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: aiam3753OpenMr. Karl-Heinz Ziwicka, Manager, Safety & Emission Control Engineering, BMW of North America, Inc., Montvale, NJ 07645; Mr. Karl-Heinz Ziwicka Manager Safety & Emission Control Engineering BMW of North America Inc. Montvale NJ 07645; Dear Mr. Ziwicka: This is in reply to your letter of August 15, 1983, asking for a interpretation of Federal Motor Vehicle Safety Standard No. 108 with respect to spacing of turn signal lamps on motorcycles.; As you have noted, SAE Standard J588e is the basic Federal requiremen for turn signal lamps referenced by Tables I and III of Standard No. 108 for all motor vehicles. One of the requirements of J588e is that the front turn signal must be separated from the low beam headlamp by at least 4 inches measured from the filament center of the turn signal to the inside diameter of the retaining ring of the low beam headlamp. But, as you further point out, paragraph S4.3.1.7 of Standard No. 108 relieves this restriction under certain circumstances. However, because Table IV of Standard No. 108 specifically requires a minimum edge to edge separation distance of 4 inches between the turn signal lamp and the headlamp on a motorcycle, you believe that it is unclear whether S4.3.1.7 relieves this restriction also, and have asked us for an interpretation that it does.; We are unable to provide the interpretation that you seek. True, SA J588e does incorporate a spacing restriction which is relieved by S4.3.1.7 under certain circumstances. However, although the requirements of J588e generally do apply to motorcycle turn signal lamps, the spacing restriction does not apply, having been superseded by the specific language in Table IV addressed to motorcycles. We believe that it is important to maintain a minimum edge to edge distance on motorcycles that exceeds the minimum allowable on other motor vehicles, in order to assure that the conspicuity of the turn signal will not be masked by the headlamp beam. Because the motorcycle headlamp beam is not fixed in relation to the road as an automobile headlamp is, its vertical and horizontal aim will change with the lean angle and the steering angle of the machine. The higher intensity portions of the beam will rise above the horizontal, thus producing more glare and reducing the conspicuity of the turn signal. Further, given the almost universal daytime use of headlamps, the lesser conspicuity of the turn signal on motorcycles during daylight hours must not be compromised.; I hope that this answers your question. Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam3394OpenMr. M. Iwase, Manager, Technical Administration Dept., Koito Manufacturing Co., Ltd., Shizuoka Works, 550, Kitawaki, Shimizu- Shi, Shizuika-Ken, Japan; Mr. M. Iwase Manager Technical Administration Dept. Koito Manufacturing Co. Ltd. Shizuoka Works 550 Kitawaki Shimizu- Shi Shizuika-Ken Japan; Dear Mr. Iwase: This is in reply to your letter of February 12, 1981, asking whethe the placement of a clear lens cover in front of a motorcycle headlamp would be permissible under Federal Motor Vehicle Safety Standard No. 108.; SAE Standard J580 (both a and b versions) *Sealed Beam Headlam Assembly* is incorporated by reference in Tables I and III of the standard as one of the standards pertaining to headlamps for use on passenger cars, trucks, buses, and multipurpose passenger vehicles. Paragraph 5.2 of J580 states that, 'When in use, a headlamp shall not have any styling ornament or other feature, such as a glass cover or grill, in front of the lens.'; The principal referenced SAE material for motorcycle headlamps is J584 *Motorcycle Headlamps*. As options, both J584 and S4.1.1.34 of Standard No. 108 allow, in effect, a motorcycle to be equipped with one half of any sealed beam system permissible on four-wheeled motor vehicles. We therefore view the prohibition of J580 as applicable to use of any sealed beam headlamp, regardless of the type of vehicle on which it is installed.; Paragraph S4.1.3 of Standard No. 108 forbids the installation o additional equipment 'that impairs the effectiveness of lighting equipment required' by Standard No. 108. Because of moisture accumulation, discoloration, cracks, etc., a glass or plastic cover might tend over a period of time to diminish or distort the headlamp beam. This is of particular concern with reference to the unsealed headlamps implicitly permitted by SAE J584 because of the tendency of the reflector to deteriorate with age.; The agency therefore has concluded that no motorcycle headlamp may hav a glass shield in front of it when in use.