHTSA Re: FMVSS 119 and 120 Dear Sir: Dexter Axle Co. Inc. is a manufacturer of running gear equipment for Mobile Homes and Recreational Vehicles. In our product line are wheels and rims subject to standards 119 and 120. Please advise on the steps we must take to obtain a manufacturers code number as required. Thank you. Very truly yours, DEXTER AXLE COMPANY, INC.; J. A. Brown -- Manager - Engineering Res. & Dev. |
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ID: nht74-1.40OpenDATE: 02/19/74 FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA TO: Blue Bird Body Company TITLE: FMVSS INTERPRETATION TEXT: This is in reply to your letter of January 15, 1974, asking whether a school bus rear lighting system is permissible that activates the back-up lamps and flashes four red stop lamps when the gearshift is in reverse. The system of supplemental school bus warning lamps you describe is one that is not specified by Standard No. 108. Although S4.6(b) states that "All . . . lamps [other than those specified in S4.6(a)] shall be steady burning . . . ," we interpret this requirement as covering only the systems specified by the standard. Therefore there is no Federal prohibition against your installation of such a system. However, the system would be subject to regulation by the individual States, some of which may have restrictions on the use of flashing lights. Yours truly, ATTACH. January 15, 1974 Richard Dyson -- Assistant Chief Counsel, U. S. Dept. of Transportation, NHTSA Dear Mr. Dyson: SUBJECT: FMVSS 1C8 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, BLUE BIRD BODY COMPANY; W. G. Milby -- Project Engineer |
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ID: nht78-2.5OpenDATE: 11/28/78 FROM: AUTHOR UNAVAILABLE; J. J. Levin, Jr.; NHTSA TO: Blue Bird Body Company TITLE: FMVSS INTERPRETATION TEXT: NOV 28 1978 NOA-30 Mr. W. G. Milby Manager, Engineering Service Blue Bird Body Company P.O. Box 937 Fort Valley, Georgia 31030 Dear Mr. Milby: This responds to your August 3, 1978, letter asking how to compute the area of a sample of a body panel when testing for compliance with Standard No. 221, School Bus Body Joint Strength. In your letter, you suggest that the net cross-sectional area of the sample is determined by multiplying the width of the sample by its thickness and then subtracting the area of each discreet fastener hole. The National Highway Traffic Safety Administration agrees that this procedure yields the correct area of the sample, and is the method used by the agency in its compliance testing. Sincerely, Joseph J. Levin, Jr. Chief Counsel August 3, 1978 Mr. Joseph J. Levin Chief Counsel National Highway Traffic Safety Administration Washington, D.C. 20590 Dear Mr. Levin: The purpose of this letter is to seek confirmation of our interpretation regarding FMVSS 221, School Bus Joint Strength. It is our understanding that in meeting the requirements of S5, that the area to be used for calculating purposes, when discreet fasteners are used, is the net area of the weakest joined body panel. We define the net area as the width of the sample multiplied by its thickness, less the projected area of each discreet fastener hole. We look forward to receiving an early written confirmation of this interpretation. Thank you. Very truly yours, W. G. Milby Manager, Engineering Services sw |
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ID: nht78-4.27OpenDATE: 03/10/78 FROM: JAMES TYDINGS, -- THOMAS BUILT BUSES, SPECIFICATIONS ENGINEER TO: ROGER TILTON -- U. S. DEPARTMENT OF TRANSPORTATION TITLE: FMVSS #217 - SECTION 5.2, "PROVISION OF EMERGENCY EXITS". ATTACHMT: ATTACHED TO LETTER DATED 02/03/88 FROM ERIKA Z JONES TO L.T. MITCHELL; REDBOOK A31, VSA 102, SEC 571 DEFINITION; STANDARD 208, 222; LETTER DATED 08/21/87 FROM L. T. MITCHELL TO ERIKA Z. JONES RE REQUEST FOR INTERPRETATION ON FMVSS 222 ON SCHOOL BUSES WITH GVWR OF 10,000 POUNDS OR LESS; OCC-945; LETTER DATED 05/11/78 FROM JOSEPH J. LEVIN TO JAMES TYDINGS TEXT: Dear Mr. Tilton; Confirming our phone conversation of March 10, 1978, regarding the above Standard and Section. Our question revolved around the number of openings (Push-Out Windows) for a bus with wide seats (39" width) for adults. The case we cited was that the 39" seat would be used by only two adults per seat. This was for comfort reasons. Yet in reading the definition of a "Designated Seating Position" where it speaks to "at least as large as a fifth percentile adult female", the seat could provide for three females of the above size or smaller. Our contention was that our intent and that of the user was that the seat would be occupied by only two adults, and we would base our calculations upon that number to establish the number of exits. It was further discussed that there would be no intent on our part tothe safety provisions of the standard. We also suggested that we would label the vehicle seating capacity on insidevehicle in plain sight. To this you agreed, stating that it would be Trusting this is an accurate record of conversation, we shall look forward to concurrence in this matter. |
