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: aiam3871OpenMr. Donald W. Vierimaa, Director of Engineering, Truck Trailer Manufacturers Association, 1020 Princess Street, Alexandria, VA 22314; Mr. Donald W. Vierimaa Director of Engineering Truck Trailer Manufacturers Association 1020 Princess Street Alexandria VA 22314; Dear Mr. Vierimaa: This is in reply to your letter of December 7, 1984, asking ou 'concurrence that the front clearance lamps on a trailer with a low front end or one designed to be equipped with a tarpaulin...may be mounted at the trailer frame level (about 50 inches above the ground), to avoid these lamps reflecting into the driver's eyes by way of the side view mirror.'; You thoughtfully attached a copy of my letter to you of November 10 1981 in which I advised you that 'the determination of practicability is one that is made by the manufacturer of the trailer', and that 'NHTSA will accept a determination that mounting clearance lamps at the top...is not practicable if such lamps are reflected into the driver's eyes by way of the side view mirror.' That remains our view if the configuration of any trailer is such that location of clearance lamps at or near the top of the trailer results in the reflection of the light into the eyes of the driver of the truck tractor.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam0873OpenMr. Heinrich von Wimmersperg, Development Engineer, 15929 Grand River Avenue, Detroit 27, MI; Mr. Heinrich von Wimmersperg Development Engineer 15929 Grand River Avenue Detroit 27 MI; Dear Mr. von Wimmersperg: Thank you for your letter of October 2, 1972, concerning the For 'Tot-Guard' and your child restraint patents.; The consumer complaints that we have received on the Ford Tot-Guar have been complaints focussing on the fit of the device for minimum recommended size children. The comments relate both to the ease with which small children may climb out of the device and slide under it, as well as to the vision restriction problem for the small child.; The Tot-Guard has proven to perform well in 30 mph frontal impacts wit the three- year-old child dummy in our research programs, but can be improved in lateral protection capability and in performance with the 50-pound child dummy.; We have just completed a research program to develop new concepts i child restraints and will very shortly be making these designs available for any manufacturer who chooses to produce one of these advanced design restraints.; A copy of your letter will be placed in the public docket along wit plans for the restraints developed on our child restraint development contract.; We are interested in reviewing and placing in the public docket copie of your designs for the infant car bed, which you mention in hopes of stimulating the production of a crashworthy design for such a device.; We appreciate your letter and are looking forward to hearing from yo in the near future.; Sincerely, Douglas W. Toms, Administrator |
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ID: aiam0117OpenMrs. Jerry E. Anderson, Tejas Campers, 5125 College, Beaumont, TX 77707; Mrs. Jerry E. Anderson Tejas Campers 5125 College Beaumont TX 77707; Dear Mrs. Anderson: Thank you for your letter of August 19, 1968, concerning glazing an lighting requirements in campers.; The amendment to Standard No. 205 to which you refer, Docket No. 23, i enclosed along with a copy of FHWA Ruling 68-1. The amendment does not allow AS2 tempered glass to be placed in forward facing windows of campers. Forward facing windows of campers must be AS1, AS2 laminated that meets the requirements of test no. 26 of ASA Standard Z26.1 - 1966, or AS3 laminated that meets the requirements of test no. 26 of ASA Standard Z26.1 - 1966. Rigid plastics may be used in other windows.; With respect to your question on vehicle lighting requirements enclosed is a copy of Federal Motor Vehicle Safety Standard No. 108, effective January 1, 1969. You will note from the standard that clearance lamps are not required on vehicles less than 80 inches in overall width. The specified requirements for side marker lamps and side reflex reflectors on vehicles of less than 80 inches in overall width are contained in paragraphs S3.1.1.6 and S3.1.1.8 and Tables III and IV of Standard No. 108.; I have had your name added to our mailing list for all rulemaking related to multipurpose passenger vehicles and trailers and I have also enclosed information on subscribing to the *Federal Register* should you so desire.; Sincerely, Clue D. Ferguson, Director, Office of Standards o Crash-Injury Reduction, Motor Vehicle Safety Performance Service; |
