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: aiam0189OpenMr. E. W. Bernitt, Vice President, Safety and Quality Assurance, American Motors Corporation, 14250 Plymouth Road, Detroit, MI 48232; Mr. E. W. Bernitt Vice President Safety and Quality Assurance American Motors Corporation 14250 Plymouth Road Detroit MI 48232; Dear Mr. Bernitt: We have received your submittal of consumer information in response t the requirements of 49 CFR Part 375. That regulation requires that manufacturers submit their information to the Administrator 30 days in advance of the time it is made available to prospective purchasers. Since we have not required that this advance submittal be in the same form as that given to prospective purchasers, the following comments are only advisory in nature. There are several respects, however, in which your information, if supplied in this form to prospective or actual purchasers, would not satisfy the requirements of the regulations.; >>>1. The Stopping Distance information is presented as a 'range o stopping distances,' both in numerical and graphical form. The regulations clearly require a single stopping distance figure to be provided for a given group, that can be met or exceeded by all vehicles in the group. We do not know, and consumers surely would not know, the significance of the lower figure given. Even if it were clear, the provision of such additional, non-required information in close proximity to the required data would cause confusion in attempting to compare figures between various makes--the main purpose of the information.; 2. The provision of four sets of data in respect to partial failure o the braking system, for 'fronts operative' and 'rears operative,' and for lightly-loaded and maximum-loaded vehicles, is not in accordance with the regulation requirement that information be provided for the 'most adverse combination' of weights and system failures. As stated in item 1, above, the inserting of this additional information, self-serving in every case since only the worst element should be included, would make comparisons difficult and be unfair to competing manufacturers who followed the regulations strictly.; 3. The form of the Stopping Distance information would fail to satisf the requirement that the information be presented 'in essentially the form illustrated in Figure 1' of 49 CFR S 375.101. In particular, we refer to the placing of two columns side by side instead of the single-axis graph depicted in that figure, and the inclusion of other verbiage between the required statements and warnings and the information itself. The reference to shorter stopping distances with wheel lock-up and without restricting pedal effort, between the required information and the graphs, is especially objectionable, since the safety advantages of avoiding wheel skid were a particular concern in developing this regulation. Although the regulations do not prohibit the provision of other than required information in a Consumer Information booklet, they do require that it be separated in such a manner that the required information, both textual and quantitative, is presented in 'essentially the form illustrated.'; 4. The Tire Reserve Load section of the regulations requires that 'th table that is provided for a specific vehicle shall contain only information that is applicable to that vehicle.' This requirement prohibits a large, all-purpose chart such as yours, with information for many vehicles included on it, at least as far as the information given to the actual purchaser of a vehicle is concerned. More generally, the information is not presented in 'essentially the form illustrated in Figure 1' of 49 CFR S 375.102.; 5. The large, all-inclusive bar graph on Acceleration and Passin Ability does not present the information in 'essentially the form illustrated in Figure 1' of 49 CFR S 375.106, as required.<<<; We will be glad to answer any questions that you may have with respec to the requirements of these or other motor vehicle safety regulations and standards.; Sincerely, Robert Brenner, Acting Director |
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ID: aiam4963OpenDr. Carl C. Clark Safety Systems Company 23 Seminole Avenue Baltimore, MD 21228-5638; Dr. Carl C. Clark Safety Systems Company 23 Seminole Avenue Baltimore MD 21228-5638; "Dear Dr. Clark: This responds to your request for an interpretation o Standard No. 205, Glazing Materials (49 CFR 571.205). More specifically, your letter indicated your belief that Standard No. 205 permits a prime glazing material manufacturer to designate an item of glass-plastic glazing that it manufactures as 'Item 14' glazing if that glass- plastic glazing item passes all the tests specified for Item 14 glazing. It is your view that it is irrelevant whether the individual glass layers in the glass-plastic glazing are tempered or annealed glass. Your understanding is correct. Standard No. 205 specifies the performance requirements for Item 14 glazing, through a series of 14 tests designated for that item of glass-plastic glazing material. No test applicable to Item 14 glazing specifies that any individual layer, either glass or plastic, of this laminated glazing is to be tested separately. Instead, the 14 tests applicable to Item 14 glazing set forth performance levels that must be achieved by the glazing as a laminate. One of the 14 tests designated for Item 14 is Penetration Resistance, Test No. 26. You are correct in noting that, effective September 23, 1991, Test No. 26 specifies the glass-plastic specimen is to be clamped into a test fixture before the specimen is tested. If an item of glass-plastic glazing passes each of the 14 tests applicable to Item 14 glazing, including Test No. 26, with clamping, and complies with Standard No. 205's labeling and certification requirements, the prime glazing material manufacturer of the material may designate that item of glass-plastic glazing as Item 14 glazing. You were also correct in your understanding that Standard No. 205 permits Item 14 glazing to be used for passenger car glazing in any position except the windshield of convertibles. I hope this information is helpful. Please feel free to contact Dorothy Nakama of my staff at this address or by telephone at (202) 366-2992 if you have any further questions or need additional information. Sincerely, Paul Jackson Rice Chief Counsel"; |
