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: aiam2764OpenMr. W. W. Schwartz, Technical Engineer, Research and Development Dept., Vetter Fairing Company, 1150 Laurel Lane, San Luis Obispo, CA 93401; Mr. W. W. Schwartz Technical Engineer Research and Development Dept. Vetter Fairing Company 1150 Laurel Lane San Luis Obispo CA 93401; Dear Mr. Schwartz: This is in reply to your letter of February 1, 1978, on motorcycl headlighting.; You have asked whether the prohibition in SAE J580a *Sealed Bea Headlamp* against headlamp covers applies to a motorcycle. You have also asked the reason for the prohibition.; Sae J580a *Sealed Beam Headlamp* is incorporated by reference in Tabl III of Standard No. 108 as one of the standards applicable to headlamps for use on multipurpose passenger vehicles, trucks, and buses whose overall width is less than 80 inches. One of the SAE standards incorporated by reference for motorcycle headlighting is J584 which, as an option, allows motorcycles to be equipped with headlamps 'meeting the requirements of SAE J579' (i.e. passenger car sealed beam headlamps). There is no reference in J479a to J580a, and we therefore do not read the prohibition against headlamp covers as applying to motorcycles equipped with sealed or unsealed headlamps.; The reason for the prohibition is the degradation in light output tha can result from condensation under unsealed glass covers or from obscuration by grilles in front of the lens.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam0759OpenMr. T. C. McLaughlin, McLaughlin Equipment Co., Box 2765, 320 27th Street, Fargo, ND 58102; Mr. T. C. McLaughlin McLaughlin Equipment Co. Box 2765 320 27th Street Fargo ND 58102; Dear Mr. McLaughlin: This is in reply to your letter of May 17, 1972, concerning th remounting of old school bus bodies on new chassis. You indicate that this practice is occurring in North Dakota, enclose an advertising brochure of a company that performs the service, and also enclose a copy of a letter from Mr. Robert B. Klure of the Divco-Wayne Corporation which discusses possible safety problems that may result from this practice. You have asked us to outline actions and procedures that can be taken by the NHTSA or your office to curtail this practice.; The NHTSA considers the mounting of an old school bus body on a ne chassis to be manufacturing of a vehicle, which must conform to all applicable motor vehicle safety standards in effect on the day of the manufacture of the chassis, or of the completed vehicle. The failure of a school bus manufactured in this fashion to conform to applicable standards would be a violation of section 108(a)(1) of the National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1397(a)(1)), and could subject its manufacturer to civil penalties and other sanctions. In addition, such vehicles must be certified as conforming to all applicable standards, and the failure of a manufacturer to certify can also result in the imposition of similar sanctions.; It appears from the discussion of safety problems in Mr. Klure's lette that the mounting of old school bus bodies on new chassis creates safety problems that the NHTSA might consider to be safety related defects. If a finding is made by NHTSA that such a defect exists, the manufacturer would be required to notify owners of the defect, and the NHTSA would probably urge the manufacturer to conduct a recall campaign.; In either case the NHTSA will take steps to see that all manufacturer are complying with NHTSA requirements. You can assist us by providing the names of companies which you believe are engaging in this practice. This information should be sent to Mr. Francis Armstrong, Director, Office of Standards Enforcement, National Highway Traffic Safety Administration, 400 7th Street, S.W., Washington, DC 20590.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam3876OpenMr. John S. Cucheran, Vice President, Design and Engineering, Jac Products, Inc., 1901 E. Ellsworth, Ann Arbor, MI 48104; Mr. John S. Cucheran Vice President Design and Engineering Jac Products Inc. 1901 E. Ellsworth Ann Arbor MI 48104; Dear Mr. Cucheran: This is in reply to your letter of November 30, 1984, to Mr. Vinson o this office asking for an interpretation of Motor Vehicle Safety Standard No. 108 *Lamps, Reflective Devices, and Associated Equipment*.; Figure 10 of Standard No. 108 establishes the minimum desig photometrics for center high mounted stoplamps. The test procedure for this particular part of Standard No. 108 which is specified in SAE J186a, stipulates that the 'lamp axis shall be taken as the horizontal line through the light source.' However, I believe that you have misinterpreted the light cone that is involved. The pertinent light cone in this case has its vertex at the photometer and a cross section at the plane of the lamp which encompasses the lens areas. From Drawing A that you have provided, it appears that your rail would interfere with this light cone.; In order to determine if your rack interferes with the photometri requirements, the vehicle must be tested with the rack in position as installed on the vehicle. As the agency has noted before, the photometric requirements do not specify that the entire lens must be visible from each 5 degree down test point. Instead, they specify the intensity of light that must be visible from those points. Therefore, the requirement can be met with a lamp whose lens is partially obscured by a portion of the vehicle when viewed from some of the test points.; We hope that his interpretation is helpful to you. Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam2334OpenMr. W. Wayne Daniel, Wayne Daniel Truck, Inc., P.O. Box 303, Mt. Vernon, MO 65712; Mr. W. Wayne Daniel Wayne Daniel Truck Inc. P.O. Box 303 Mt. Vernon MO 65712; Dear Mr. Daniel: This responds to your June 18, 1976, request for permission t substitute pre-121 brake components for certain components of the brake systems on trucks and trailers you own that were manufactured in conformity with Standard No. 121, *Air Brake Systems*.; From your description, I assume that you intend to remove portions o the brake system that were installed in satisfaction of the requirements of S5.3.1 of Standard No. 121. Section 108(a)(2)(A) of the National Traffic and Motor Vehicle Safety Act (15 U.S.C. S 1397(a)(2)(A)) prohibits, with one exception, knowing disconnection of the antilock system by a manufacturer, distributor, dealer, or repair business.; A person that does not fall into these categories is not prohibite from disconnection of the systems. Thus, it would be permissible for you to make such modifications on your own trucks and trailers. Other State or Federal requirements, such as those of the Bureau of Motor Carrier Safety for operation in interstate commerce, may prohibit disconnection. In any case, the NHTSA urges that you not disconnect safety devices without consulting the vehicle manufacturer with regard to the safest configuration of the vehicle.; Sincerely, Frank Berndt, Acting Chief Counsel |
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ID: aiam0309OpenMr. Eisuke Niguma, Manager, Export Vehicle Engineering Dept., Toyo Kogyo Co., LTD., 6047 Fuchu-Machi, Aki-Gun, Hiroshima 730- 91, Japan; Mr. Eisuke Niguma Manager Export Vehicle Engineering Dept. Toyo Kogyo Co. LTD. 6047 Fuchu-Machi Aki-Gun Hiroshima 730- 91 Japan; Dear Mr. Niguma: This is in response to your letter of March 16, 1971, requestin interpretations of several provisions of the Defect Report Regulations, 49 CFR Part 573.; You ask whether a quarterly report containing the information specifie by section 573.5(b) concerning quarterly motor vehicle production must be submitted for calendar quarters during which no defect notification campaign is conducted. This interpretation is correct. A quarterly report containing the production figures and such other information as may be required by section 573.5 must be submitted for each calendar quarter.; You ask whether the first quarterly report required to be submitte pursuant to section 573.5 need cover only the period from August 16, 1971 (the effective date of the regulation) to September 30, 1971. This interpretation is correct.; Finally, you ask whether the term 'submit', as used in section 573.4(b) and 573.5(a), means 'send'. This interpretation is generally correct. The requirements in these sections for the submission of the defect information and quarterly reports would be satisfied by mailing the reports so that they are postmarked within the specified period of time. For example, defect information reports that are mailed to NHTSA must be postmarked not more than 5 working days after a defect in a vehicle has been determined to be safety- related. However, hand-delivered defect information reports must be received by NHTSA not more than 5 working days after such determination.; Please write if we can be of further assistance. Sincerely, Lawrence R. Schneider, Acting Chief Counsel |
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ID: aiam1148OpenMr. Charles H. Sturgeon, Traffic Manager, Grove Manufacturing Company, Shady Grove, PA 17256; Mr. Charles H. Sturgeon Traffic Manager Grove Manufacturing Company Shady Grove PA 17256; Dear Mr. Sturgeon: This is in reply to your letter of April 23, 1973, requesting ou confirmation of certain issues discussed by you, and Michael Peskoe and David Fay of NHTSA, in a meeting in Mr. Peskoe's office on April 19, 1973.; It is correct that the NHTSA does not presently employ safet inspectors to inspect vehicles in service. Such inspections are made by inspectors of the Bureau of Motor Carrier Safety in the Federal Highway Administration, and it is true that their primary interest is the enforcement of the Bureau of Motor Carrier Safety regulations (49 CFR Parts 301-398). But if these investigators note violations of NHTSA regulations, the information will be forwarded to NHTSA and appropriate action will be taken.; It is correct that components of a vehicle in service may be added removed, or relocated at the discretion of a vehicle owner without violating NHTSA regulations. However, gross vehicle and axle weight ratings established by the vehicle manufacturer must be based on configurations of the vehicle which the manufacturer expects will be utilized in service. It is also correct that the weight imposed on each axle should not exceed the certified weight rating for each axle, but may be less than the certified weight rating.; Finally, it is correct that gross axle weight ratings may b established with a view towards the weight limitations of States in which the vehicle will be used.; Gross axle and vehicle weight ratings, under NHTSA regulations, ar manufacturers' figures, and may be set at any level as long as the figures are consistent with the limitations specified in the NHTSA certification regulations. However, the weight ratings must also, of course, be consistent with the vehicle's load-carrying capacity.