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ID: aiam4287OpenMr. Hiromi Hori, Manager, Certification Regulations Section, Technical Department, Ichikoh Industries, Ltd., 80 Itado,, Isehara- City, Kanagawa Pref. 259-11, Japan; Mr. Hiromi Hori Manager Certification Regulations Section Technical Department Ichikoh Industries Ltd. 80 Itado Isehara- City Kanagawa Pref. 259-11 Japan; Dear Mr. Hori: This is in reply to your letter of January 12, 1987, with reference t a lamp that is used as both an identification lamp, and as a clearance lamp. Currently the lamp projects its amber beam forward as much of the remainder of the lens is painted black. You have asked if it is permissible to remove the black paint, as a result of which the lamp will emit light in other directions.; Standard No. 108 does not prohibit removal of the black paint. Th lamp, of course, must meet the photometric requirements for a clearance lamp, or for an identification lamp if it is used as part of the three lamp array. We call your attention to paragraph 3.4 of SAE Standard J592e, July 1972, incorporated by reference in Standard No. 108. It states that 'The H-V axis of a clearance or identification lamp shall be taken as parallel to the longitudinal axis of the vehicle.' The lamp depicted in your sketch appears to conflict with this requirement. Further, if the lamp is mounted as shown in the sketch, it would appear that no light will be visible, except in that half of the pattern on the lens side of the lamp base.; I hope that this answers your question. Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam2816OpenMr. Robert J. Voshell, Director, Motor Vehicle Division, State of Delaware, P.O. Box 698, Dover, DE 19901; Mr. Robert J. Voshell Director Motor Vehicle Division State of Delaware P.O. Box 698 Dover DE 19901; Dear Mr. Voshell: This is in reply to your letter of May 18, 1978 which asks th following questions:; >>>'Is there a Motor Vehicle Safety Standard which requires al motorcycles to be equipped with turn signals, other than those expressly exempted under FMVSS 108 (whose speed attainable in 1 mile is 30 mph or less) S4.1.1.26?'<<<; Yes. Paragraph S4.1.1 of Standard No. 108 requires, in part, that moto vehicles be equipped with the lamps specified in Table III. Turn signal lamps are required for motorcycles under Table III.; >>>'Does the standard apply to only highway-use vehicles wit trail-bikes exempted?'<<<; Yes. The motorcycles covered by Standard No. 108 must be 'moto vehicles' in the first instance, in order to be subject to the regulatory authority of the National Traffic and Motor Vehicle Safety Act. A 'motor vehicle' is one 'manufactured primarily for use on the public streets, roads and highways'. This would exclude a trail bike unless its manufacturer had certified it to meet all applicable Federal motor vehicle safety standards, indicating his intent that it be used on-road as well as off-road.; We are enclosing a copy of Standard No. 108 as you requested. Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam0705OpenMr. John W. Kourik, Chief Engineer, Automotive Products, Wagner Electric Corporation, 11444 Lackland Road, St. Louis, MO 83141; Mr. John W. Kourik Chief Engineer Automotive Products Wagner Electric Corporation 11444 Lackland Road St. Louis MO 83141; Dear Mr. Kourik:The following interpetations (sic) are submitted i response to your letter of March 16, 1972, concerning Federal Motor Vehicle Safety Standard No. 121, *Air Brake Systems* and are numbered as the questions were in your letter.; >>>1. The 30 skid number surface referred to in the Standard is wet an measured by the ASTM B-274-65T procedure omitting water delivery as specified in paragraph 7.1 of that procedure.; 2. In S5.1.6 total electrical failure 'means any electrical failur within the antilock electrical system circuitry which would cause loss of antilock control of every wheel on the vehicle.; 3. S5.1.6 does not at present require the activation of the antiloc warning device so long as proper antilock control remains on at least one wheel or axle.; 4. The requirement for an antilock warning device is not limited to failure in the power supply at the antilock electrical connection. However, an electrical failure in a vehicle which causes failure of the whole vehicle electrical system is not expected to activate the warning system since there would be no power to energize it.; 5. In S5.1.7, for air over hydraulic brake systems, the 6 psi pressur is measured in the power air chamber coupled to the master cylinder used to convert air pressure to hydraulic pressure.; 6. The wording of S5.1.7 is not intended to exclude the use of an auxiliary hand application valves for controlling the trailer brakes as long as there is also a foot treddle valve which controls the brakes of the towing vehicle and any towed vehicle.; 7. The stoplight on a trailer is to be actuated whenever the servic brakes on the trailer are applied. S4.5.3 of FMVSS No. 108 states 'the stoplamps on each vehicle shall be activated upon the application of the service brakes.'; 8. The intent of S5.2.1.2 is for the service reservoir capacity, to b eight times the combined volume of all of the service brake chambers.; 9. In S5.3.2 the 90 psi pressure is to be fully applied to the traile at the start of the stop.; 10. In S5.3.2, the air compressor and air supply system of the towin vehicle are expected to be operating normally.; 11. In S5.3.3, the towing vehicle brakes may be by-passed by an convenient means so long as it does not cause the air pressure applied to the trailer to fall below 90 psi.; 12. In S5.3.2, item 4 and 5 of Table I are not applicable. 