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 |
|---|---|
| search results table | |
ID: aiam3902OpenMr. T. Chikada, Manager, Automotive Lighting, Engineering Control Dept., Stanley Electric Co., Ltd., 2-9-13, Nakameguro, Meguro-ku, Tokyo 153, Japan; Mr. T. Chikada Manager Automotive Lighting Engineering Control Dept. Stanley Electric Co. Ltd. 2-9-13 Nakameguro Meguro-ku Tokyo 153 Japan; Dear Mr. Chikada: This is in reply to your letter of January 18, 1985, to Mr. Vinson o this office asking for three interpretations of Motor Vehicle Safety Standard No. 108 with respect to motorcycle lighting.; Your first question is about the location of rear turn signals. Tabl IV of Standard No. 108 requires that rear turn signal lamps on motorcycles have a minimum horizontal separation distance 'centerline to centerline' of 9 inches. You have asked whether this may be interpreted as filament center to filament center., The answer is no. The phrase means the distance from the geometric center of one lamp to the geometric center of the other.; Your second questions concerns the permissibility of an arrangement o lamps on the rear of a motorcycle. There would be a two-compartment combination stop/tail lamp on the vehicle centerline with separate combination lamps below it on either side of the centerline. The distance between filament centers of the separate lamps would be a maximum 16 inches, and there would be the same distance between the filament centers of each separate lamp and the compartment above it belonging to the two- compartment lamp. You have asked whether this is permissible if the minimum design candlepower complies with requirements for three lighted sections in SAE J585e and SAE J586c, and the effective projected luminous lens area of each compartment or lamp is at least 3 1/2 square inches. This arrangement, though unusual, appears to be acceptable. SAE Standard J586c *Stop Lamps* and SAE J585e *Tail Lamps* state that if multiple compartment or multiple lamps are used, and the distance between filament centers does not exceed 16 inches for three compartment or lamp arrangements, the combination of the compartments or lamps must be used to meet the photometric requirements for the corresponding number of lighted sections. Your design has four lighted sections, where as the SAE Tables provide values for only three. In our opinion, your design would be acceptable provided that each of the four compartments meets the minimum value specified for test points in a section when there are three lighted sections.; Your final question concerns a combination stop/taillamp of fou sections, two each on either side of the vertical centerline. Though no distance is given for the filament centers, they appear to be closer than 16 inches. You have asked if this design is permissible provided it meets the requirements for three lighted sections, and the effective projected luminous lens area of each compartment is not less than 3 1/2 square inches. The answer is yes, this is acceptable provided that each of the four compartments meets the minimum value specified for test points in a section when there are three lighted sections.; Sincerely, Frank Berndt, Chief Counsel |
|
ID: aiam1039OpenMr. 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 Mr. Heath: This is in reply to your letter of February 28th to Mr. Douglas W Toms, Administrator, National Highway Traffic Safety Administration, concerning the mounting of lamps and reflectors on mini-pickup trucks.; The December 8, 1972, letter from Commissioner W. Pudinski was place in Docket 69-19, Notice No. 3. We inadvertently failed to knowledge this action to Mr. Pudinski.; The visibility requirements of lamps and reflectors in Standard No. 10 are predicated on the normal driving or closed tail gate position. Since the use of motor vehicles, including driving with tail gates down or trunk lids open or otherwise having lights and reflectors obscured by a particular load on the vehicle, is under the jurisdiction of the individual states, we do not anticipate rule making on this subject.; Sincerely, E. T. Driver, Director, Office of Operating Systems, Moto Vehicle Programs; |
|
ID: aiam3319OpenMr. Dennis Newton, School Pupil Transportation, Kansas Department of Transportation, State Office Building, Topeka, KS 66612; Mr. Dennis Newton School Pupil Transportation Kansas Department of Transportation State Office Building Topeka KS 66612; Dear Mr. Newton: This responds to your June 2, 1980, letter asking whether a school bu that is to be sold to a school district in your State will meet the Federal minimum requirements applicable to gross axle weight ratings (GAWR) and gross vehicle weight ratings (GVWR).; To the best of my knowledge, the Federal government has no minimu specifications for GAWR or GVWR. Certainly, this agency does not specify minimum weight ratings. Our only requirement is that the GAWR and GVWR be appropriate for the size and weight of a vehicle taking into consideration the type of equipment installed on it. From the information that you have provided us, we cannot say that the vehicle in question would or would not comply with that requirement. It is the responsibility of the vehicle manufacturer to certify that its vehicles comply with the Federal safety standards. No school bus manufacturer can sell you a school bus that they know will not comply with the requirements.; Sincerely, Frank Berndt, Chief Counsel |