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam3761OpenMr. I. A. Wuddel, Westfalische Metall Industrie KG, Hueck & Co., Postfach 28 40, 4780 Lippstadt, Germany; Mr. I. A. Wuddel Westfalische Metall Industrie KG Hueck & Co. Postfach 28 40 4780 Lippstadt Germany; Dear Mr. Wuddel: This is in reply to your letter of September 9, 1983, to August Burget of this agency. With reference to the recent amendment to Motor Vehicle Safety Standard No. 108 permitting semi-sealed replaceable bulb headlamp systems, you have asked whether a headlamp assembly would be allowed which also incorporated a European H1 or H2 bulb, 'for an auxiliary driving beam or a front fog lamp, as our customer requests it.'; It is our understanding that the H1 bulbs are commonly used in Europea lamps as the principal lighting source, and that H2 bulbs are used in high intensity supplemental front lamps. Therefore, use of one of these bulbs in a replaceable bulb headlamp would create, in effect, a system of four headlamps. The agency recently denied a petition by Volkswagen for a four- lamp system at this time using the standardized replaceable light source (copy enclosed), because of unresolved issues. We therefore are currently unable to allow a system such as you propose with the H1 or H2 bulb in a common housing with the standardized replaceable light source, creating in effect a four- lamp headlamp system. Further, paragraph S4.1.3 of Standard No. 108, prohibits the installation of additional lighting equipment which impairs the effectiveness of lighting equipment required by Standard No. 108, and there is the distinct possibility that this could occur through incorporation of the H1 and H2 bulbs.; Use of the H1 and H2 bulbs in separate and independent units fo driving or fog lamps remains permissible, subject to regulation by the individual American States, as these items are not covered by Standard No. 108.; You may be interested to know that Volkswagen of America has recentl petitioned us for rulemaking that would allow use of the H4 bulb instead of the standardized replaceable light source in replaceable bulb headlamp systems. A decision is pending whether to grant this petition.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam3704OpenMr. H. Nakaya, Manager, Mazda (North America) Inc., 23777 Greenfield Road - Suite 462, Southfield, MI 48075; Mr. H. Nakaya Manager Mazda (North America) Inc. 23777 Greenfield Road - Suite 462 Southfield MI 48075; Dear Mr. Nakaya: This is in reply to your letter of May 24, 1983, asking whether th headlamp bezel is considered a 'styling ornament or other feature' for purposes of paragraph 5.2 of SAE J580 *Sealed Beam Headlamp Assembly*, Aug 79 incorporated by reference in Standard No. 108.; The referenced SAE paragraph prohibits styling ornaments or othe features in front of the lens when the headlamp is in use. The intent of this paragraph is to guarantee optimum light output from the headlamp by insuring that no part of the vehicle interferes with the light pattern. If a headlamp bezel is so large that it could interfere with the design light patterns of the lamp, we would consider it a 'styling ornament or other feature' within the meaning of paragraph 5.2.; An oversize bezel interfering with light output would also b prohibited by paragraph S4.1.3 of Standard No. 108 which prohibits installation of motor vehicle equipment that impairs the effectiveness of lighting equipment which the standard requires.; I hope that this answers your question. Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam2232OpenMr. Lawrence MacEachern, Cal Light Co., 50 Oak Court, Walnut Creek, CA, 94596; Mr. Lawrence MacEachern Cal Light Co. 50 Oak Court Walnut Creek CA 94596; Dear Mr. MacEachern: In your latest letter, dated February 17, 1976, you asked 'Does th Federal motor vehicle safety standards allow the use of one half of an automobile headlight system on a motorcycle?'; There is no Federal prohibition against an owner modifying hi motorcycle to use any lighting configuration, though there may be State or municipal restrictions. The answer where a manufacturer is involved, however, depends upon the type of automobile headlamp system used. Motor Vehicle Safety Standard No. 108 requires a motorcycle to be equipped with a headlamp system conforming to SAE Standard J584, *Motorcycle and Motor Driven Cycle Headlamps*, April 1964. Two options allowed are use of a single 7 inch sealed beam unit, or of one 5 3/4 inch Type 1 and one 5 3/4 inch Type 2 sealed beam unit, provided these headlamps meet the requirements of SAE J579a, *Sealed Beam Headlamp Units for Motor Vehicles*, August 1965. Thus, 'one half' of a two-headlamp, or of a four-lamp circular lens passenger car headlighting system could be used on a motorcycle. But use of a system comprised of one Type 1A plus Type 2A (rectangular lens), is not currently permitted under Standard No. 108.; Since there is an equivalence of performance between rectangular an circular lens headlamp systems, if you wish to merchandise a two-lamp (Type 1A plus Type 2A) rectangular system for use on motorcycles, you may wish to submit an additional petition for an amendment of Standard No. 108.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam5015OpenHerr Spingler Robert Bosch GmbH Geschaftsbereich K2 Entwicklung Lichttechnik Systeme Postfach 13 42 D-4710 Reutlingen Germany; Herr Spingler Robert Bosch GmbH Geschaftsbereich K2 Entwicklung Lichttechnik Systeme Postfach 13 42 D-4710 Reutlingen Germany; Dear Herr Spingler: This responds to your letter of April 3, 1992, t Mr. Van Iderstine of this agency asking for a 'quick answer' to your question regarding the acceptability of a new headlamp design. Please be advised that my Office is the one to which questions of interpretation of Motor Vehicle Safety Standard No. 108 should be addressed, and that correspondence addressed to the Chief Counsel allows us to respond more quickly to the concerns of the writer. We understand that you discussed the headlamp with Mr. Van Iderstine on his recent trip to Europe, and that it will be used in a replaceable bulb headlighting system that is governed by S7.5 of Standard No. 108. Your proposed headlamp incorporates a lower beam provided by an ellipsoid and an upper beam provided by a parabola. The drawing you enclosed shows the lower beam source above the upper beam source. When the upper beam is on, both bulbs will be activated simultaneously. Where, as in your design, each headlamp contains two light sources, S7.5(d)(2)(i)(A) and S7.5(e)(2)(i)(A) specify that the lower beam shall be provided by the outboard or uppermost light source. S7.5(d)(2)(ii)(A) and (B) and S7.5(e)(2)(ii)(A) and (B) specify that the upper beam shall be produced by the lowermost, or both, light sources. The beams in your headlamp are provided in this manner, and, therefore, are in accordance with the requirements of Standard No. 108. Sincerely, Paul Jackson Rice Chief Counsel; |
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ID: aiam3010OpenMr. M. Iwase, Chief, Overseas Technical Section, Technical Administration Department, Koito Manufacturing Co., Ltd., Shizuoka Works, 500, Kitawaki, Shimizu-Shi, Shizuoka-Ken, JAPAN; Mr. M. Iwase Chief Overseas Technical Section Technical Administration Department Koito Manufacturing Co. Ltd. Shizuoka Works 500 Kitawaki Shimizu-Shi Shizuoka-Ken JAPAN; Dear Mr. Iwase: This is in reply to your letter of January 29, 1979, to Bill Eason wit respect to headlamp lens marking. Mr. Eason is no longer associated with the Office of Rulemaking and we regret the delay in writing you.; You have asked for a confirmation of your interpretation that: >>>'The headlamp designed to conform to J579c shall be provided wit the lens marking specified in S4.1.1.21 of FMVSS No. 108 *even if the upper beam headlamp maximum output is lower than the conventional maximum restriction of 37,500 cd*.'<<<; You are correct that S4.1.1.21 permits the new code marking fo headlamps designed to conform to SAE Standard J579c even if the upper beam headlamp maximum output is lower than the maximum of 75,000 cds permissible under J579c or the previous maximum of 37,500 cd of J579a. But because the code could be misleading, we are considering proposing an amendment of Standard No. 108 that would delete the new code requirement for all headlamps whose maximum candela does not exceed a certain value, such as 40,000 cd.; Sincerely, Frank Berndt, Acting Chief Counsel |
