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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search results table | |
ID: nht93-7.7OpenDATE: October 1, 1993 Est. FROM: Bob Carver TITLE: None ATTACHMT: Attached to letter dated 11/22/93 from John Womack to Bob Carver (A41; Part 571; Std. 217) TEXT: I'm an engineer at Wayne Wheeled Vehicles, a commercial and school bus manufacturing company. My job here is to see ensure compliance to FMVSS 217, effective May 1994. I have a question for you in which I need an official ruling concerning FMVSS 217 S5.5.3(c): Each opening for a required emergency exit shall be outlined around its outside perimeter with a minimum 3 centimeters wide retroreflective tape, either red, white, or yellow in color, that when tested under the conditions specified in S6.1 of 571.131 meets the criteria specified in Table 1. If an emergency roof exit is required, is it necessary to outline it with the retroreflective tape even though it is not visible unless the bus is tilted on its side? Also, Charles Hott at NHTSA said that the width requirement will be revised to 1 inch. Can you confirm this? Thanks in advance for your prompt consideration and assistance concerning this matter. |
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ID: nht94-1.16OpenTYPE: Interpretation-NHTSA DATE: January 10, 1994 FROM: Adam A. Freund -- Manager, Testing Services, Standards Testing Laboratories, Inc. TO: Walter Myers -- Office of Chief Counsel, NHTSA TITLE: Table II Minimum Static; Breaking Energy (inch pounds) D.O.T. 119 ATTACHMT: Attached to letter dated 4/12/94 from John Womack to Adam A. Freund (A42; Std. 119) TEXT: Further to our telephone conversation of this date, please find enclosed a copy of subject matter for your perusal. As we had discussed I believe there is a typo in the highlighted columns marked respectively MOTORCYCLE and ALL 12 INCH OR SMALLER RIM SI ZE. If I am correct the first column MOTORCYCLE should show a plunger diameter of 5/16" and the column marked ALL 12 INCH OR SMALLER RIM SIZE should show a plunger diameter of 3/4". I would appreciate your qualifying my interpretation of above subject matter. If my interpretation is incorrect, please advise me how the respective columns should be marked. Standards Testing Laboratories, Inc. would greatly appreciate any expedited consideration you may allow us on this request. ATTACHMENT (Table omitted.) |
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ID: nht72-1.33OpenDATE: 06/27/72 FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA TO: Checker Motors Sales Corporation TITLE: FMVSS INTERPRETATION TEXT: This is in reply to your letter of May 25, 1972, asking whether you, as a selling dealer, may install steel-belted radial ply tires on an 8-passenger Checker taxicab. You state that the vehicle is normally delivered to you with tires having the "D" load range. Federal Motor Vehicle Safety Standard No. 110 (49 CFR 571.110, copy enclosed) requires each passenger car to be equipped at the time of sale to a first purchaser with tires of certain minimum load carrying capacity, based on the weight of the vehicle. Any steel-belted radial ply tire that meets these load carrying requirements with respect to your vehicles may be installed by a selling dealer. Radial tires of similar or related sizes, but of different manufacture, however, may have different load ratings. We suggest, therefore, that you contact Checker Motor Corporation for their recommendations as to which radial ply tires may be installed on these vehicles without adversely affecting the vehicle's conformity with Motor Vehicle Safety Standard No. 110. |
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ID: nht75-6.33OpenDATE: 07/10/75 FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA TO: Cooney Equipment Company TITLE: FMVSR INTERPRETATION TEXT: Your letter of June 17, 1969, to Mr. Donald Morrison of the Bureau of Motor Carrier Safety, concerning switching arrangements for running lamps, has been transferred to this Office for consideration and reply. Enclosed for your information is a copy of Federal Motor Vehicle Safety Standard No. 108 on lighting requirements for motor vehicles. This standard is applicable to new vehicles manufactured on or after the effective date of January 1, 1969. Special wiring requirements, such as lamp switching arrangements, are included in paragraphs S3.4 through S3.4.7 of the standard. We do not completely understand your usage of the term "running lights." If you are referring only to tail lamps, your attention is invited specifically to paragraph S3.4.3 of the standard which is quoted as follows: "As a minimum the tail lamps shall be illuminated when the headlamps are illuminated except when the headlamps are being flashed." The switching arrangements for other "running lights," such as clearance lamps and identification lamps, are at the option of the vehicle manufacturer. Thank you for writing. |
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ID: nht76-2.50OpenDATE: 02/09/76 FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA TO: Gillig Brothers School Bus Co. TITLE: FMVSS INTERPRETATION TEXT: This is in response to your request for information concerning methods of ensuring the compliance of school buses with the barrier crash test requirements of Federal Motor Vehicle Safety Standard No. 301-75, Fuel System Integrity. Standard No. 301-75, while establishing minimum performance levels, does not specify any particular design requirements for school bus fuel systems. A manufacturer is free to design his vehicles in the manner that he believes most appropriate to ensure compliance. To this end, you may find helpful information in a study by Dynamic Science entitled School Bus Safety Improvement Program. The NHTSA cannot assure you, however, that following the suggestions contained in the study will guarantee that your school buses will comply with the standard. The study is filed in the NHTSA's public docket as document number 75-03-GR1. Copies may be obtained by writing to: Technical Reference Branch National Highway Traffic Safety Administration Room 5108 400 Seventh Street, S.W. Washington, D.C. 20590 You should refer to the following publication numbers: HS 801-615, -616, and -617. |