|
ID: aiam3540OpenMr. M. W. Urban, Sure-View, Inc., 1337 N. Meridan Street, Wichita, KA 67203; Mr. M. W. Urban Sure-View Inc. 1337 N. Meridan Street Wichita KA 67203; Dear Mr. Urban: This responds to your letter of February 8, 1982, concerning complianc with Federal Motor Vehicle Safety Standards, in particular compliance with Safety Standard No. 111, *Rearview Mirrors*.; You are correct that section 102(2) of the National Traffic and Moto Vehicle Safety Act (15 U.S.C. 1392(2)) defines, in part, a motor vehicle safety standard as 'a minimum standard for motor vehicle performance....' Thus, each of the agency's safety standards sets a minimum level of performance which must be met by every manufacturer. Manufacturers are free to utilize designs that exceeds the minimum level of performance set by a standard as long as their products still comply with the standard. Thus, in the case of schoolbus rearview mirrors, a manufacturer must at least comply with the requirements of section 9.1 of Standard No. 111 regarding mirror size, and may voluntarily provide a mirror of a larger size. As explained in the enclosed letter, the Vehicle Safety Act authorizes the agency to regulate aspect of design, such as mirror size.; If you have any further questions, please let me know. Sincerely, Frank Berndt, Chief Counsel |
|
ID: aiam3598OpenMr. Fukuo Takata, Manager, Certifications Regulations Section, Ichikon Industries, Ltd, 80 Itado, Isehara City, Kanagawa 259-11, JAPAN; Mr. Fukuo Takata Manager Certifications Regulations Section Ichikon Industries Ltd 80 Itado Isehara City Kanagawa 259-11 JAPAN; Dear Mr. Takata: This is in reference to your letter of June 30, 1982, to Mr. Elliott o this agency concerning the effective luminous lens area of a front turn signal lamp under Federal Motor Vehicle Safety Standard (FMVSS) No. 108 with respect to three proposed designs.; We assume that you wish to know what is the effective projecte luminous lens area for a front turn signal on vehicles less than 80 inches in overall width. The SAE Standard No. J588e, 'Turn Signal Lamps,' which you quote, imposes no additional requirements for a two compartment front turn signal lamp. Thus, it appears that so long as you meet the minimum of 3.5 square inches for a single compartment lamp, your proposed designs (Case 1 and 2) meet the necessary requirements of FMVSS No. 108. Case 3 would not conform as neither of the two section compartments meets the 3.5 square inch minimum.; Sincerely, Courtney M. Price, Associate Administrator for Rulemaking |
|
ID: aiam3318OpenMr. Dennis Newton, School Pupil Transportation, Kansas Department of Transportation, State Office Building, Topeka, KS 66612; Mr. Dennis Newton School Pupil Transportation Kansas Department of Transportation State Office Building Topeka KS 66612; Dear Mr. Newton: This responds to your June 2, 1980, letter asking whether a school bu that is to be sold to a school district in your State will meet the Federal minimum requirements applicable to gross axle weight ratings (GAWR) and gross vehicle weight ratings (GVWR).; To the best of my knowledge, the Federal government has no minimu specifications for GAWR or GVWR. Certainly, this agency does not specify minimum weight ratings. Our only requirement is that the GAWR and GVWR be appropriate for the size and weight of a vehicle taking into consideration the type of equipment installed on it. From the information that you have provided us, we cannot say that the vehicle in question would or would not comply with that requirement. It is the responsibility of the vehicle manufacturer to certify that its vehicles comply with the Federal safety standards. No school bus manufacturer can sell you a school bus that they know will not comply with the requirements.; Sincerely, Frank Berndt, Chief Counsel |
|