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ID: aiam0473OpenMr. Louis C. Lundstrom, Director, Automotive Safety Engineering, General Motors Technical Center, Warren, MI 48090; Mr. Louis C. Lundstrom Director Automotive Safety Engineering General Motors Technical Center Warren MI 48090; Dear Mr. Lundstrom: This is in response to your letter of October 19, 1971, in which yo asked whether the second and third options of Standard 208 require anthropomorphic test devices to be placed for the frontal crash tests only in the front designated seating positions, and not in the rear positions.; The answer is yes. The second and third options pose no requirement for testing that require dummies in the rear positions, hence dummies should be placed only in front positions. In the period from January 1, 1972 to August 15, 1973, they should in fact be placed only in the front outboard positions.; You also suggested that 'if Option 1 is used, a test device must be a each designated seating position.' This statement is true, in a strict sense. But the general requirements for the periods before August 15, 1975 (S4.1.1 and S4.1.2) explicitly allow the 'mixing' of options, so that if belts are provided for the rear seating positions they may be considered as fulfilling option two or three, without dummies positioned there for the crash tests. In other words, dummies must be positioned in the rear seating positions only if and when the manufacturer elects to fulfill option one for the rear positions.; Sincerely, Robert L. Carter, Acting Associate Administrator, Moto Vehicle Programs; |
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ID: aiam0166OpenMr. Francois Louis, Manager, Technical Standards Department, National Service and Parts Division, Renault, Incorporated, 100 Sylvan Avenue, Englewood Cliffs, NJ 07632; Mr. Francois Louis Manager Technical Standards Department National Service and Parts Division Renault Incorporated 100 Sylvan Avenue Englewood Cliffs NJ 07632; Dear Mr. Louis: Thank you for your letter of June 18, 1969, to the U.S. Department o Transportation, concerning your request for clarification of the visibility requirements of back up (sic) lamps as specified in Federal Motor Vehicle Safety Standard No. 108.; The visibility requirements for backup lamps on station wagons o similar type motor vehicles will be predicated on the normal driving, or closed tailgate, position. These lamps may therefore be mounted on the tailgate.; Sincerely, Charles A. Baker, Office of Standards on Accident Avoidance Motor Vehicle Safety Performance Service; |
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ID: aiam5364OpenMartin M. Sackoff, Ph.D. Executive Director of Laboratories International Testing Laboratories 578-582 Market Street Newark, NJ 07015-2913; Martin M. Sackoff Ph.D. Executive Director of Laboratories International Testing Laboratories 578-582 Market Street Newark NJ 07015-2913; "Dear Dr. Sackoff: This responds to your letter to this agency wit reference to Federal Motor Vehicle Safety Standard No. 109, New Pneumatic Tires. Your specific question addressed S4.2.2.4, Tire strength, which states: 'Each tire shall meet the requirements for minimum breaking energy specified in Table I when tested in accordance with S5.3.' You asked for an interpretation of the term 'breaking,' whether it means a blowout of the tire or the breaking of the tire caused by the plunger used in the test specified in the standard. The breaking energy test is a measure of the resistance of the tire to bruise or damage due to impact of the tire with road hazards. This agency tests such resistance in accordance with the procedures of S5.3, Tire strength, of the standard. In that test, a cylindrical steel plunger is forced perpendicularly into the tire rib at the rate of 2 inches per minute at five test points equally spaced around the circumference of the tire. The inch-pounds of force required to push the plunger into the tire is continuously monitored. As the plunger pushes into the tire, the resistance to the plunger force increases. That resistance requires ever-increasing force applied to the plunger to continue pushing it into the tire. Ultimately, one of two things will happen: 1. The plunger will push all the way to the rim, or 2. The tire cords, plies, innerliner, or other components of the tire will stretch, separate, crack or break so that the resistance pressure of the tire diminishes. The 'breaking' of the tire at that point does not require an actual blow-out although, obviously, a blow-out would constitute a 'breaking.' The plunger force is measured just prior to contact with the rim as in 1 above or just prior to the force reduction described in 2 above. The measured force is then combined with the penetration of the plunger into the tire as specified in S5.3.2.3 and S5.3.2.4 of the standard. The breaking energy value of the tire is then determined by computing the average of the values obtained at the five test locations on the tire. Table I, Appendix A of the standard specifies the minimum breaking energy of tires based on tire type, size, composition, and inflation pressure. I hope this information is helpful to you. Should you have any further questions or need any additional information, please feel free to contact Walter Myers of my staff at this address or at (202) 366-2992. Sincerely, John Womack Acting Chief Counsel"; |
