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: nht74-4.25OpenDATE: 05/30/74 FROM: AUTHOR UNAVAILABLE; E. T. Driver; NHTSA TO: The Philadelphia Inquirer TITLE: FMVSS INTERPRETATION TEXT: This is in reply to your recent letter to the U.S. Department of Transportation concerning Federal regulations on supplemental lights to be installed on your trucks. There are no requirements in our Federal Motor Vehicle Safety Standards which would prohibit the use of a white light on the cab roof to Illuminate information on the front of the truck body. Likewise, we have no specifications for such lights. The use and location of the lights would, however, be subject to regulations imposed by the individual States. As a matter of information, the front identification lamps and clearance lamps, as shown on the sketch attached to your letter, do not appear to be located in accordance with the requirements of Federal Motor Vehicle Safety Standard No. 108 (copy enclosed). Table II requires these lamps to be located as close as practicable to the top of the vehicle. In your unscaled drawing the top of the truck body appears significantly higher than the cab. Thank you for your interest in highway safety. ENC. N.H.T.S.A We are acquiring a new fleet and we would like to mount a white light on the roof of our cabs that would illuminate the Company Name and vehicle identification number which is located on the front of the truck body. Before installing these lights, we would like to know if there is any part of the D.O.T. regulations which would prohibit their use, or if there are any regulations regarding their location, type, etc. Thank you for your cooperation. Patrick R. Mulrooney Fleet Safety MGR. The Philadelphia Inquirer ENC. (Graphics omitted) |
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ID: nht74-5.24OpenDATE: 04/10/74 FROM: AUTHOR UNAVAILABLE; Lawrence R. Schneider; NHTSA TO: Mr. Jesse R. Hollins COPYEE: T. W. HERLIHY TITLE: FMVSS INTERPRETATION TEXT: This responds to your March 23, 1974 request for an explanation of why Docket 69-7; Notice 26 was sent to you in response to your February 15, 1974, telegram request for the reasons or needs for such a (alternative interlock) proposal or amendment." The Notice 26 preamble states in the fourth paragraph appearing on page 9831 of Volume 38 of the Federal Register the "reasons or needs" for proposing an alternative interlock system: that "it may prove desirable for some manufacturers". The proposal would allow greater freedom in the design of a belt interlock system while preserving the direct use incentive of the present sequential ignition interlock system. The Automotive Need conclusion to which you refer, that one effect of the alternative interlock would be to permit operation of the vehicle in reverse, was not a reason cited or relied on by the National Highway Traffic Safety Administration in making the proposal. I hope I have made clear why Notice 26 was sent to you. I have enclosed Notice 31 for your information. March 23, 1974 Lawrence R. Schneider, Esq. Chief Counsel National Highway Traffic Safety Administration Dear Sir: Re: N40-30 (TWH) I acknowledge the receipt of a copy of Docket 69-7; Notice 26 which was enclosed with your letter as per above reference number. My telegram of February 14th. 1974 to the attention of Robert L. Carter, Assistant Administrator of NHTSA asked for certain information specifically pertaining to Docket 69-7; Notice 31. I am at a loss to understand your reason for submitting Notice 26 to me. Can you explain this? Thanking you, I am Very truly yours JESSE R. HOLLINS |
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ID: nht73-4.27OpenDATE: 06/14/73 FROM: AUTOR UNAVAILABLE; Lawrence R. Schneider; NHTSA TO: Hayden; Smith; Ford & Hays TITLE: FMVSR INTERPRETATION TEXT: This is in reply to your letter of May 21, 1973, forwarding to us your second attempt to compose a letter that will conform to Part 577, Defect Notification, for a defect involving the lighting in boat trailers manufactured by V/M Custom Boat Trailers. We responded to an earlier letter from you on May 16, 1973. Section 577.6 prohibits the making of any statement in the notification that either states or implies that the problem discussed is not a defect, or that it does not relate to motor vehicle safety. As we indicated to you in our letter of May 16, we considered your statement, "The defect on those trailers . . . does not affect the mechanical operation of said trailer except insofar as the lighting is inefficient as installed according to the U.S. Department of Transportation" to be prohibited by section 577.6. The additional phrase, "This statement is one of fact only and is not intended to be a disclaimer which is prohibited by section 577.6 of the Act", which you have now inserted, does not remedy that deficiency. The regulation states that such a statement may not be made at all; it does not allow it to be made and denied. Our objection to the statement is with your description of the defect as an "inefficiency" according to the Department of Transportation. This safety related defect results, rather, from violations of law which require your client's products to meet minimim safe levels of performance. We recommend that rather than attempt once again to rewrite your statement, and risk violation of the regulation, you delete it entirely, and send the notification to purchasers forthwith. In other respects your notification appears to conform to Part 577. |