ID: aiam4707OpenMr. T. Chikada Manager, Automotive Lighting Engineering Control Dept. Stanley Electric Co., Ltd. 2-9-13, Nakameguro, Meguro-ku Tokyo 153, Japan; Mr. T. Chikada Manager Automotive Lighting Engineering Control Dept. Stanley Electric Co. Ltd. 2-9-13 Nakameguro Meguro-ku Tokyo 153 Japan; Dear Mr. Chikada: This is in reply to your letter with respect to tw types of decorative lighting devices intended for installation 'on the rear face, and at the top of optional motorcycle rear trunks respectively.' I regret the delay in responding. Type A and Type B would be installed on the same motorcycle. Type A would be installed at the top of the trunk. It consists of an elongated device, illuminated by LEDs when the taillamp is on. Type B is installed on the motorcycle itself. It is a rectangular device, illuminated by an incandescent bulb, which is mounted on the vertical centerline and is flanked by the tail and stop lamps. The distance between the center of the light sources on the two devices is 290mm. (approximately ll 1/2 inches). Both devices emit red light, and their maximum intensity is less than the minimum intensity of the taillamp. You have asked whether it is permitted to equip a motorcycle with the Type A and Type B accessory lamps. If the answer is affirmative, you have asked whether an LED could be used as the light source for Type B. You have also asked whether the maximum intensity of each device separately should be less than the minimum intensity of the tail lamp, or whether the combined maximum intensity of both devices should be less than the minimum intensity of the tail lamp. Paragraph S5.1.3 of Federal Motor Vehicle Safety Standard No. 108 (formerly S4.1.3) permits the installation of these lamps if they do not impair the effectiveness of the lighting equipment required by the standard. In this instance, the question to be asked is whether the devices, activated with the taillamps, impair the effectiveness of the taillamps, or the stop lamps. The devices are, in effect, supplemental taillamps, and as such, arguably do not appear to impair the effectiveness of the taillamps required by the standard no matter what their intensity is. The diagram of Type B indicates that the stop lamps and taillamps are in the same compartment, presumably incorporating a dual filament bulb. Although the stop lamps when activated are brighter than the taillamps, their proximity to the supplemental devices Type A and Type B, each of which are emitting a red light, leads to the possibility that the stop signal would not be as effective as it would be were there no other red lights in the vicinity, and hence impaired within the meaning of S5.1.3. A stop signal must be instantly perceived so that a following driver may determine appropriate action to take. However, we note that this configuration is similar to other stop/taillamp configurations on many vehicles in use on the highways. This would indicate that such configurations do not result in impairment. Thus, the answer to your first question is that both Types of devices are permitted under the standard. Your second question is whether LEDs are acceptable light sources for Type B. Since there is no restriction on light sources for a lighting device not required by Standard No. 108, you may use the LEDs as light sources. Your third question is whether the maximum intensity of Type A and Type B, separately, should be less than the minimum intensity of the taillamp. Even though Type A and Type B are optional devices, in the configuration depicted where Type B is immediately flanked on both sides by a taillamp, the appearance of the three lamps would be that of a multicompartment lamp, even though they may actually be separate. To help assure that impairment of either the taillamp or stop lamp does not occur, the intensity of Type B should be identical with that of the taillamps. Otherwise, observers may assume that Type B (which you intend to have an intensity less than a taillamp) is actually the taillamp, and the actual taillamps (which you intend to have an intensity greater than Type B) might appear to be stop lamps that are continually on. This would be deemed impairment since there would be three intensity levels, increasing the possibility of confusion of the intent of the lamps. As for Type A, its vertical separation decreases the possibility for confusion. If the light sources are LEDs, the color would be a different shade of red that the stop and taillamps. Thus, the intensity is less important. However, it functions as an auxiliary taillamp and should be within the same intensity range as the original equipment taillamps. Finally, you asked whether the combined maximum intensity of both devices would be less than the minimum intensity of the taillamps. Again, this would create three levels of intensity, and could cause confusion in understanding the intent of the lamps. As noted above, the individual intensities should be similar to the intensity of the taillamps. I hope that this answers your questions. Sincerely, Stephen P. Wood Acting Chief Counsel; |
|