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ID: aiam4630OpenMr. Victor Crisci 70 Lenox Road Wayne, NJ 07470; Mr. Victor Crisci 70 Lenox Road Wayne NJ 07470; "Dear Mr. Crisci: This is in reply to your letter of June 28, l989, t the former Chief Counsel of this agency, Erika Jones. You intend to install a 'safety light flasher' on your motorcycle, and would like to know whether it would conflict with DOT regulations. The Federal motor vehicle safety standards do not apply to vehicles in use, such as your motorcycle. Further, the National Traffic and Motor Vehicle Safety Act does not prohibit you, as the motorcycle's owner, from personally modifying your vehicle as you see fit, even if doing so adversely affects equipment or safety features installed pursuant to a Federal safety standard. (The Act does prohibit motor vehicle manufacturers, distributors, dealers and repair businesses from making such modifications if they render inoperative, wholly or partially, equipment or safety features installed in accordance with a Federal safety standard). However, modifications by an owner to his or her vehicle are subject to regulation under State and local laws applicable to vehicles in use on their roadways. We are unable to advise you whether New Jersey law specifically covers the addition of the safety light flasher. However, under the Vehicle Safety Act, any laws enacted by a state regarding motor vehicle lighting must be identical to Federal standards covering the same aspects of vehicle lighting performance. The applicable Federal regulation, as you realize, is Motor Vehicle Safety Standard No. l08, a copy of which is enclosed as you requested. As you describe the operation of the flasher, if the headlamp is on (in either beam), the flasher will flash the headlamp between upper and lower beams for 2 to 4 seconds, then returns the light to the beam it was in when the flasher was activated. If the headlamp is off, the flasher will turn it on and initiate an identical flash cycle. The sequence is initiated by pushing the horn button. Standard No. 108 would appear to preclude the installation of your device on new motorcycle, i.e., prior to its first sale to a consumer, or on a used motorcycle, if installed by one of the four entities listed above in the second paragraph. Although paragraph S5.5.10(c) of the standard provides that 'headlamps and side marker lamps may be wired to flash for signalling purposes', that section does not apply to motorcycles since they are not equipped with side marker lamps. The applicable provision for motorcycles is paragraph S5.5.10(d). This states that ' a motorcycle headlamp may be wired to allow either its upper beam or its lower beam, but not both, to modulate from a higher intensity to a lower intensity'. Your system, on the other hand, flashes between beams, which is not permissible. Moreover, motorcycle headlamp modulating systems must also comply with the requirements of paragraph S5.6, and there is no indication that your system would do so. Thus, the answer to your question is that your system would conflict with the Federal regulation applicable to motorcycle lighting if installed under the circumstances described in the preceding paragraph. However, there is nothing under Federal law that prohibits you personally from installing the device on your motorcycle. Sincerely, Stephen P. Wood Acting Chief Counsel Enclosures"; |
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ID: aiam2994OpenMr. C. J. Goode, Chief Engineer, Leyland Cars, P.O. Box 2, Meteor Works, Lode Lane, Solihull, West Midlands B92 8NW, England; Mr. C. J. Goode Chief Engineer Leyland Cars P.O. Box 2 Meteor Works Lode Lane Solihull West Midlands B92 8NW England; Dear Mr. Goode:#I regret the delay in responding to your July 17, 1978 letter petitioning for reconsideration of Federal Motor Vehicle Safety Standard 101-80, *Controls and Displays*. You requested that the standard be amended to add three ISO symbols so that British Leyland could adopt common specifications in satisfaction of both FMVSS 101-80 and EEC directive 78/316. Your petition is in effect granted in part and is denied in part.