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ID: nht75-4.4OpenDATE: 05/28/75 FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA TO: Dairy Equipment Co. TITLE: FMVSS INTERPRETATION TEXT: This responds to Dairy Equipment's April 3, 1975 request for a discussion of what constitutes the manufacture of a trailer in cases where used components from an existing vehicle are involved. In response to a similar request from the Truck Trailer Manufacturers Association, the National Highway Traffic Safety Administration recently prepared a comprehensive discussion of this subject, a copy of which is enclosed for your information. YOURS TRULY, April 3, 1975 David E. Wells, Chief Counsel Federal Highway Administration Department of Transportation Confirming the phone conversation on March 31, 1975 between Mr. Kazmierazack of the D.O.T. and Mr. Ehinger of our company regarding the rebuilding of used trailers, Mr. Kazmierzack stated that we can obtain an official ruling by writing to your office. We have customers who want to replace the tank of an existing semi-trailer tank motor vehicle utilizing the under carriage frame, suspension, axles, wheels, and tires from the old semi-trailer. Can you confirm to us in writing Mr. Kazmierzack's verbal approval to Mr. Ehinger that this type of repair does not incur any obligation to comply with current motor vehicle safety standards? We intend to retain the vehicle identification number, make, and model year. Thank you for your consideration. DAIRY EQUIPMENT COMPANY Jim Koester Product Engineer |
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ID: 1985-01.48OpenTYPE: INTERPRETATION-NHTSA DATE: 03/14/85 EST FROM: BARRY FELRICE -- NHTSA RULEMAKING TO: FRED W. BOWDITCH -- MVMA TECHNICAL AFFAIRS DIVISION TITLE: NONE ATTACHMT: LETTER DATED 10/29/84 FROM FRED W. BOWDITCH -- MVMA TO DIANE K. STEED -- NHTSA, PETITION TEXT: Dear Mr. Bowditch: On October 29, 1984, the Motor Vehicle Manufacturers Association filed a petition for rulemaking to amend Motor Vehicle Safety Standard No. 108, Lamps, Reflective Devices, and Associated Equipment. The petition requested "removal from section 4.1.1.36(a) (2) of the limitation requiring the three aiming pads to be located on the exterior face of the headlamp lens." You have suggested the mounting flange at the lens-reflector joint as an acceptable alternative location for the aiming pads. The language suggested in the petition for amendment of S4.1.1.36(a) (2) would also allow all three legs to be adjustable on the headlamp aimers. The agency has proposed amendments to Standard No. 108 (49 FR 47880) to delete the final sentence of paragraph S4.1.1.36(a) (2) with reference to aiming locating plates, and to delete Figures 9-1 and 9-2. Thus, this aspect of your petition has already been granted. We have filed your petition as a comment in the docket to be considered in future rulemaking action on this subject. Further, we interpret the words "The exterior face of each...lens" in paragraph S4.1.1.36(a) (2) to mean all portions of the lens face including the mounting flange which is a molded and indivisible part of the lens. Thus, no rulemaking is considered necessary to implement this item of your petition. Your request also included a suggestion that the minimum height of the lettering for the adjustment of the legs on the aimer adapter should be reduced from 0.25 inch to 4 mm. This is being addressed in pending rulemaking. Therefore, no further action is necessary at this time. Sincerely, |
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ID: nht76-1.47OpenDATE: 11/17/76 FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA TO: Department of California Highway Patrol TITLE: FMVSS INTERPRETATION TEXT: This responds to your September 16, 1976, question whether any Federal regulation requires that the maximum load rating assigned to a passenger car tire be reduced by approximately 10 percent in calculating its maximum load rating for use on a multipurpose passenger vehicle (MPV), truck, or bus. The answer to your question is yes. Standard No. 120, Tire Selection and Rims for Motor Vehicles Other than Passenger Cars, became effective September 1, 1976, and provides for the reduced maximum load rating you describe. Section S5.1.2 of the standard provides in part that "[when] a tire listed in [the passenger car tire standard] is installed on a multipurpose passenger vehicle, truck, bus, or trailer, the tire's load rating shall be reduced by dividing by 1.10 before calculating the sum [that must at least equal the axle system's gross axle weight rating]." A copy of the standard, with subsequent amendments, is enclosed for your information. SINCERELY, DEPARTMENT OF CALIFORNIA HIGHWAY PATROL September 16, 1976 John W. Snow National Highway Traffic Safety Administration We have noted that page XI of the 1976 Tire and Rim Association standards, copy enclosed, requires that a passenger car tire be loaded to not more than 91 percent of its rated load when used on a truck, bus or multipurpose passenger vehicle. Is this limitation included as a part of Federal Motor Vehicle Safety Standards Nos. 109 or 119? If the requirement is applicable, we propose to include it in our Vehicle Equipment Inspection Guide. If the restriction is not referenced in the standard, are we preempted from adopting it as a part of the enclosed State regulations on tires? WARREN M. HEATH Commander Engineering Section |