ID: aiam3033OpenJohn H. Latshaw, Jr., Esq., Messrs. Topkins, Gammin & Krattenmaker, 151 Tremont Street, Boston MA 02111; John H. Latshaw Jr. Esq. Messrs. Topkins Gammin & Krattenmaker 151 Tremont Street Boston MA 02111; Dear Mr. Latshaw: RE: The Back Rack (T.M.) Carrier by Ennova, Inc. This is in reply to your letter of March 13, 1979, to John Womack o this office on behalf of your client Ennova, Inc. Ennova wishes to market a 'back rack carrier', and you have asked several questions with respect to its legality under Federal requirements. The photographs which you enclosed show that the carrier structure is attached to both the front and rear bumpers, and that loads may be carried on the top of the vehicle as well as on a shelf directly behind the vehicle's rear bumper.; Your questions and our answers are: '1. Are equipment carriers which fasten to a privately owned moto vehicle regulated by the National Highway Traffic and Safety Act (hereinafter, the NHTSA) so that state law in this area is preempted?; 2. Does the NHTSA contain any standards or regulations pertaining t roof racks or equipment carriers? Does the motor vehicle safety act contain any such regulations?'; An equipment carrier that attaches to a motor vehicle is an item o 'motor vehicle equipment' as defined by 15 U.S.C. 1391(4), and your client is a 'manufacturer' as defined by 15 U.S.C. 1391(5). There are no Federal motor vehicle safety standards that cover this type of motor vehicle equipment, and, therefore, a State is not preempted by 15 U.S.C. 1392(d)) (sic) from prescribing its own safety standards for it. If a safety related defect were discovered in the 'Back Rack', Ennova would be responsible for notification and remedy of it, as required by 15 U.S.C. 1411 *et seq*.; '3. Does the NHTSA establish any guidelines for motor vehicle bumper or fenders which the Back Rack (T.M.) Carrier appears to violate? Does the fact that the rear platform extends out behind the vehicle place the Rack in contravention of any Federal standards?; The Back Rack is intended to become affixed to the rear bumper in semipermanent manner and protrude therefrom. Does this bring the carrier into a regulated area? Is (sic) so, what is the citation of the regulations and what must be done to conform the platform to same?; 4. Does the height, width or depth of any aspect of the Back Rac (T.M.) Carrier present a problem?; 5. The structural supports of the Back Rack (T.M.) Carrier obscure th vehicle's lighting in some aspects both front and rear. Does the obstruction violate any provisions of the NHTSA or the Motor Vehicle Safety Act?; 8. If the Back Rack (T.M.) Carrier as it appears in the photograph were installed by a dealer, would it be in contravention of any federal law, standard or regulation exclusive of laws relating to products liability and defective equipment.'; Your questions concern our jurisdiction over a vehicle before and afte its sale to its first purchaser for purposes other than resale. A dealer has the responsiblity (sic) to deliver to its owner a new vehicle in full compliance with all applicable Federal motor vehicle safety standards. Paragraph S4.1.3 of Standard No. 108 prohibits the installation of any 'additional lamp, reflective device, or other motor vehicle equipment ... that impairs the effectiveness of lighting equipment required by this standard.' Paragraph S4.3.1 requires that 'no part of the vehicle shall prevent a parking lamp, taillamp, stop lamp, turn signal lamp, or backup lamp from meeting its photometric output at any applicable group of test points specified in Figures 1 and 3 [Standard No. 108], or prevent any other lamp from meeting the photometric output at any test point specified in any applicable 'SAE Standard on Recommended Practice'. Therefore, a dealer could not deliver a new car with the Back Rack installed if it impairs the effectiveness of the car's lamps or reflectors or impairs photometric output. After sale, a dealer (or distributor or manufacturer, but not the vehicle owner) has a responsibility under 15 U.S.C. 1397(a) (2) (A) of not 'knowingly rendering inoperative in whole or in part, any device or element design installed on ... a motor vehicle ... in compliance with an applicable Federal motor vehicle safety standard ....' In the context of Standard No. 108 we have equated a rendering inoperative with impaired effectiveness or impaired photometrics so that the same consideration would apply, a dealer could not install the Back Rack on a used vehicle if it affects compliance with Standard No. 108.; The installation of the Back Rack appears to present some complianc problems. Based upon an informal review and the photographs you submitted, the front part of the carrier may reduce headlamp candlepower output below the required minimum at several test points, as for example, at test points HV, H-3R and 3L and H 9R and 9L on the upper beam, and at test points 1 1/2 D-2R, 1/2 D-1 1/2 R on the low beam.; Looking at the turn signals which are required to have an 8.0 squar inch minimum projected luminous area, the carrier support design may mask them to the extent that the direction of the turn signal might not be clearly understood. The carrier support location may not allow these lamps to provide an unobstructed effective projected illuminated