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
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ID: nht88-2.45OpenTYPE: INTERPRETATION-NHTSA DATE: 06/08/88 FROM: LACY H. THORNBURG -- ATTORNEY GENERAL; MABEL Y. BULLOCK -- ASSISTANT ATTORNEY GENERAL NORTH CAROLINA TO: SUSAN SCHRUTH -- NATIONAL HIGHWAY AND TRAFFIC SAFETY ADMINISTRATION SAFETY ADMINISTRATION U.S. DEPARTMENT OF TRANSPORTATION TITLE: WINDOW TINTING; FEDERAL PRE-EMPTION OF STATE REGULATIONS ATTACHMT: ATTACHED TO LETTER DATED 04/13/89 FROM ERIKA Z. JONES -- NHTSA TO MABEL Y. BULLOCK, REDBOOK A33, STANDARD 215, VSA 103 (D), VSA SECTION 108 (A)(2)(A); LETTER DATED 12/18/87 FROM LACY H. THORNBURG AND MABEL Y. BULLOCK, SUBJECT MOTOR VEHICLES, RE GULATIONS OF DARK SHADED WINDOWS; PREEMPTION; LETTER DATED 05/06/88 FROM DAIRL BRAGG TO WILLIAM S. HIATT; LETTER DATED 10/28/82 FROM FRANK BERNDT -- NHTSA TO LAWRENCE T. HIROHATA, N0A-30; LETTER DATED 04/04/85 FROM JEFFREY R. MILLER TO ARMOND CARDARELLI; REGULATIONS DATED 07/01/85 EST, FEDERAL AUTO SAFETY LAWS AND MOTOR VEHICLE WINDOW TINTING TEXT: Dear Susan: It has taken a little longer than I anticipated to get this letter to you. I appreciate your taking the time to talk with me on the several occasions that I have called to discuss window tinting with you. I have enclosed a copy of North Carolina's statute regulating window tinting and a copy of the regulations filed pursuant to the statute. I have also enclosed an Attorney General opinion interpreting the statute, recent correspondence from Mr. Daryll Bragg and past correspondence from various NHTSA representatives. My position is that because our statute regulates both owner-operator of motor vehicles with window tinting and manufacturers of such window tinting material, it would be pre-empted by federal regulation if it allows a light transmittance requirement other than 70%. North Carolina General Statute 20-127(f) regulates what type of tinted film the manufacturer is allowed to make available for installation on a motor vehicle in North Carolina. It seems that the wording in 15 USC @ 1391(4) and 15 USC @ 1397 (a)(2)(A) would preempt our state statute if less than 70% light transmittance in window tinting material was permitted -- based on the regulation of the manufacturer, not the operation of the motor vehicle. Please let me know your interpretation of this matter. As I interpret past correspondence from NHTSA, it is your agency's position that the federal regulations do cover after-market tinting on used motor vehicles. If you would like to discuss this m atter further by telephone, please call be at (919) 733-3254. Your assistance in this matter would be greatly appreciated. (North Carolina statute omitted.) Sincerely, ENCLOSURES |
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ID: nht88-2.46OpenTYPE: INTERPRETATION-NHTSA DATE: 06/09/88 FROM: L. F. ROLLIN COMMANDER COMMERCIAL AND TECHNICAL SERVICES SECTION DEPARTMENT OF CALIFORNIA HIGHWAY PATROL TO: JERRY K. YOST -- JERRY'S SERVICE TITLE: NONE ATTACHMT: ATTACHED TO LETTER DATED 08/19/88 TO DOUGLAS H BOSCO, FROM ERIKA Z JONES, REDBOOK A32 (2) STANDARD 108; LETTER DATED 06/16/88, TO ERIKA Z. JONES, FROM DOUGLAS H. BOSCO; LETTER DATED 08/03/87 TO DOUGLAS H. BOSCO FROM ERIKA Z. JONES; LETTER DATED 03/28/88 TO C-MORE-LITE JERRYS SERVICE FROM DON O. HORNING RE TEST REPORT NO 92606; 1988 LETTER TO ERIKA Z. JONES FROM JERRY'S SERVICE TEXT: Dear Mr. Yost: This letter is in response to your inquiry about the legality of the C-More-Light headlight device. My engineering staff reviewed your letter, the letter from NHTSA and the test report (#92606) from Industrial Testing Laboratories (ITL). It is our