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: aiam3376OpenMr. James E. Skeen, President, Cragar Industries, Inc., 19007 South Reyes Avenue, Compton, California 90221; Mr. James E. Skeen President Cragar Industries Inc. 19007 South Reyes Avenue Compton California 90221; Dear Mr. Skeen: The Office of Vehicle Safety compliance has asked me to respond to you October 14, 1980, letter asking for a clarification of the basis upon which it was suggested that your wheel spinners may not be in compliance with Safety Standard No. 211, *Wheel Nuts, Wheel Discs, and Hub Caps*.; Standard No. 211 prohibits the manufacture or assembly of wheel nuts wheel disc and hub caps that incorporate winged projections. This safety standard has been in effect since 1968 and was implemented at that time, because it was determined that these devices presented potential safety hazard to pedestrians and to cyclists. Prior to 1968, manufacturers were constructing devices with winged projections that extended quite far from the wheel. To prevent this from arising again, the agency issued the standard prohibiting the manufacture of *all* such devices.; From reviewing the wheel spinner that you are producing, our technica staff has concluded that it incorporates a winged projection of the type prohibited by the standard. Accordingly, our staff notified you of your possible noncompliance. I trust that this clarifies the basis of our investigation. Any questions that you have with respect to this possible noncompliance would be referred to our office of Vehicle Safety Compliance.; Pursuant to your request, the National Highway Traffic Safet Administration will provide confidential treatment, subject to the limitation of 15 U.S.C. 1418(a)(2)(B), for the total production figure in paragraph 4 of your October 14 letter; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam3701OpenMr. Alberto Negro, Fiat Research & Development - USA Branch, Fiat Motors of North America, Inc., Parklane Towers West, Suite 1210, Dearborn, MI 48126; Mr. Alberto Negro Fiat Research & Development - USA Branch Fiat Motors of North America Inc. Parklane Towers West Suite 1210 Dearborn MI 48126; Dear Mr. Negro: This is in reply to your letter of May 9, 1983, to Mr. Vinson of m staff with respect to conformance of a planned stop lamp design with Federal Motor Vehicle Safety Standard No. 108, *Lamps, Reflective Devices, and Associated Equipment*.; The design comprises two compartments separated by a reflex reflector One of the compartments will meet the photometric requirements for a stop lamp, in your judgment. The other will not, but in conjunction with the first compartment 'the requirements can be met.' You have asked if this arrangement is acceptable pursuant to paragraph S4.1.1.6 which allows photometric requirements to be met by a combination of compartments or lamps.; Paragraph S4.1.1.6 is intended to cover replacement stop lamps fo vehicles manufactured between January 1, 1973, and September 1, 1978, when the SAE standard for stop lamps incorporated into Standard No. 108 was SAE J586b, September 1966. As such, its requirements are not relevant to your concerns.; However, SAE J586c, August 1970, whose requirements do apply to sto lamps, appears to permit your design. Under paragraph 3.1, where the distance between filament centers of two stop lamps does not exceed 22 inches (presumably your design) the photometric readings of both lamps must be combined to meet the photometric requirements of Table 1 of J586c applicable to two lighted sections. However, the combined candela must not exceed the specified total of 360 for two lighted sections.; I hope this answers your questions. Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam5586OpenGiuseppe Di Vito Societa Italiana Vetro S.p.A. Sede e Stabilimenti 66050 San Salvo (Chieti) Zona Industriale; Giuseppe Di Vito Societa Italiana Vetro S.p.A. Sede e Stabilimenti 66050 San Salvo (Chieti) Zona Industriale; Dear Mr. Di Vito: This responds to your May 22, 1995, letter requestin an interpretation regarding the testing requirements of Federal Motor Vehicle Safety Standard (FMVSS) No. 205, 'Glazing Materials.' I apologize for the delay in responding. You stated in your letter that you have been requested to manufacture for BMW some type 15A side window security glazing with an internal spall shield coating. Because of the adhesive with which it is applied, this coating cannot pass test number 4 of ANSI Z.26.1-1977 (the boil test). Nevertheless, you urge that test number 5 (the bake test) be used as a substitute for purposes of compliance certification. The boil test and the bake test are not equivalent, and your glazing would have to meet the boil test. Although both tests subject the glazing to the same heat for the same period, the bake test applies the heat using an oven, whereas the boil test applies the heat using boiling water. Section 5 of Z.26 explicitly states that the boil test is to be used for safety glass and that the bake test is only to be used for multiple glazed units. The illustrations that you enclosed with your letter show that your glazing is not a multiple glazed unit. Therefore, it has to meet the boil test to be certified for use on motor vehicles sold in this country. I hope this information is helpful. If you have any further questions or need additional information, please feel free to write Paul Atelsek of my staff at this address or call him at (202) 366-2992. Sincerely, John Womack Acting Chief Counsel; |