area of outer lens surface, excluding reflex, of at least 2 square inches, measured at 45 degrees to the longitudinal axis of the vehicle. This requirement must also be met by the taillamps. Further with respect to the taillamps, with the carrier in place, they may not be visible through a horizontal angle from 45 degrees to the left and/or right, as Standard No. 108 requries (sic).; The design location of the carrier supports may reduce the minimu effective projected luminous area of the stop lamps below the 8 square inch minimum of Standard No. 108.; As for backup lamps, the visibility requirements are complex, those o SAE Standard J593c as modified by S4.1.1.22 of Standard No. 108, but in essence the lamps must be 'readily visible' to use your phrase.; These interpretations are based upon the photographs you supplied, an are meant to be illustrative as there are many different lighting configurations on vehicles, and we do not know that the Back Rack would affect compliance in all instances.; '7. What are the dimensional requirements of headlight, parking directional and tail lights? What percentage of these lenses must be totally visible?'; Dimensional requirements of headlights conform to SAE J571d *Dimensional Specifications of Sealed Beam Headlamp Units*, June 1966, parking lights, SAE J 222, *Parking Lamps (Position Lamps)* December 1970, direction lights (turn signals) SAE J588e *Turn Signal Lamps (Rear Position Light)*, August 1970. Copies of the foregoing SAE Standards are attached. In addition, the minima and maxima of lens visibility requirements for parking lamps, turn signal lamps and taillamps are set forth in these SAE Standards. The minimum and maximum photometric requirements of headlights are set forth in SAE J 579a, August 1965 and J 579c, December 1974, as well as the design parameters of rectangular headlamp units SAE J 1132, *Sealed Beam Headlamp Units for Motor Vehicles* (copies also attached).; I hope this answers your questions. Sincerely, Frank Berndt, Chief Counsel |
|
ID: aiam2271OpenMr. Roger E. Stange, President, Norton Triumph Corporation, P.O. Box 275, Duarte, California 91010; Mr. Roger E. Stange President Norton Triumph Corporation P.O. Box 275 Duarte California 91010; Dear Mr. Stange: This is in reply to your letter of April 1, 1976, which requests a interpretation of Motor Vehicle Safety Standard No. 123 as it applies to a motor-driven cycle that your company intends to import.; "The speedometer on this machine displays both minor numerals and mino graduations at 5 mph intervals. Paragraph S5.2.3 and Column 3 of Table 3 of Standard No. 123 require that, if a motorcycle is equipped with a speedometer, 'Major graduations and numerals shall appear at 10 mph intervals, minor graduations at 5 mph intervals.' S5.2.3 also states that the abbreviations used in Column 2 and 3 are j minimum requirements and 'appropriate word may be spelled in full.' It is your interpretation that 'if the abbreviations used in Column 3 are minimum requirements ... the speedometer in question meets the minimum requirements and is therefore in conformity with the standard.'"; The 'abbreviations' only refer to words and not to numerals o graduations. However, since there is no specific prohibition against providing minor numerals at the minor graduations, we have concluded that Standard No. 123 allows a motorcycle manufacturer to furnish a speedometer with them if he so chooses.; Yours truly, Stephen P. wood, Assistant Chief Counsel |
|
ID: aiam2251OpenMr. W. G. Milby, Staff Engineer, Blue Bird Body Company, P.O. Box 937, Fort Valley, GA 31030; Mr. W. G. Milby Staff Engineer Blue Bird Body Company P.O. Box 937 Fort Valley GA 31030; Dear Mr. Milby: This responds to Blue Bird Body Company's March 15, 1976, request fo confirmation that calculation of the material tensile strength of body panels under S6.2(a) of Standard No. 221, *School Bus Body Joint Strength*, is based on the minimum thickness permitted by American Society for Testing and Materials (ASTM) Standard 525 for the thickness specified in ordering the material. This response also reflects the April 1, 1976, meeting held between Blue Bird representatives and National Highway Traffic Safety Administration (NHTSA) personnel at Department of Transportation headquarters.; Under ASTM standards, the thickness of listed materials is permitted t vary from the specified or 'nominal' thickness by a small amount. If the thickness tolerance of a material is specified by the ASTM, the NHTSA bases its determination of thickness on the 'minimum thickness' specified for that material in the 1973 edition of the Annual Book of ASTM Standards. If the thickness tolerance of a material is not specified by the ASTM, the NHTSA uses the minimum thickness permitted by the school bus manufacturer's material specification.; Yours truly, Stephen P. Wood, 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.