#You asked that the ISO symbol (an illuminated light bulb) for the Master Lighting Switch be either substituted for Headlamp and Tail Lamp symbol (an illuminated headlamp) specified in Table 1 of FMVSS 101-80 or added as an option to that specified symbol. This aspect of your petition is denied. If a vehicle contains a master lighting control in addition to a headlamp and tail lamp control, the Master Lighting Switch symbol may be used for the master lighting control. We recognize, however, that most vehicles presently sold in this country have one control that operates all lights, including the headlamps and tail lamps. On vehicles having one control for all lights, the control must be identified by the Headlamp and Tail Lamp symbol. We believe that this is appropriate since the headlamps and tail lamps are the most important lights controlled by a master light control. Further, we believe that the Headlamp and Tail Lamp symbol is more easily recognized than the Master Lighting Switch symbol.#You also asked that the ISO symbol for the Manual Choke be added to Table 1 and the ISO symbol for the Brake System be added to Table 2. No amendment of the standard is necessary to permit your use of these two symbols since FMVSS 101-80 does not specify any requirements regarding symbols for those items. Amendment of the standard to require the use of those symbols would require a new proposal to be issued since such an amendment would be beyond the scope of the October 12, 1976, proposal which led to the June 26, 1978 final rule. Treating this part of your petition as a petition for rulemaking instead of a petition for reconsideration, we grant it. It should be understood that granting the petition does not necessarily mean that an amendment will ultimately be adopted.#Sincerely, Michael M. Finkelstein, Associate Administrator for Rulemaking; |
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ID: aiam2995OpenMr. C. J. Goode, Chief Engineer, Leyland Cars, P.O. Box 2, Meteor Works, Lode Lane, Solihull, West Midlands B92 8NW, England; Mr. C. J. Goode Chief Engineer Leyland Cars P.O. Box 2 Meteor Works Lode Lane Solihull West Midlands B92 8NW England; Dear Mr. Goode:#I regret the delay in responding to your July 17, 1978 letter petitioning for reconsideration of Federal Motor Vehicle Safety Standard 101-80, *Controls and Displays*. You requested that the standard be amended to add three ISO symbols so that British Leyland could adopt common specifications in satisfaction of both FMVSS 101-80 and EEC directive 78/316. Your petition is in effect granted in part and is denied in part.#You asked that the ISO symbol (an illuminated light bulb) for the Master Lighting Switch be either substituted for Headlamp and Tail Lamp symbol (an illuminated headlamp) specified in Table 1 of FMVSS 101-80 or added as an option to that specified symbol. This aspect of your petition is denied. If a vehicle contains a master lighting control in addition to a headlamp and tail lamp control, the Master Lighting Switch symbol may be used for the master lighting control. We recognize, however, that most vehicles presently sold in this country have one control that operates all lights, including the headlamps and tail lamps. On vehicles having one control for all lights, the control must be identified by the Headlamp and Tail Lamp symbol. We believe that this is appropriate since the headlamps and tail lamps are the most important lights controlled by a master light control. Further, we believe that the Headlamp and Tail Lamp symbol is more easily recognized than the Master Lighting Switch symbol.#You also asked that the ISO symbol for the Manual Choke be added to Table 1 and the ISO symbol for the Brake System be added to Table 2. No amendment of the standard is necessary to permit your use of these two symbols since FMVSS 101-80 does not specify any requirements regarding symbols for those items. Amendment of the standard to require the use of those symbols would require a new proposal to be issued since such an amendment would be beyond the scope of the October 12, 1976, proposal which led to the June 26, 1978 final rule. Treating this part of your petition as a petition for rulemaking instead of a petition for reconsideration, we grant it. It should be understood that granting the petition does not necessarily mean that an amendment will ultimately be adopted.#Sincerely, Michael M. Finkelstein, Associate Administrator for Rulemaking; |
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.