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ID: aiam2194OpenKenneth R. Arnold, Esq., Secretary and General Counsel, WAGNER ELECTRIC CORPORATION, 100 Misty Lane, Parsippany, NJ, 07054; Kenneth R. Arnold Esq. Secretary and General Counsel WAGNER ELECTRIC CORPORATION 100 Misty Lane Parsippany NJ 07054; Dear Mr. Arnold: This is in reply to your letter of December 11, 1975, referring to ou letter to Ideal Corporation of September 17, 1975. You commented that 'customers believe that the NHTSA approves the unqualified use of variable-load flashers for replacement turn-signal applications.' You have requested 'confirmation that the intent of Standard 108, S4.5.6 is to only permit a variable-load flasher to be used only on an Excepted Vehicle.' Your interpretation is incorrect.; Although the NHTSA does not approve of the use of variable-load tur signal flashers as replacement for fixed-load flashers, the choice of replacement equipment for a vehicle in use is that of the consumer, and is not subject to Federal control. We have no authority to require that the owner of a vehicle originally equipped with a fixed load flasher replace it with a fixed load flasher. This may be the reason for your confusion with respect to the NHTSA's reaction to Ideal Corporation's petition for rulemaking. It was not necessary to amend the standard as requested by Ideal, since it already allowed the type of replacement suggested, and this agency generally does not regulate modifications by consumers. Such an amendment would have been superfluous.; As indicated in our letter to Ideal, we continue to believe i preferable that consumers be informed that a variable load flasher will not provide an outage indication. To this end the NHTSA is considering rulemaking that would require labeling on containers of variable-load flashers.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam3835OpenMr. Walter A. Genthe, President, Hella North America, Inc., P.O. Box 499, Flora, IL 62839; Mr. Walter A. Genthe President Hella North America Inc. P.O. Box 499 Flora IL 62839; Dear Mr. Genthe: This is in reply to your letter of January 23, 1984, with respect t the inclusion of other lighting functions in a replaceable bulb headlamp compartment. These functions could include parking lamps, turn signal lamps, or side marker lamps. The bulb used would meet Standard No. 108/SAE specifications for the function chosen and they would be incorporated into the compartment by a 'sealed attachment.' You represent that there will be no impairment of any function, and that the overall assembly will meet all photometric and environmental specifications. You have asked whether such a combination assembly is permissible under Standard No. 108.; The agency interprets Standard No. 108's specifications for replaceabl bulb headlamps as allowing only one bulb in a lamp assembly to be used for headlighting purposes. It is silent as to whether additional bulbs may be used to provide other lighting functions. This means that such a bulb is permitted.; Obviously the inclusion of a second bulb can affect the characteristic of the assembly, whether through heat build up, the introduction of contaminants through the junction of the bulb and assembly, etc. These problems would appear to be minimized under the assumptions set forth in your letter. We believe therefore that, under these conditions, an auxiliary bulb could be included in the headlighting compartment, provided that the assembly meets all applicable requirements of Standard No. 108 for each function. Problems that may develop in service would be subject to the safety related defects authority of the National Traffic and Motor Vehicle Safety Act.; If Hella proceeds with a multi-bulb design, we would like to reques that it share with us the types of tests it will be developing which it deems necessary to insure adequate safety performance, so that our knowledge of the art lamp technology may be broadened.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam3729OpenMr. C. B. Bright, Jr., C. B. Bright Motor Co., Route 1, Ashland, MS 38603; Mr. C. B. Bright Jr. C. B. Bright Motor Co. Route 1 Ashland MS 38603; Dear Mr. Bright: This is in reply to your letter of July 19, 1983, to Mr. Vinson of thi office. You have asked whether you are violating any Federal standards or regulations by adding 'right side steering, accelerator, brakes & turn signal controls to rural mail carriers delivery vehicles (cars, pickup, jeeps, etc.).' You have told us that you do not modify in any way the left hand side controls with which the vehicle was originally equipped.; Assuming that your modifications do not affect the performance of an of the systems with which the vehicle was equipped by its original manufacturer, your conversion operations would not be prohibited by the National Traffic and Motor Vehicle Safety Act. However, with respect to any new vehicle that you modify which has not yet reached its first purchaser for purposes other than resale, you are required to affix a label identifying you as the alterer and certifying that the vehicle as altered meets all applicable Federal motor vehicle safety standards. This is required by Title 49 Code of Federal Regulations, Section 567.7. I enclose a copy of Part 567 for your information.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam3549OpenMr. E. M. Ryan, American Transportation Corporation, Highway 65 South, Conway, AR 72032; Mr. E. M. Ryan American Transportation Corporation Highway 65 South Conway AR 72032; Dear Mr. Ryan: This responds to your February 27, 1982, letter asking whether vehicle which transports 10 or fewer persons could be classified as a bus if it is built with a traditional bus body. The vehicle transports fewer persons than normal, because it is designed for wheelchair occupants. The answer to your question is no.; The classification of a vehicle as a bus or a multipurpose passenge vehicle for the purposes of the Federal motor vehicle safety standards depends upon its passenger capacity. See the definitions of 'bus' and 'multipurpose passenger vehicle' in 49 CFR 571.3. A vehicle that transports the number of persons that you mentioned in your letter must be classified as a multipurpose passenger vehicle. The fact that the vehicle is designed as a bus has no relevance to its classification. The controlling factor is passenger capacity.; Since the vehicle would be a multipurpose passenger vehicle, it woul be required to comply with all of the standards applicable to those vehicles. This would include compliance with Standard No. 206, *Door Locks and Door Retention Components*.