13. A truck tested brake may be run on a dynamometer by a manufacture for his own purposes but compliance with S5.4.1, S5.4.2 and S5.4.3 of the Standard will be determined by the Government by testing a new brake assembly identical to the one on the vehicle.; 14. Same answer as for 13 above. 15. The intent of S.5.4 is for a new brake assembly identical to th one on the vehicle to be tested on a dynamometer for conformance with S5.4.1, S5.4.2 and S5.4.3.; 16. Same as answer for 15 above. 17. In S5.4.1, S5.4.2 and S5.4.3, for air or hydraulic brake systems the 'brake chamber air pressure' is the air pressure in the power chamber coupled to the master cylinder usedto (sic) convert air pressure to hydraulic pressure.; 18. Same answer as for question 17. 19. The Standard does not consider tandem ratings, it addresses onl the GAWR of each individual axle.; 20. Vehicles conforming to S5.6.1 must have a parking brake on eac individual axle of a tandem axle arrangement.; 21. In S5.6.2(a) 'Gross vehicle weight rating' is correct fo semi-trailers as well as trucks and buses, gross axle weight rating is not meant.; 22. Semi-trailers are not excluded from meeting the alternat requirement of S5.6.2.; 23. A dolly is classified as a trailer and is a separate vehicle. 24. In S5.6.2, the unloaded dolly weight does not include an unloade semi-trailer.; 25. In the dynamometer test conditions of S6.2.1, the dynamomete inertia for each brake assembly is based on 1/2 the GAWR of the axle. The rating for each axle is required to be stated separately. If, in the example you give, you choose to give 17,000 pounds as the rating for each axle, then the dynamometer inertia would be at 8,500 pounds for each brake assembly.<<<; Sincerely, E. T. Driver, Director, Office of Operating Systems, Moto Vehicle Programs; |
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ID: aiam0056OpenMr. David A. Phelps, Jr., Engineering Services, Blue Bird Body Company, Fort Valley, GA 31030; Mr. David A. Phelps Jr. Engineering Services Blue Bird Body Company Fort Valley GA 31030; Dear Mr. Phelps: Thank you for your letter of March 19, 1968, to Mr. George C. Nield requesting a clarification of paragraphs S3.4.4 and S3.4.4.1 of Motor Vehicle Safety Standard No. 108.; In your letter you listed possible brake combinations as follows:>>>1 A vacuum over dual hydraulic brake system and a hand operated mechanical brake are provided.; 2. A full air brake system and a hand operated mechanical brake ar provided.; 3. A full air brake system with a spring loaded emergency stoppin system which is actuated at a pre-determined low air pressure level and a hand operated mechanical brake are provided.<<<; In accordance with the interpretation issued February 27, 1967, (3 F.R. 3390, copy enclosed), on 'emergency brakes,' the supplementary brake systems included in the above brake combinations are not emergency brakes. Therefore, paragraph S3.4.4 of Standard No. 108 does not require that the stop lamp be actuated upon application of these supplementary brakes.; Thank you for writing. Sincerely, David A. Fay, Office of Standards on Accident Avoidance Motor Vehicle Safety Performance Service; |
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ID: aiam3699OpenMr. Stephen E. Parmeter, Route 4, Potsdam, NY 13676; Mr. Stephen E. Parmeter Route 4 Potsdam NY 13676; Dear Mr. Parmeter: This responds to your recent letter concerning the process of repairin breaks in automobile windshields. You ask whether such repairs would conflict with any present Federal motor vehicle safety standards.; The National Highway Traffic Safety Administration has issued Federa Motor Vehicle Safety Standard No. 205 which specifies performance and location requirements for glazing materials used on motor vehicles (copy enclosed). This standard would not apply to a repair process such as you describe, however. There is no Federal regulation which would prohibit the use of a product or process in the repair of windshields which have previously been installed in vehicles and damaged in use.; Please note, however, that using such a material or process in a ne windshield which may require repair (as a result of damage sustained, for example, in shipment) could cause the windshield to fail to meet the performance requirements of Safety Standard No. 205, or could fail to bring a noncomplying windshield back into compliance. Either case of noncompliance would be the responsibility of the person selling the windshield (49 CFR 567.7, copy enclosed). Therefore, we do not recommend use of windshield repair processes prior to the first purchase of a new windshield by a consumer.; You will have to contact a private attorney to determine your liabilit under civil law with regards to such a business.; Please contact Hugh Oates of my staff if you have any furthe questions.