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam3175OpenMr. Katsufumi Mitsui, General Manager, Industrial Textile Department, Toray Industries, Inc., 2-2, Nihonbashi-Muromachi, Chuo-ku, Tokyo, Japan; Mr. Katsufumi Mitsui General Manager Industrial Textile Department Toray Industries Inc. 2-2 Nihonbashi-Muromachi Chuo-ku Tokyo Japan; Dear Mr. Mitsui: This responds to a letter we received from Mitsui & Company askin questions concerning the 'resistance to light' test in paragraph S5.1(e) of Safety Standard No. 209, *Seat Belt Assemblies*, as it applies to polyester seat belt webbing. You asked whether it is true that this paragraph will not be enforced for dacron and polyester webbing until an appropriate test method can be incorporated in the standard, and whether such a test method is being developed.; In a July 23, 1976, letter to the Celanese Fibers Marketing Company th agency stated that the Standard No. 209 test procedure for resistance to light was developed to test nylon webbing and that the procedure does not give meaningful results for the new polyester webbings. Therefore, Celanese was informed that the requirement would not be enforced for polyester webbing until a new procedure could be developed. This letter was placed in our public docket for the benefit of all interested parties (in our 'Redbook' interpretations file). The agency does not intend to place an announcement of this interpretation in the *Federal Register*, however, since the standard will soon be amended to incorporate an appropriate test procedure for dacron and polyester webbing.; The new test procedure was developed for the National Highway Traffi Safety Administration by the Narrow Fabrics Institute and the Society of Automotive Engineers Task Force on Webbing. The new procedure would require the use of a plain glass filter instead of the Corex B filter currently required. The agency anticipates rulemaking to incorporate this new procedure sometime early next year, depending on rulemaking priorities.; I am enclosing a copy of our 1976 letter to Celanese for you information.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam1518OpenMr. W. G. Milby, Project Engineer, Blue Bird Body Company, P.O. Box 937, Fort Valley, GA, 81035; Mr. W. G. Milby Project Engineer Blue Bird Body Company P.O. Box 937 Fort Valley GA 81035; Dear Mr. Milby: In your letter of May 30, 1974, you ask whether a rear lightin configuration intended for your 1975 vehicles, based upon a proposal in Docket No. 69-19, would meet the current requirement that stop lamps be 'as far apart as possible.'; The photographs you enclose show that the intent of the proposed S8.1 has been met by providing a separation distance between turn signal and stop lamps that is 5 inches or more, and by placing the stop lamp so that its optical axis is inboard of a vertical longitudinal plane passing through the optical axis of the taillamps. Although it is obviously 'practicable' for you to retain the stop lamps in their present location, we consider that the reasons you wish to introduce the change support a determination of practicability under the current requirements, even though the proposal remains under consideration and may not be adopted.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam3525OpenMr. Leon W. Steenbock, Project Engineer, FWD Corporation, Clintonville, WI 52929; Mr. Leon W. Steenbock Project Engineer FWD Corporation Clintonville WI 52929; Dear Mr. Steenbock: This responds to your recent letter asking whether Safety Standard No 205, *Glazing Materials*, permits the use of Items 4 and 5 rigid plastics in rear windows on fire trucks. You were confused because the 'ANS Z26' standard permits rigid plastics in these locations, yet Standard 205 is silent on the issue.; The fact that Standard No. 205 does not specifically state that Items and 5 rigid plastics may be used in rear windows in trucks does not mean that such use is not permitted. The 'ANS Z26' standard is incorporated by reference in Standard No. 205 (paragraph S5.1.1). Therefore, glazing materials that conform with 'ANS Z26' may be used in the locations specified in that standard. In addition to the requirements and specified locations in 'ANS Z26,' Standard 205 includes other locations and requirements for additional types of glazing, as well as other locations for the Items of glazing that are specified in 'ANS Z26.'; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam3030OpenMr. Donald I. Reed, Director of Engineering, Trailer Manufacturer Association, 401 North Michigan Avenue, Chicago, IL 60611; Mr. Donald I. Reed Director of Engineering Trailer Manufacturer Association 401 North Michigan Avenue Chicago IL 60611; Dear Mr. Reed: This letter corrects an interpretation provided you on June 1, 1979. In our letter, we answered in the negative to your question whether: >>>'whether (sic) it is permissible to combine a clearance lam function in a tail lamp fixture if a second bulb is installed in the tail lamp which, when lit alone, satisfies the photometric requirements of the clearance lamp shown through the tail lamp lens ... and further assuming that all tail lamp photometric requirements are met when the tail lamp bulb alone is lit and when both lamps are lit.'<<<; We commented that such a lamp would appear to create the optica combination prohibited by S4.4.1 when both lamps are lit.; It has been brought to our attention that this conflicts wit interpretations provided on March 4, 1977, to Dennis Moore of Livermore, California, and B.R. Weber of West Bend, Wisconsin, both manufacturers of boat trailer lighting equipment. In our letter to Mr. Weber, for example, we interpreted 'optically combined' to mean a situation in which 'the same light source (i.e., bulb) and the same lens area fulfill two or more functions (i.e., tail lamp, and stop lamp, clearance lamp and turn signal lamp)'. The phrase is not intended to prohibit the installation of two separate bulbs in a single housing and covered by a common lens.; Upon review, we believe that the interpretation of March 4, 1977, i the correct one, and that the conflicting interpretation of June 1, 1979, should be with error. We are sorry for any confusion this may have caused your members.; Sincerely, Frank Berndt, 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.