opinion that the device is legal to install and use on any headlight system designed to meet type "F" pho tometrics. This system is also permitted by California law as long as the photometric output is within the standards established for any other type of headlight. The ITL tests appear to show compliance. Vehicles equipped with the C-More-Light and a control group of similar vehicles without the C-More-Light device should be used in field testing. Responses from drivers should address the effectiveness of the headlights on both high and low beam as well as the reactions of approaching drivers. Reactions such as flashing high beams or other indicators that the headlights are annoying should be noted. Effective testing should ensure that the test and control group vehicles have properly adjusted headlig hts and that the driver's responses are not prejudiced (not informing the drivers which vehicles have operational C-More-Light devices). We look forward to seeing a report on your test results. Any further questions should be directed to my engineering staff. Very truly yours, |
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ID: nht88-2.47OpenTYPE: INTERPRETATION-NHTSA DATE: 06/09/88 FROM: LARRY P. EGLEY TO: LEWIS BUCHANAN -- NHTSA TITLE: NONE ATTACHMT: ATTACHED TO LETTER DATED 08/09/89 FROM STEPHEN P. WOOD -- NHTSA TO LARRY P. EGLEY; REDBOOK A33 [2]; STANDARD 108; LETTER DATED 01/17/89 FROM LARRY P. EGLEY TO KATHLEEN DEMETER -- NHTSA; OCC 3028; LETTER DATED 05/23/89 FROM LARRY P. EGLEY TO KAT HLEEN DEMETER -- NHTSA; LETTER DATED 09/10/88 FROM LARRY P. EGLEY TO KATHLEEN DEMETER -- NHTSA; OCC 2530; REPORT DATED 09/10/88 FROM LARRY P. EGLEY, REQUEST FOR EVALUATION / INTERPRETATION OF PROPOSED INVENTION, SUDDEN STOP FLASHER [SSF]; REPORT DATED 09 /07/88 FROM LARRY P. EGLEY, AN APPEAL FOR VARIANT INTERPRETATION OF NHTSA STANDARDS AS THEY RELATE TO BRAKE LIGHTS AND THE SUDDEN STOP FLASHER [SSF]; LETTER DATED 07/13/88 FROM KATHLEEN DEMETER -- NHTSA TO LARRY P. EGLEY; LETTER DATED 06/23/88 FROM LARRY P. EGLEY TO RALPH HITCHCOCK -- NHTSA; OCC 2256; LETTER DATED 06/20/88 FROM LEWIS S. BUCHANAN -- EPA TO LARRY P. EGLEY; OCC 2199 TEXT: Dear Mr. Buchanan: I have invented a concept which I believe could significantly improve automobile safety. I call this concept the Sudden Stop Flasher (SSF). The SSF would work in conjunction with standard automobile brake lights. During the routine deceleration range, the brake lights would function normally. However, at an unusually high braking deceleration rate, such as when the driver suddenly sees a dog on the road or an accident ahead, the SSF system would utilize a pendulum-type decelerometer in conjunction with a special high-speed flasher to rapidly flash the brake lights automatically (such as drivers sometimes try to do themselves but only whe n they have time!). To increase the effective flash rate, and the "attention-getting index," the high-mount light would flash in rapid sequence with the two lower brake lights, the latter two flashing simualtanously. I believe this concept would be especially effective in preventing high-speed crashes such as on an Interstate highway when separation intervals are greater and when rapid deceleration may be completely unexpected. These crashes too frequently result in ruptured gas tanks and fatalities. The SSF would also be especially applicable, I believe, to sutomobiles with anti-skid brakes, because of their superior braking performance. While anti-skid brakes may be highly effective, ironically, automobiles without anti-skid brakes travelling b ehind them may crash into them because of inferior braking performance. With or without anti-skid