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: 20674.ztvOpenMr. Vann H. Wilber Dear Mr. Wilber: We are replying to your letter of September 10, 1999, with reference to marking headlamps with the symbol "DOT." Paragraph S7.2(a) of Federal Motor Vehicle Safety Standard No. 108, Lamps, Reflective Devices and Associated Equipment, requires the lens of each headlamp and beam contributor to be marked with the symbol "DOT" to certify its compliance with all applicable requirements. You state that "lens" can be interpreted on some contemporary headlamp designs to "include several elements on the reflector or other interior components that contribute to the photometric performance of the forward light." You ask that we interpret S7.2(a) to allow the DOT symbol to be located on internal optical elements "as long as it is visible from the front when installed on the vehicle without removal of any part." You reference our interpretation of April 25, 1996, to Guy Dorleans "that could appear to conflict with the interpretation we are seeking here," and you seek to distinguish it "on the basis that the question addressed by the agency in that letter apparently presumed that the only 'lens' in the headlamp assembly at issue there was the 'clear lens' in the front of the headlamp housing, whereas the advanced designs we are asking you to consider here include optical elements ('lens') on the interior of the lamp." In the event we cannot distinguish it, you ask that we "reverse the conclusions in that interpretation to the extent they would preclude marking the 'DOT' symbol on interior optical elements." I am sorry to say that we cannot distinguish your request from the Dorleans letter or reverse the conclusions to the extent that we can allow certification to be placed on interior optical elements. As you pointed out, the DOT marking requirement originated as a certification applied to the lenses of sealed beam headlamps. You are correct that Standard No. 108 does not define the word "lens." In the absence of a definition, we believe that the word "lens" has been clearly understood over the years to refer to the glass or plastic front of the headlamp housing through which light is emitted, and not to the other components of a headlamp, the reflector and the light source. Thus, whether a headlamp is sealed beam, replaceable bulb, integral beam, its lens has been clearly identifiable as such for purposes of affixing the DOT marking. We cannot interpret the word "lens" in a manner that departs from the common understanding of the word. However, we intend to address the concern of your members by rulemaking to amend Standard No. 108 to adopt a definition of "lens" broad enough to encompass interior optical elements where the certification symbol could be placed . Sincerely, |
1999 |
ID: nht87-1.17OpenTYPE: INTERPRETATION-NHTSA DATE: 07/13/87 FROM: AUTHOR UNAVAILABLE; Erika Z. Jones; NHTSA TO: Dr. Ernst; Hella KG Hueck & Co. TITLE: FMVSS INTERPRETATION TEXT: Dr. Ernst Hella KG Hueck & Co Postfach 28 40 4780 Lippstadt GERMANY Dear Dr. Ernst: This is in reply to your letter of February 5, 1987, to Richard Van Iderstine of this agency's Office of Vehicle Safety Standards. You have asked for an interpretation of Motor Vehicle Safety Standard No. 108 with respect to a new headlamp manufactured by Hella that BMW has installed on a new car which it introduced in the United States around April 1, 1987. The headlamp is of the replaceable bulb type, and as you describe it consists of two additional parts: "the housing, to which the cover lens is bonded by means of a two "component adhesive", and 'the optical module, consisting of the reflector and the convex lens, joined by the lens carrier...." In your words, "The two parts are held together by three screws", and you believe that "the two parts, firmly screwed together, are as effectively joined as would be the case if bonded". Paragraph S3 of Standard No. 108 defines a "replaceable bulb headlamp" in pertinent part as "a headlamp comprising a bonded lens and reflector assembly. . . ." In the Hella design, the lens and reflector assembly are not bonded, and thus the headlamp is not a "replaceable bulb headlamp" that is permissible for use on motor vehicles sold and used in the Unite States. The intent of the definition is to ensure that the headlamp lens and reflector are an integral replaceable unit, since that is the only means to assure a mechanically aimable replaceable bulb headlamp which is capable of using any replacement standardized replaceable light source and meets the necessary photometric performance. The foundation of mechanical aimability is that the beam and aiming pads are manufactured to have a specific relationship. If this relationship is altered by replacement of the lens only, or of the reflector only, there is a high likelihood that the lamp may not meet minimum performance requirements when aimed mechanically. |