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam5409OpenJames H. Shuff, President Freedom Trailers P.O. Box 31, Brownfield Road Eaton, NH 03832; James H. Shuff President Freedom Trailers P.O. Box 31 Brownfield Road Eaton NH 03832; "Dear Mr. Shuff: This responds to your letter asking whether tires an wheel rims used with your 'park model travel trailers' are subject to Federal Motor Vehicle Safety Standard (FMVSS) No. 120, Tire selection and rims for motor vehicles other than passenger cars. As explained below, the answer is no, because your travel trailers are not motor vehicles. Your letter provided the following information about your 'trailers.' The trailers are intended for recreational use, rather than for year round living. Each unit is a maximum of 400 sq. ft., and may be as wide as 12 feet. You state that after your trailers are constructed, they 'will be towed to their campsite and set up,' where they may be used for 'winter camping in the year round parks.' Once your trailers are set up, you would reuse the tires and rims. By way of background, 49 U.S.C. 30101 et seq. authorizes NHTSA to regulate new motor vehicles and motor vehicle equipment, including tires and rims. Standard No. 120, and all of our safety standards, apply only to vehicles that are 'motor vehicles,' within the meaning of the statute. The term 'motor vehicle' is defined at 49 U.S.C. 30102(a)(6) as: 'motor vehicle' means a vehicle driven or drawn by mechanical power and manufactured primarily for use on public streets, roads, and highways, but does not include a vehicle operated only on a rail line. We have determined that your 'trailers' are not motor vehicles based on two examinations. First, while the characteristics of your trailers are not entirely clear in your letter (our repeated attempts to reach you by telephone have been unsuccessful), it appears that your trailers could be considered 'mobile homes.' Mobile homes are regulated by the U.S. Department of Housing and Urban Development (HUD), and are not 'motor vehicles' subject to regulation by NHTSA. Accordingly, tire and rim selection for mobile homes is not subject to Standard No. 120 or any other NHTSA regulation. For information about mobile homes, you can contact the Assistant Secretary for Housing-Federal Housing Commissioner, U.S. Department of Housing and Urban Development, 451 7th St., SW, Washington, DC 20410. Second, even if your 'trailer' is not a mobile home, it does not meet the Safety Act definition of a 'motor vehicle.' We have interpreted the definition as follows. Vehicles designed and sold solely for off-road use are not considered motor vehicles, even though they may be operationally capable of highway travel. Vehicles, such as mobile construction equipment, that use the public roads only to travel between job sites and which typically spend extended periods of time at a single job site, are not considered motor vehicles. In such cases, the use of the public roads is incidental, not the primary purpose for which the vehicle was manufactured. On the other hand, if a vehicle is readily usable on the public roads and is in fact used on the public roads by a substantial number of owners, NHTSA has found the vehicle to be a motor vehicle. This finding was made with respect to dune buggies and regardless of the manufacturer's stated intent regarding the terrain on which the vehicles were to be operated. Based on your description, it appears that, analogous to mobile construction equipment, the on-road use of your travel trailers appears to be incidental and not the primary purpose for which they are manufactured. Therefore, your trailers are not subject to Standard No. 120's requirements for tire selection and rims. Please note that this conclusion is based solely on the facts presented in your letter. We may reexamine this conclusion if additional information becomes available that would warrant a reexamination. I hope that this information is helpful. If you have any questions, please contact Dorothy Nakama of my staff at this address or at (202) 366-2992. Sincerely, John Womack Acting Chief Counsel"; |
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ID: aiam2906OpenMr. T. F. Brown, Mack Trucks, Inc., P.O. Box 1761, Allentown, PA 18105; Mr. T. F. Brown Mack Trucks Inc. P.O. Box 1761 Allentown PA 18105; Dear Mr. Brown: This responds to your October 10, 1978, letter asking whether you ar permitted to mark the certification documents of some of your incomplete vehicles as MACK TRUCKS, INC./RVI. These incomplete vehicles will be manufactured abroad by Renault Vehicules Industriels and imported in the United States by Mack Trucks, Inc.; Part 568, *Vehicles Manufactured in Two or More Stages*, requires a incomplete vehicle manufacture to furnish with the incomplete vehicle certification its name and mailing address. Section 102(5) of the National Traffic and Motor Vehicle Safety Act states that the term manufacturer includes any person importing motor vehicles or motor vehicle equipment. Since your company will be importing these incomplete vehicles and an importer may be considered a manufacturer, it is permissible for you to label incomplete vehicles assembled by Renault with the MACK TRUCKS, INC./RVI designation.; Sincerely, Joseph J. Levin, Jr., 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.