braking involved, however, the automatic signal that a high-deceleration slowdown or stop is occuring up ahead could often provide the critical second or two of advance warning which could be the difference between a safe sto p and disaster. Patent application activity is in progress. However, before I invest more money to develop this concept, I want to be reasonably sure it is not likely to be categorically disapproved by NHTSA. While I do not expect approval, of course, based on only a general description, I would very much appreciate your preliminary comments concerning the prospects of this concept, as well as any related advice you may have to offer. Because patent activity is in progress, I would appreciate reasonable confidentially. I would hope to receive a reply from you within 30 days of this date, June 9, 1988. Thank you very much for your attention. |
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ID: nht88-2.48OpenTYPE: INTERPRETATION-NHTSA DATE: 06/10/88 FROM: T. BAILEY -- LEGISLATION ENGINEER, INTERNATIONAL AUTOMOTIVE DESIGN TO: NHTSA TITLE: FMVSS 104 Windshield WIPING & WASHING SYTEMS ATTACHMT: MEMO DATED 11-3-88, TO T.P. BAILEY, FROM ERIKA Z. JONES, STD. 104 TEXT: As an automotive design consultancy we need a clear understanding of this Standard, particularly the requirements of paragraph S4.1.2, Wiped Area. We have a problem with this and would appreciate some advice. Firstly, can you confirm this paragraph is only applicable to passenger cars. Secondly, the hypothetical results for a windscreen are shown on attachment 1. In this, Area A on one side extends to the DLO, on the other, overlaps it. (The DLO is taken to start at the inner edge of the obscuration band). As drawn, the correct perce ntage wiped area is still achieved. Should Area A be wholly:- 1. On exterior surface of glass, inside a perimeter line drawn one inch from edge of daylight opening. 2. On exterior surface of glass, inside the DLO. 3. On exterior surface of glass (ie. whole surface visible from outside vehicle including the obscuration band). 4. On total exterior surface of glass (ie. including the part normally hidden under trim and mouldings). Thank you for your attention. I look forward to hearing from you. See Illumtation on original |
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ID: nht88-2.49OpenTYPE: INTERPRETATION-NHTSA DATE: 06/10/88 FROM: A. J. ACKLEY -- MARTEK CORP. TO: ERICA Z. JONES, CHIEF COUNSEL NHTSA TITLE: NONE ATTACHMT: ATTACHED TO LETTER DATED 12/08/88 FROM ERIKA Z JONES TO A J ACKLEY; REDBOOK A33, STANDARD 125; LETTER DATED 05/26/88 FROM A. J. ACKLEY TO JOAN TILLGHAM, OCC - 2096 TEXT: Dear Ms. Jones: We are in the process of submitting a proposal to an account utilizing the red safety triangle. All of the elements of the device will follow the standards as set by the D.O.C. What we propose is using their logo in the center - see drawing. This woul d revolve (to eliminate a windshield) and add to the reflective quality of the device. Do you see any legal problem with the concept? Thank you. ENCLOSURE |
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ID: nht88-2.5OpenTYPE: INTERPRETATION-NHTSA DATE: 04/21/88 FROM: JUANITA P. DAVISON TO: DEPARTMENT OF TRANSPORTATION VEHICLE CRASH EMERGENCY MANAGEMENT TITLE: NONE ATTACHMT: ATTACHED TO LETTER DATED 03/22/89 FROM ERIKA Z. JONES -- HNTSA TO JUANITA P. DAVISON, REDBOOK A33(2), STANDARD 208 TEXT: Please advise me to whom I can make some input about the automatic type seat belts. I have a 1987 Toyota and have also seen this type seat belt used in Ford makes. Please tell me for what purpose this design has been used. Is it to meet some safety regulation? Or