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam3730OpenMr. C. B. Bright, Jr., C. B. Bright Motor Co., Route 1, Ashland, MS 38603; Mr. C. B. Bright Jr. C. B. Bright Motor Co. Route 1 Ashland MS 38603; Dear Mr. Bright: This is in reply to your letter of July 19, 1983, to Mr. Vinson of thi office. You have asked whether you are violating any Federal standards or regulations by adding 'right side steering, accelerator, brakes & turn signal controls to rural mail carriers delivery vehicles (cars, pickup, jeeps, etc.).' You have told us that you do not modify in any way the left hand side controls with which the vehicle was originally equipped.; Assuming that your modifications do not affect the performance of an of the systems with which the vehicle was equipped by its original manufacturer, your conversion operations would not be prohibited by the National Traffic and Motor Vehicle Safety Act. However, with respect to any new vehicle that you modify which has not yet reached its first purchaser for purposes other than resale, you are required to affix a label identifying you as the alterer and certifying that the vehicle as altered meets all applicable Federal motor vehicle safety standards. This is required by Title 49 Code of Federal Regulations, Section 567.7. I enclose a copy of Part 567 for your information.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam1575OpenMr. Warren M. Heath, Commander, Engineering Section, Department of California Highway Patrol, P.O. Box 898, Sacramento, CA 95804; Mr. Warren M. Heath Commander Engineering Section Department of California Highway Patrol P.O. Box 898 Sacramento CA 95804; Dear Commander Heath: This is in reply to your letter of July 5, 1974, asking whether consistently with the National Traffic and Motor Vehicle Safety Act, California may amend its vehicle code to permit the use of dark tint glazing material in the rear windows of passenger vehicles following their sale, when they are equipped with outside rearview mirrors on both sides of the vehicle.; Assuming that the material does not conform to Standard No. 205, a amendment such as the one you describe would not be consistent with Motor Vehicle Safety Standard No. 205, and would thus be null and void under section 103(d) of the National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1392(d)). That section preempts State standards which are not identical to Federal standards applicable to the same aspect of motor vehicle or equipment performance.; Standard No. 205 applies to the glazing used in motor vehicles, settin performance and labeling requirements as well as specifying in which vehicle locations various types of glazing materials may be used. The standard does not apply to motor vehicles as such, and your rationale that the standard does not apply after the vehicle's first purchase is inapposite in this case. Unless the glazing you describe meets the requirements for either one of the glazing items listed in ANS Z26.1 or one of the additional items added by Standard No. 205, it cannot be manufactured or sold for use in motor vehicles. Unless occurring after the first purchase of the glazing material for a purpose other than resale, the installation in a motor vehicle of glazing that does not conform to the standard, or its installation in a vehicle location that is not provided for in Standard No. 205, regardless in each case of whether the vehicle is new or used, would be a violation of section 108 of the National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1397), as it would be an introduction into interstate commerce of an item of motor vehicle equipment (the glazing) which did not conform to an applicable standard.; Yours truly, Richard B. Dyson, Acting Chief Counsel |
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ID: aiam2182OpenMr. John W. Kourik, Wagner Electric Corporation, Wagner Division, 11444 Lackland Road, St. Louis, MO 63141; Mr. John W. Kourik Wagner Electric Corporation Wagner Division 11444 Lackland Road St. Louis MO 63141; Dear Mr. Kourik: This responds to Wagner Electric Corporation's October 21, 1975 question whether a trailer would satisfy the requirements of S5.2.1.1 of Standard No. 121, *Air Brake Systems*, to provide a reservoir 'that is unaffected by a loss of air pressure in the service brake system,' if the reservoir provided is either of two service brake system reservoirs on the vehicle, equipped with a pressure protection valve directly adjacent to each reservoir. The drawings enclosed in your letter indicate that the 'protected tank' that is normally provided, separate from the service brake system, would be eliminated and either of the service brake system reservoirs would be used to satisfy S5.2.1.1 in the event of a parking brake application.; Your interpretation of S5.2.1.1 is correct. That section calls for reservoir of air as an energy source that is used to release the vehicle's parking brakes after an automatic or manual application. In requiring that this reservoir be 'unaffected by a loss of air pressure in the service brake system,' the NHTSA means that a single failure of the service brake system would not result in loss of this air supply. With the pressure protection valves located as described in your enclosures, it appears that the system would comply with Section S5.2.1.1.; This 'single failure' requirement must be distinguished from th requirement of S5.6.3 that the energy source for application of the parking brake be 'not affected by loss of air pressure or brake fluid pressure in the service brake system.' The NHTSA has interpreted this requirement to require an uninterrupted energy source despite loss of all air pressure from the service brake system. We recognize that the language of the two passages is substantially identical, and should be changed for clarity.; In a recent proposal to revise the parking brake requirements of th standard (40 FR 56920, December 5, 1975), the NHTSA inadvertently failed to make this distinction clear in its newly-proposed definition of 'parking brake system' and intends to publish a correction of the proposal in the near future.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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.