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ID: nht92-4.48OpenDATE: August 6, 1992 FROM: R.J. Misorski -- Director, Maintenance & Repair, Maersk Inc. TO: Legal Council, NHTSA COPYEE: A. Petrizzo, W. Drozd TITLE: None ATTACHMT: Attached to letter dated 8/21/92 from Paul J. Rice to R.J. Misorski (A39; Std. 108) TEXT: Attached is a copy of the Federal Register outlining your rule change that went into effect December 1, 1991. The new rule now requires a minimum of 12 square inches of lens area for rear stop or turn signals on vehicles over 80" wide, regardless of the separation between lamps. We feel that equipment manufactured prior to December 1991 would be exempt from this ruling. Our interpretation of this new rule is that it only applies to equipment that is manufactured after December 1, 1991. We would highly appreciate if you could confirm our understanding in writing in order that we may ensure compliance with our equipment fleet. Attachment Copy of page 20158 of the 5/15/90 Federal Register pertaining to 49 CFR Part 571, Federal Motor Vehicle Safety Standards; Lamps, Reflective Devices, and Associated Equipment (action: final rule). (Text omitted) |
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ID: nht91-5.51OpenDATE: September 17, 1991 FROM: Jeffrey P. Shimp -- Engineer, Fleet Engineering & Q.A., Transportation Department, Baltimore Gas and Electric TO: Mary Versailles -- NHTSA, Office of Chief Counsel TITLE: None ATTACHMT: Attached to letter dated 10-9-91 from Paul Jackson Rice to Jeffrey P. Shimp (A38; VSA S108(a)(2)(A)) TEXT: In order to better serve our customers, we have found it necessary to increase the size of our work crews from two men to three men in one of our departments. Due to the amount of material required for these crews, we have typically utilized (two passenger) cargo vans for this operation. In view of the above, we would like to install a third seat in our cargo vans (mini and/or short wheel base), which are delivered by the manufacturers as a certified completed vehicle. We would greatly appreciate it if you could provide a written response advising us on this issue so that we can be in compliance with the Federal Motor Vehicle Safety Standards and any other governing regulations. If I can be of any assistance to you, please feel free to contact me (301/281-3630).
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ID: nht90-1.99OpenTYPE: Interpretation-NHTSA DATE: April 5, 1990 FROM: Richard E. Portors -- Vice President and General Manager, Royale Limousine Manufacturers TO: Zachary R. Fraser -- NHTSA TITLE: None ATTACHMT: Attached to letter dated 8-30-90 from P.J. Rice to R.E. Portors (A36; Std. 108) TEXT: Please give me an advisory on my understanding of requirement 571.108 - S4.1.1.41 high mounted stop lamps section (a) projected area of not less than 4 1/2 square inches. The 90 Cadillac stop lamps measure 6 sq. inches of area. When installing a boomerang TV antenna the shaft area displaces 1.125 sq. inch of area, this would leave an exposed area of 4 7/8" of light and would exceed the minimum requirements of section (a) . Also, section (b) would not be affected by the boomerang. Without window glazing, section (c) would not be affected either. I feel the boomerang antenna positioned properly would not affect the requirements of 571.108. Please advise me on your findings as soon as possible. Attached is a copy of the Federal Register, section 571.108, 49 CFR Ch. V (10-1-85- Edition), page 218 (text omitted) |
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ID: nht94-2.49OpenTYPE: INTERPRETATION-NHTSA DATE: April 19, 1994 FROM: S. Greiff -- PARS, Passive Ruckhaltesysteme GmbH TO: Chief Counsel -- US Department of Transportation, NHTSA TITLE: None ATTACHMT: Attached To Letter Dated 6/8/94 From John Womack To S. Greiff (A42; Std. 208) TEXT: Per Fax: 001/202-366-3820 Your "Laboratory Test Procedure For FMVSS 208/212/219/301" Gentleman: PARS is a company developing occupant restraint systems for the world wide automotive industry. One of our major topics is the development of airbag systems. For development and validation of the restraint systems we own a Barrier Impact Test Facility which was built up in 1993 new. Our runway is 80 m (260 feet's) long. The velocity tolerance up to 60 kph is +/- 0.1 kph. In your Laboratory Test Procedure for FMVSS testing, a minimum runway length of 500 feet is requested. We would like to ask you for an interpretation of your "500 feet requirement". It would be much appreciated, if we could get an answer by fax. Our fax no. is: 01149/6023/942-133 Thank you very much for your efforts in advance. Sincerely yours |
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ID: nht94-4.53OpenTYPE: INTERPRETATION-NHTSA DATE: October 14, 1994 FROM: Randal Busick -- President, Vehicle Science Corporation TO: Mary Versailles, Esq. -- Office of the Chief Counsel, NHTSA TITLE: Re: Request for interpretation of FMVSS 208 S7.1.2 ATTACHMT: Attached to 1/5/95 letter from Philip R. Recht to Randal Busick (A43; Std. 208; Std. 210) TEXT: Dear Ms Versailles: This is to request a clarification of FMVSS 208 S7.1.2. More specifically, would a seat belt system as shown on the attached drawing be in compliance with S7.1.2 as a so-called "semi-integrated" seat belt? As shown on the drawing, the inboard lower FMVSS 210 anchorage, n1 is located on the seat frame and thus, as the seat moves fore and aft, the system allows a minimum of two seat belt adjustment positions and the distance between the two extreme adjustmen t positions of the system is more than 5 cm. n1 The belt which holds the buckle is attached to this inboard anchorage. We look forward to your response. If you have any questions, kindly contact the undersigned. Sincerely Enclosure (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.