is it some gimmick of the auto manufactuer? This belt is a nuisance and most inconvenient. A person is not fully belted unless the lap belt is also pulled in place. How much simpler to make one move accomplish the process of being fully belted. This shoulder belt takes away the roominess of the front. It is in the way when getting in the car with a handbag or briefcase or package which needs to be placed elsewhere in the car. I wear glasses on a chain and I have to always hold this out of the way when the shoulder belt in in position. Passengers not familiar with the action are startled and confused by it. To disengage the belt after stopping the motor and just sitting in the car, the door has to be opened. This shoulder belt requires a sp ecial unlocking mechanism in case of emergency after impact. What if that is damaged during a collision. It is much more complicated than the push button used to release the lap belt (and combined lap and shoulder belts in other cars). This is a travesty imposed on the ones who were not aware of the inconvenience and the fallacy of "automatic seat belts". I still have to buckle the lap belt and then be ready for the shoulder belt to rivet in place when the motor is turned on. The rev erse process when leaving the car. There is so much lost motion besides all the inconvenience just fr the sake of having a shoulder belt forceably used. Of course all I have to do is take the shoulder belt and lift it back over my head if I don't want to use it while driving. But I do want to be fully belted and would like the one step method. Can I legally disengage the motorized mechanism with the shoulder belt in place so that I can just lift it over my head? This would eliminate some of the dra wbacks. Juanita P. Davison (P.S.) I have also been told it is not safe to wear a shoulder belt without the lap belt, because of possibility of choking! |
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ID: nht88-2.50OpenTYPE: INTERPRETATION-NHTSA DATE: 06/16/88 FROM: DOUGLAS H. BOSCO -- MEMBER OF CONGRESS TO: ERIKA JONES -- NHTSA TITLE: NONE ATTACHMT: ATTACHED TO LETTER DATED 08/19/88 TO DOUGLAS H BOSCO, FROM ERIKA Z JONES, REDBOOK A32 (2) STANDARD 108; LETTER DATED 08/03/87 TO DOUGLAS H. BOSCO FROM ERIKA Z. JONES; LETTER DATED 06/09/88 TO JERRY K YOST FROM L.F ROLLIN; LETTER DATED 03/28/88 TO C-MORE-LITE JERRYS SERVICE FROM DON O. HORNING RE TEST REPORT NO 92606; 1988 LETTER TO ERIKA Z. JONES FROM JERRY'S SERVICE TEXT: Dear Erika: You may recall that I corresponded with you last August regarding a head light device invented by my constituent, Mr. Jerry Yost. Several developments have taken place since that time, which may affect the status of Mr. Yost's C-More-Light invention. Could you please review your earlier letter, the findings of Industrial Testing Laboratories, and the letter from the California Highway Patrol (all enclosed), and let me know what, if any, steps Mr. Yoste needs to take to legally market this device? Thank you very much for your prompt attention to this request. Cordially, |
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ID: nht88-2.51OpenTYPE: INTERPRETATION-NHTSA DATE: 06/17/88 EST FROM: ERIKA Z. JONES -- CHIEF COUNSEL, NHTSA TO: ROBERT CUZZI -- BREDA TRANSPORTATION, INC. TITLE: NONE ATTACHMT: MEMO DATED 12-9-87, FROM ROBERT CUZZI, TO ERIKA Z. JONES, RE: 020-1287 TEXT: This responds to your letter asking whether buses with a gross vehicle weight rating (GVWR) greater than 10,000 pounds are excluded from coverage under Federal Motor Vehicle Safety Standard No. 301, Fuel System Integrity. I regret the delay in respondin g to your letter. The answer to your question is yes. Safety