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ID: nht81-2.9OpenDATE: 03/25/81 FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA TO: Koito Manufacturing Co., Ltd. TITLE: FMVSS INTERPRETATION TEXT: This is in reply to your letter of February 12, 1981, asking whether 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 Headlamp 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 J584a 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 of 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 implicity 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 have a glass shield in front of it when in use. |
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ID: nht89-3.20OpenTYPE: INTERPRETATION-NHTSA DATE: OCTOBER 18, 1989 FROM: M. IWASE -- GENERAL MANAGER, TECHNICAL ADMINISTRATION DEPT., KOITO MFG. CO., LTD. TO: ERIKA Z. JONES -- CHIEF COUNSEL, NHTSA TITLE: VEHICLE HEADLAMP AIMING DEVICE (DOCKET NO. 85-15; NOTICE 8) ATTACHMT: ATTACHED TO LETTER DATED APRIL 9, 1990 TO M. IWASE FROM STEPHEN P. WOOD; (A35; STD. 108). ALSO ATTACHED TO LETTER DATED SEPTEMBER 12, 1988 TO M. IWASE FROM ERIKA Z. JONES AND LETTER DATED APRIL 8, 1988 TO ERIKA Z. JONES FROM M. IWASE. TEXT: We would like to again ask your interpretation of FMVSS 108 concerning Vehicle Headlamp Aiming Device (VHAD). In responding to our question dated April 8, 1988, you kindly gave us the interpretation dated September 12, 1988, for which thank you very much. At that stage the provision of VHAD were just a proposal (Notice 5). On May 9, 1989, a final rule (Notice 8) of the VHAD has been issued. Therefore, at this stage when the final rule has been issued, we would again ask and confirm your interpretation, as shown in the attached sheets. Upon your kind review to the above matters, your prompt reply would be greatly appreciated. Encl. Our previous letter of inquiry dated April 8, 1988 Your responding letter dated September 12, 1988. ATTACHMENTS BACKGROUND In a letter dated April 8, 1988, we asked about a detachable spirit level which is installed in the socket by removing a bulb. In responding to our inquiry the agency stated in a letter dated September 12, 1988, as follows; "----- Although the proposal does not specifically prohibit this feature, the test procedures do not anticipate a VHAD design where the light source would be removed and replaced with the VHAD." On account of your advice we recently made some design modification on our detachable spirit level, as shown below: Detachable Spirit Level (Koito's New Design) [GRAPHICS OMITTED] 1) Detachable spirit level is mounted onto a headlamp housing. (Headlamp shall be aimed with bulb remaining in the socket.) 2) Once the headlamp is aimed, the spirit level would be remove to another (the other side) headlamp for aiming it. We are able to provide a single spirit level with each vehicle, which results in a significant cost saving. QUESTION: Could the above detachable spirit level be accepted to the requirements of S7.7.5.2 "On-vehicle aiming" in FMVSS No. 108 ? KOITO'S VIEW: We have carefully reviewed the wording of S7.7 "Aimability Performance", and found that the following provision is specified in S7.7.5.2(c)(1) - "Testing the VHAD"; "The headlamp assembly (the headlamp(s) and the integral or separate VHAD mechanism) shall be mounted on a level goniometer, The above provision in the final rule (Notice 8) allows a detachable spirit level, we think. Structure-2: Detachable Spirit Level [GRAPHICS OMITTED] 1) Spirit level is not permanently fixed onto headlamps. 2) Spirit level is built into bulb gauge. 3) When aiming adjusted, bulb is moved out and Bulb gauge is mounted into reflector socket. 4) Bulb gauge is provided for each vehicle as a standard part. |
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ID: 0437Open Mr. Bryan J Williams FAX 812-467-2388 Dear Mr. Williams: This is in reply to your FAX of October 24, 1994, to Taylor Vinson of this Office requesting an interpretation regarding the relationship of Motor Vehicle Safety Standard No. 108 to an AAMVA list. Your company manufactures UV coatings for polycarbonate headlamp lenses. These "provide abrasion resistance properties as well as protecting the plastic lens from the deleterious effects of outdoor exposure." One of these coatings, UVT200, is used by Ford, General Motors, and Chrysler on headlamp lenses. However, "UVT200 does not appear on the American Association of Motor Vehicle Administrators (AAMVA) 'Listing of Acceptable Plastics for Optical Lenses and Reflectors Used on Motor Vehicles.'" You inform us that some overseas headlamp manufacturers believe that appearance on the list