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ID: 2784yOpen Mr. Takahiro Maeda Dear Mr. Maeda: This is in reply to your letter of September 28, l990, requesting an interpretation of Motor Vehicle Safety Standard No. l08. Table IV of the standard establishes a minimum "edge to edge separation distance" between turn signal lamps and tail or stop lamps installed on motorcycles. You have asked whether the edge in question is the outer edge of the lamp assembly itself, or the edge of the reflector in the lamp. The minimum edge to edge separation distance is measured from the edge of the illuminated surface of one lamp to another, that is to say, from the edge of the effective projected luminous area of one lens to the edge of the effective projected luminous area of the other. It is unclear from the drawing you enclosed of the "tail/brake lamp" whether the edge of its effective projected luminous area of the lens is at the edge of the reflector, or at the edge of the lamp (as appears to be the case with the "turn signal"). If the former, the distance is measured between the edge of the tail/stop lamp reflector to the edge of the turn signal lamp assembly as you have initially indicated. Sincerely,
Paul Jackson Rice Chief Counsel ref:l08 d:l2/7/90 |
1990 |
ID: lieberman.ztvOpenEdward Lieberman, P.E. Dear Mr. Lieberman: This is in reply to your letter of February 11, 2003, containing a proposal to conduct a field evaluation of a supplementary motor vehicle lighting system. This system is called the "Sunlight Safety System" and was developed by Harold Caine. You have requested "a variance of FMVSS 108." The National Highway Traffic Safety Administration (NHTSA) has authority to exempt a vehicle only from complying with one or more of the Federal motor vehicle safety standards at the time it is manufactured. When a vehicle has been sold and is in use on the public roads, it becomes subject to applicable State laws, and, if it is a commercial vehicle used in interstate commerce, the regulations of the Federal Motor Carrier Safety Administration. You should consult these authorities to determine whether use of this supplemental lighting system is legal on state and interstate highways. NHTSA has had occasion over the years to comment on Mr. Caines lighting systems. I enclose a copy of our letter of November 16, 1999, to Mr. Terry Wagar of the Department of Motor Vehicles, State of New York, which represents the agencys most recent views on the subject. If you have any questions, you may call Taylor Vinson of this Office (202-366-5263). Sincerely, Jacqueline Glassman Enclosure cc: FMCSA |
2003 |
ID: nht88-2.99OpenTYPE: INTERPRETATION-NHTSA DATE: 08/11/88 FROM: ERIKA Z. JONES -- CHIEF COUNSEL NHTSA TO: J. MIKE CALLAHAN -- PRECISION IMAGES TITLE: NONE ATTACHMT: LETTER DATED 04/14/87 TO TAYLOR VINSON FROM J MIKE CALLAHAN; OCC-409; LETTER DATED 11/19/87 TO ROGER M. COX FROM ERIKA Z JONES, STANDARD 108; LETTER DATED 09/03/87 TO DAVID M. ROMANSKY, FROM ERIKA Z JONES TEXT: Dear Mr. Callahan: This is in reply to your letter of April 14, 1987, to Mr. Vinson of this office with respect to your representation of a company "that will be selling plastic name plates which would be installed behind the red-lens of the third brake light." You stated that "these are to be sold to new car dealerships. When the driver of the car steps on the brake the dealer's name lights up." You ask for letters regarding the legality of the name plates for 24 States. We regret the delay in responding to your request. When Mr. Vinson tried to reach you by phone this week he was told that you had already received a letter, and that the answer was negative. Perhaps that letter came from one of the 24 States listed in your letter. We are unable to advise you of the legality under State laws, but I have enclosed representative interpretation letters of this agency on the legality of similar devices under Federal law. ENCLOSURE Sincerely, |
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ID: 21572A.ztvOpenMs. Kathleen H. Wolf Dear Ms Wolf: We have received the petition for temporary exemption from Federal Motor Vehicle Safety Standard No. 123 for the Vespa ET4 (125 and 150cc) motor scooter that you have submitted on behalf of its manufacturer, Piaggio & C. S.p.A. of Pontedera, Italy. Ordinarily, petitions are filed by manufacturers and not their agents. However, we understand that our laws and language may not be familiar to companies located in countries where English is not the primary tongue, and we are willing to accommodate them when it is feasible. The petition you submitted must be accompanied by a statement signed by an official of Piaggio authorizing you to file the petition and attesting that the signer has read the petition and affirms that the information and arguments contained in it are true and accurate. If you will obtain a statement containing these elements and file it with us, we shall be pleased to consider the matter further. The petition meets our procedural requirements, and we require no further information. We shall begin to prepare a notice for publication in the Federal Register when we have received the statement, and you may expect a decision three to four months after that. If you have any questions, you may call Taylor Vinson of this Office (202-366-5263). Sincerely, |
2000 |
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.