Standard No. 301 applies to new passenger cars, multipurpose passenger vehicles, trucks, and buses having a GVWR of 10,000 pounds or less and to all new school buses. The buses you manufacture for sale as muni cipal transit buses are excluded from Standard No. 301 because their GVWR is greater than the 10,000 pound limit established for the standard. You asked also whether there are any other Federal standards that might apply to the fuel tanks on your transit buses. I have forwarded a copy of your letter to the Federal Highway Administration (FHWA) and the Urban Mass Transit Administration (UMTA) f or their direct reply as to the applicability of any FHWA or UMTA regulations to your transit vehicles. You might also contact the Environmental Protection Agency (EPA) to see whether that agency has any requirements affecting the fuel tanks on your bus es. The general telephone number for the EPA is (202) 382-2090. |
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ID: nht88-2.52OpenTYPE: INTERPRETATION-NHTSA DATE: 06/20/88 FROM: BYUNG M. SOH -- TARGET MARKETING SYSTEMS, INC, MARKETING DIRECTOR TO: OFFICE OF CHIEF COUNSEL, NHTSA TITLE: DOT RULING OR OPINION ATTACHMT: ATTACHED TO LETTER DATED 9-13-88 TO BYUNG M. SOH FROM ERIKAZ. JONES TEXT: Please find in enclosuree photocopies pertaining to informations on two devices which we intend to import to U.S.A. Even though these are not well written, I hope that the copies contain enough informations with which you could give us your opinion whet her these devices require approvals from D.O.T. These are 1. Logical beam: foglight converter 2. C.L.S. system: head-lamp intensity modulator These devices do not require to change existing lighting devices. We believe that these devices enhance road safety. If you require further information, we can be reached at (312)-673-7333 or by fax. (312)-673-7356. Thank you. ENC: 1 one set of photocopies of 'logical beam' and 'C.L.S. Systems' |
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ID: nht88-2.53OpenTYPE: INTERPRETATION-NHTSA DATE: 06/20/88 FROM: LEWIS S. BUCHANAN -- NHTSA DRIVER CONTROL PROGRAMS BRANCH OFFICE OF ALCOHOL & STATE PROGRAMS TRAFFIC SAFETY PROGRAMS TO: LARRY P. EGLEY TITLE: NONE ATTACHMT: ATTACHED TO LETTER DATED 08/09/89 FROM STEPHEN P. WOOD -- NHTSA TO LARRY P. EGLEY; REDBOOK A33 [2]; STANDARD 108; LETTER DATED 01/17/89 FROM LARRY P. EGLEY TO KATHLEEN DEMETER -- NHTSA; OCC 3028; LETTER DATED 05/23/89 FROM LARRY P. EGLEY TO KAT HLEEN DEMETER -- NHTSA; LETTER DATED 09/10/88 FROM LARRY P. EGLEY TO KATHLEEN DEMETER -- NHTSA; OCC 2530; REPORT DATED 09/10/88 FROM LARRY P. EGLEY, REQUEST FOR EVALUATION / INTERPRETATION OF PROPOSED INVENTION SUDDEN STOP FLASHER [SSF]; REPORT DATED 09/ 07/88 FROM LARRY P. EGLEY, AN APPEAL FOR VARIANT INTERPRETATION OF NHTSA STANDARDS AS THEY RELATE TO BRAKE LIGHTS AND THE SUDDEN STOP FLASHER [SSF]; LETTER DATED 07/13/88 FROM KATHLEEN DEMETER -- NHTSA TO LARRY P. EGLEY; LETTER DATED 06/23/88 FROM LARRY P. EGLEY TO RALPH HITCHCOCK -- NHTSA; OCC 2256; LETTER DATED 06/09/88 FROM LARRY P. EGLEY TO LEWIS BUCHANAN TEXT: Dear Mr. Egley: This is in reply to your letter to me regarding your Sudden Stop Flasher. I do not work in the section of the National Highway Traffic Safety Administration which could appropriately respond to your question. Therefore, I have forwarded your letter to Mr. Ralph Hitchcock, Director, Office of Vehicle Safety Standards with a re quest that his office respond to you. I am certain you will be hearing from someone about your inquiry in the near future. Thank you for your interest in preventing motor vehicle crashes. 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.