is required by Federal law and is a prerequisite to certification. The question you ask is: Must a coating for plastic (polycarbonate) headlamp lenses appear on the AAMVA "Listing . . ." in order to meet the requirements of FMVSS 108? The answer is no. Paragraph S5.1.2 of Standard No. 108 requires that plastic materials used in lenses (which include headlamp lenses) conform to SAE Recommended Practice J576c, Plastic Materials for Use in Optical Parts, Such as Lenses and Reflectors of Motor Vehicle Lighting Devices, May 1970. Under SAE J576c's outdoor exposure test, the luminous transmittance of the material must not change by more than 25% from its performance before the test. In appearance, the headlamp lens material must not show surface deterioration, crazing, dimensional changes, or delamination. Also, under paragraph S5.1.2(b), after the outdoor exposure test, the haze and surface luster of the material must not be greater than 30 percent haze, as measured by ASTM D-1003-61. Manufacturers have found that a coating is required for the plastics used in headlamp lenses to meet Standard No. 108's outdoor exposure requirements. However, neither SAE J576c or Standard No. 108 require the coating, let alone specify what coating is acceptable. The decision to coat, and the choice of coating, is that of the manufacturer in determining compliance with and certification to Standard No. 108. Therefore, the AAMVA list has no legal relationship to Standard No. 108 and it is immaterial to NHTSA whether the coating used is or is not on the AAMVA list. Sincerely,
Philip R. Recht Chief Counsel ref:108 d:12/7/94
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1994 |
ID: 1983-2.19OpenTYPE: INTERPRETATION-NHTSA DATE: 06/20/83 FROM: AUTHOR UNAVAILABLE; Frank Berndt; NHTSA TO: Mazda (North America) Inc. -- H. Nakaya, Manager TITLE: FMVSS INTERPRETATION TEXT:
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 the 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 other 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 be 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 May 24, 1983
Our Ref. No.: SDL3-016
Mr. Frank Berndt Chief Counsel National Highway Traffic Safety Administration 400 Seventh Street, S.W. Washington, D.C. 20590
Dear Mr. Berndt:
Per a recent phone conversation from a member of my staff to Mr. Taylor Vinson, we request a clarification concerning FMVSS108: Lamps, Reflective Devices, and Associated Equipment.
Our question is: Is the headlamp bezel included in "... any styling ornament or other feature..." which is explained in SAE J530 5.2.
Of course, the performance of the headlamp satisfies all requirements of FMVSS108.
We are looking forward to receiving your response as soon as possible.
Very truly yours,
H. Nakaya Manager
HN/ab
cc: Mr. Taylor Vinson
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ID: nht94-4.97OpenTYPE: INTERPRETATION-NHTSA DATE: December 7, 1994 FROM: Philip R. Recht -- Chief Counsel, NHTSA TO: Bryan J. Williams -- Director, International Operations, Red Spot Paint & Varnish Co Inc. TITLE: None ATTACHMT: ATTACHED TO LETTER DATED 10/24/94 FROM BRYAN J. WILLIAMS TO TAYLOR VINSON (OCC 10437) TEXT: This is in reply to your FAX of October 24, 1994, to Taylor Vinson of this Office requesting an interpretation regarding the relationship of Motor Vehicle Safety Standard No. 108 to an AAMVA list. Your company manufactures UV coatings for polycarbonate headlamp lenses. These "provide abrasion resistance properties as well as protecting the plastic lens from the deleterious effects of outdoor exposure." One of these coatings, UVT200, is used by Fo rd, General Motors, and Chrysler on headlamp lenses. However, "UVT200 does not appear on the American Association of Motor Vehicle Administrators (AAMVA) 'Listing of Acceptable Plastics for Optical Lenses and Reflectors Used on Motor Vehicles.'" You info rm us that some overseas headlamp manufacturers believe that appearance on the list is required by Federal law and is a prerequisite to certification. The question you ask is: Must a coating for plastic (polycarbonate) headlamp lenses appear on the AAMVA "Listing . . ." in order to meet the requirements of FMVSS 108? The answer is no. Paragraph S5.1.2 of Standard No. 108 requires that plastic materials used in lenses (which include headlamp lenses) conform to SAE Recommended Practice J576c, Plastic Materials for Use in Optical Parts, Such as Lenses and Reflectors of Motor Vehicle Lighting Devices, May 1970. Under SAE J576c's outdoor exposure test, the luminous transmittance of the material must not change by more than 25% from its performance before the test. In appearance, the headlamp lens material must not sho w surface deterioration, crazing, dimensional changes, or delamination. Also, under