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ID: nht78-4.8OpenDATE: 11/29/78 FROM: AUTHOR UNAVAILABLE; J. J. Levin, Jr.; NHTSA TO: Chrysler Corporation TITLE: FMVSS INTERPRETATION TEXT: FMVSS INTERPRETATION Ms. Joan Claybrook Administrator National Highway Traffic Safety Administration 400 Seventh Street, SW Washington, D.C. 20590 RE: MVSS 101 - Controls and Displays Docket 1-18; Notice 13 By notice published in the Federal Register on June 26, 1978 (43 FR 27541) the NHTSA amended MVSS 101 - Controls and Displays to require the use of ISO symbols on specific controls, telltales and gauges and the use of specified word call-outs to identify certain other controls and displays. The amendment is effective September 1, 1980 and until that date vehicles may comply with either the current or the amended standard. As amended the standard specifies symbols for separate oil pressure and coolant temperature gauges or telltales. It has been industry practice on some models to combine the monitroing of these two functions into a single telltale to indicate an "engine" malfunction. We believe that combining these two functions is appropriate because the response by the driver to either of these engine malfunctions is the same, safely pull to the side of the road and turn off the engine. We see nothing in the standard to prohibit the continued use of an engine function telltale. Therefore, Chrysler Corporation interprets the requirements of the standard to mean that a telltale which monitors engine function may be identified by the word "Engine". Therefore, we request the Administrator's concurrence with our interpretation that a telltale which monitors both engine oil pressure and coolant temperature may use the identifying word "Engine". If, however, our interpretation is not correct, this letter should be considered as a petition for reconsideration requesting that S5.2.3 and Table 2 be amended to allow the use of the word "Engine" to identify a telltale which monitors both engine oil pressure and coolant temperature. Sincerely, |
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ID: nht79-1.48OpenDATE: 04/09/79 FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA TO: Subaru of America, Inc. TITLE: FMVSS INTERPRETATION TEXT: This is in response to your letter of March 26, 1979, requesting our interpretation of whether the turn signal identification symbol which you propose meets the requirements of Federal Motor Vehicle Safety Standard No. 101-80, Controls and Displays. The answer is yes. As long as the turn signal symbol is displayed in the horizontal mode, as shown in Table 1, it will comply with the standard. Small additional arrows that will not be confused with the turn signal symbol may be incorporated to indicate movement of the control. Your thin vertical arrows do not appear to pose any possibility of causing such confusion. Sincerely, ATTACH. SABARU OF AMERICA, Inc. March 26, 1979 Our Ref. No. 039-79C Office of Chief Counsel -- National Highway Traffic Safety Administration, U.S. Dept. of Transportation Gentlemen: We request your approval of our interpretation of FMVSS 101-80, Controls and Displays, as it applies to turn signal switch identification. For 1980 model year Subaru proposes to place identifying arrows in the horizontal mode. We also propose to have small arrows in the vertical axis to denote the direction of movement necessary to activate the turn signal switch. From the enclosed sketch you will note that the horizontal arrows are the predominant ones. Due to production lead time problems, response at your earliest convenience will be greatly appreciated. Sincerely, Paul Utans -- Associate Vice President, Product Compliance Enc. cc: Fuji Heavy Industries, Ltd.; Fuji Liaison Office (Graphics omitted) |
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ID: nht91-7.48OpenDATE: December 16, 1991 FROM: William R. Willen -- Managing Counsel, Product Legal Group, American Honda Motor Co., Inc. TO: Paul Jackson Rice -- Chief Counsel, NHTSA TITLE: None ATTACHMT: Attached to letter dated 1/28/92 from Paul Jackson Rice (Stephen P. Wood) to William R. Willen, Esq. (A39; Std. 123) TEXT: I am writing to you seeking an interpretation. FMVSS 123, in section 5.2.1. contains the following language: "if a motorcycle is equipped with a self proportioning, or an antilock braking device utilizing a single control for both front and rear brakes, the control shall be located and operable in the same manner as a rear brake control." Honda is in the final stages of developing an advanced version of their proportional braking system for motorcycles. It offers: a) Full proportioning front and rear when utilizing either the front hand control, or the rear foot control. In order to fully comply with the "letter" of the standard, this system would seem to be out of compliance when the front hand brake is applied. Honda feels that it is an obvious safety advantage to offer the full extent of proportioning, with "any" brake application! Honda also feels that the authors of 123 did not foresee the possibility of proportioning, being available with the application of the right, front handlebar lever. Since the "full spirit" of FMVSS 123 is being met, Honda is seeking an interpretation of this system that would permit the use of these advancements. Telephone conversations have taken place between Doug Toms, an advisor on the project, and Steve Wood. Honda stands ready to answer any questions, or provide additional technical detail should that be desired. Honda will be conducting sales "decision meetings" on Jan. 22, and 23, 1992. It would be most helpful if some "feeling" for your response could be gained by telephone just prior to those dates. |
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ID: nht89-3.32OpenTYPE: INTERPRETATION-NHTSA DATE: 11/06/89 FROM: STEPHEN P. WOOD -- NHTSA ACTING CHIEF COUNSEL TO: S. WATANABE -- MANAGER AUTOMOTIVE LIGHTING ENGINEERING CONTROL DEPT. STANLEY ELECTRIC CO., LTD., JAPAN TITLE: NONE TEXT: Dear Mr. Watanabe: This is in reply to your FAX of September 14, 1989, asking for an interpretation of Motor Vehicle Safety Standard No. 108, with respect to a vehicle headlamp aiming device (VHAD), as shown in the drawing attached to your letter. You have two questions: "1) Does a VHAD without a function which compensates the deviation of floor slope satisfy FMVSS No. 108 S7.7.5.2(a)(1)(v)?" Paragraph S7.7.5.2(a)(v) states that "Means shall be provided in the VHAD for compensating for deviations in floor slope not less than 1.2 degrees from the horizontal that would affect the correct positioning of the headlamp for vertical aim." If a VHAD is "without a function which compensates the deviation of floor slope" it would not satisfy Standard No. 108. "2) This Head Lamp is designed to be aimed vertically by means of observing only one spirit level placed on the movable reflector, as shown in the drawing. Does this structure of VHAD satisfy FMVSS No. 108 S7.7.5.2(a)(1)(v)?" The answer is yes, if observation of the simple spirit level is coordinated with an off-vehicle measurement of floor slope. As located, the spirit level with the range of +/- 1.2 degree range will allow aim of the headlamp, even though the vehicle may n ot be level, and will compensate for floor slopes of up to 1.2 degrees, thus fulfilling the requirement that there be compensatory means when the vehicle upon which the headlamp is mounted is not resting upon level ground. I hope that this answers your questions. Sincerely, [DIAGRAM OF VEHICLE HEADLAMP AIMING DEVICE OMITTED] |
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ID: nht90-1.13OpenTYPE: INTERPRETATION-NHTSA DATE: 01/09/90 FROM: STEPHEN P. WOOD -- NHTSA ACTING CHIEF COUNSEL TO: JAMES A. COWAN, DIRECTOR OF ENGINEERING CROWN COACH INCORPORATED TITLE: NONE ATTACHMT: LETTER DATED 11/24/89 FROM JAMES A. COWAN -- CROWN COACH INC TO ERIKA JONES -- NHTSA; RE FMVSS 217, BUS WINDOW RETENTION AND RELEASE; OCC 2847; LETTER DATED 11/29/88 FROM JAMES A. COWAN -- CROWN COACH INC; RE FMVSS 217, BUS WINDOW RETENTION AND RELEASE TEXT: Dear Mr. Cowan: This is in response to your request for an interpretation of Federal Motor Vehicle Safety Standard No. 217: Bus Window Retention and Release. I apologize for the delay in responding to your inquiry. Your letter explained that Crown plans to sell one prototype school bus model which was developed but not produced, and which contains a side emergency exit which is wider than required under Standard No. 217. Because of the wider door, the seatback of the passenger seat located immediately forward of the emergency exit door intrudes into the emergency door exit opening. You have requested an interpretation as to whether this is consistent with Standard No. 217. The answer to your question is no. Standard No. 217 specifically requires that "[a] vertical transverse plane tangent to the rearmost point of a seatback shall pass through the forward edge of a side emergency door." S5.4.2.1(b). This requirement prohibits the forward seat or seatback fr om extending into the door opening regardless of the size of the door opening. Therefore, as it is now configured, the bus you have described in your letter is not in compliance with Standard No. 217. I hope you have found this information helpful. Please contact David Greenburg of this office at (202) 366-2992 if you have any further questions concerning this issue. Sincerely, |
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.