paragraph S5.1.2(b), after the outdoor exposure test, the haze and surface luster of the material must not be greater than 30 percent haze, as measured by ASTM D-1003-61 . Manufacturers have found that a coating is required for the plastics used in headlamp lenses to meet Standard No. 108's outdoor exposure requirements. However, neither SAE J576c or Standard No. 108 require the coating, let alone specify what coating is acceptable. The decision to coat, and the choice of coating, is that of the manufacturer in determining compliance with and certification to Standard No. 108. Therefore, the AAMVA list has no legal relationship to Standard No. 108 and it is immaterial to NHTSA whether the coating used is or is not on the AAMVA list. |
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ID: nht81-2.10OpenDATE: 03/25/81 FROM: FRANK BERNDT -- NHTSA CHIEF COUNSEL TO: STEPHEN W. MATSON -- TRIAD SERVICES INC. TITLE: NOA - 30 ATTACHMT: LETTER DATED 03/10/81 FROM STEPHEN W. MATSON TO NHTSA STD. 108 TEXT: Dear Mr. Matson: This is in reply to your letter of March 10, 1981, asking whether 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 Headlamp Assembly is incorporated by reference in Tables I and III of the standard as one of the standards pertaining to headlamps lamps 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 J584a 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 of 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. 2 The agency therefore has concluded that no motorcycle headlamp may have a glass shield in front of it when in use. Sincerely, |
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ID: 0826Open Mr. Jeffrey D. Shetler Dear Mr. Shetler: We are responding to your FAX of March 29, 1995, to Taylor Vinson of this Office. On May 6, 1994, we advised you that a motorcycle headlamp with an upper beam projector on one side of the vertical centerline and a lower beam projector on the other did not comply with Standard No. 108. You now ask whether the headlamp would comply if an exterior housing were installed on the headlamp which "provides the appearance of two headlamps." This modification in the design does not result in a complying headlamp. Regardless of its exterior appearance, the lamp remains a single headlamp incorporating both an upper and lower beam projector. Since both projectors are within a single headlamp, both projectors must be on the vertical centerline, as specified in Table IV of Standard No. 108. Even if the upper and lower beam projectors were in separate units, neither in itself would be a complying headlamp, and hence not a two-lamp system that could be mounted symmetrically about the vertical centerline. Standard No. 108 does not permit motorcycles to have a headlamp system with asymmetrical beam location. If you have any further questions, you may refer them to Taylor Vinson of this Office (202-366-5263). Sincerely,
Philip R. Recht Acting Chief Counsel ref:109 d:4/24/95
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1995 |
ID: nht95-2.48OpenTYPE: INTERPRETATION-NHTSA DATE: April 24, 1995 FROM: Philip R. Recht -- Acting Chief Counsel, NHTSA TO: Jeffrey D. Shetler -- Manager of Government Relations, Kawasaki Motors Corp. U.S.A. TITLE: NONE ATTACHMT: ATTACHED TO 3/29/95 LETTER FROM JEFFREY D. SHETLER TO TAYLOR VINSON (OCC 10826); ALSO ATTACHED TO 2/7/94 LETTER FROM JEFFREY D. SHETLER TO NHTSA ASSOCIATE ADMINISTRATOR FOR ENFORCEMENT; ALSO ATTACHED TO 5/6/94 LETTER FROM JOHN WOMACK TO JEFFREY D. SHETLER TEXT: Dear Mr. Shetler: We are responding to your FAX of March 29, 1995, to Taylor Vinson of this Office. On May 6, 1994, we advised you that a motorcycle headlamp with an upper beam projector on one side of the vertical centerline and a lower beam projector on the other did not comply with Standard No. 108. You now ask whether the headlamp would comply if an exterior housing were installed on the headlamp which "provides the appearance of two headlamps." This modification in the design does not result in a complying headlamp. Regardless of its exterior appearance, the lamp remains a single headlamp incorporating both an upper and lower beam projector. Since both projectors are within a single headlamp, both projectors must be on the vertical centerline, as specified in Table IV of Standard No. 108. Even if the upper and lower beam projectors were in separate units, neither in itself would be a complying headlamp, and hence not a two-lamp system that could be mounted symmetrically about the vertical centerline. Standard No. 108 does not permit moto rcycles to have a headlamp system with asymmetrical beam location. If you have any further questions, you may refer them to Taylor Vinson of this Office. (202-366-5263). |
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.