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ID: aiam0536OpenJohann und Konen, 53 Bonn-Beuel 1, Rosenbach 32, Ortsteil Putzen, Germany; Johann und Konen 53 Bonn-Beuel 1 Rosenbach 32 Ortsteil Putzen Germany; Gentlemen: This is in reference to your letter of August 22, 1972, requestin information relative to Federal Motor Vehicle Safety Standard No. 125, 'Warning Devices.'; You state that the width of the reflex reflective material in th Warning Triangle you are concerned with is 1.6732 inches, and inquire whether it is permissible to utilize 'for manufacturing reasons' a non-reflective border around the reflective material which would increase the width of the red reflective section to 1.8504 inches.; Paragraph S5.2.2 of Standard 125 specifies that the width of each o the three sides of the triangular portion of the warning device shall be not less than 2 and not more than 3 inches wide, as depicted in Figure 1. If the required widths specified in S5.2.5 for the red reflex reflective and orange fluorescent materials are met, provision of non-reflective or non-fluorescent 'border' material is permitted, as long as the overall width requirements for the side of the triangle are also met.; I hope this answers your questions. Sincerely, E.T. Driver, Director, Office of Operating Systems, Moto Vehicle Programs; |
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ID: aiam4826OpenMr. Gene Schlanger President ROC Capital, Inc. 63 Greens Road Hollywood, FL 33021; Mr. Gene Schlanger President ROC Capital Inc. 63 Greens Road Hollywood FL 33021; "Dear Mr. Schlanger: This is in reply to your FAX of January 3, l991 to Taylor Vinson of this Office, asking about the permissibility under Federal and State regulations of a 'lighted sign' on which messages could be scrolled from left to right. Such a sign 'is designed to be mounted inside the car, either on a rear or side window.' However, 'if that is deemed legally inappropriate, the sign can be designed to be placed outside on the roof of the auto.' The sign would incorporate LEDs and would not project a beam or flash. You intend to sell it 'to the general public.' The National Highway Traffic Safety Administration has no specific Federal motor vehicle safety standard that addresses your device, nor any prohibition against your selling it. The question arises, however, as to whether and under what circumstances Federal law may allow its use. As a general rule, aftermarket equipment such as this is acceptable under Federal law provided that its installation by a manufacturer, distributor, dealer, or motor vehicle repair business, does not entail removal of, or otherwise rendering inoperative, in whole or in part, equipment installed in accordance with a Federal motor vehicle safety standard. This means that removal by any of the persons just mentioned of the high-mounted stop lamp that has been required on passenger cars manufactured on or after September 1, l985, in order to substitute your lighted sign, would be a violation of Federal law. The question arises of whether the lighted sign may be installed in the rear window of any other vehicle, or in a passenger car manufactured before September 1, l985, or on the top of any vehicle, situations where there is no direct removal of safety equipment. The agency regards any impairment of the effectiveness of rear lighting equipment as tantamount to rendering it partially inoperative. Thus, if aftermarket equipment is likely to create confusion or distraction in a following motorist, we regard it as likely to impair the messages that required lighting equipment is supposed to impart. A lighted sign with a changing message is likely to create a distraction, diverting attention from signals sent by stop lamps or turn signal lamps. Thus, we believe that this device has the potential of rendering those lamps partially inoperative within the meaning of the statutory prohibition. Even when installed in a side window, where it may not be visible directly to the rear, the device has the potential of distraction when the vehicle carrying it is approached in other lanes, i.e., at an angle from the rear. We are unable to tell you whether the device is illegal under the laws of each of the 50 States. If you are interested in pursuing this question, we recommend that you consult the American Association of Motor Vehicle Administrators, 4600 Wilson Boulevard, Arlington, Va. 22203. Sincerely, Paul Jackson Rice Chief Counsel"; |
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ID: aiam1777OpenMr. C. M. Xeros, Chief Engineer, Marmon Motor Co., P.O. Box 5175, Dallas, TX 75222; Mr. C. M. Xeros Chief Engineer Marmon Motor Co. P.O. Box 5175 Dallas TX 75222; Dear Mr. Xeros: This responds to your January 15, 1975, request for confirmation that vehicle is complete for purposes of establishing its 'date of manufacture' and the applicability of Federal motor vehicles safety standards, although minor finishing operations and the attachment of mirrors, grab rails, etc. have not been accomplished.; As you describe the type of minor finish work and readily attachabl components which remain uncompleted, your vehicles would be complete for purposes of establishing 'date of manufacture.' I enclose a discussion of this concept as it applies to truck, bus, and trailer manufacture under Standard No. 121, *Air brake systems*.; Yours truly, Richard B. Dyson, Acting Chief Counsel |
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ID: aiam0865OpenMr. Gerald D. Stapley, K-146 Northwood Apartments, Capital Hill Drive, RFD-2, Londonderry, NH 03053; Mr. Gerald D. Stapley K-146 Northwood Apartments Capital Hill Drive RFD-2 Londonderry NH 03053; Dear Mr. Stapley: This is in reply to your letter of September 9, 1972, proposing 'tha legal standards for the performance of windshield defrosting systems be established and applied to vehicles manufactured in or imported into USA.'; The National Highway Traffic Safety Administration has opened Docke No. 1-3 to receive comments on extension of coverage of the passenger car defrosting and defogging system standard, Federal Motor Vehicle Safety Standard No. 103, to multipurpose passenger vehicles, trucks, and buses. Ice or slush buildup on the windshield, as well as the overall performance of the defroster system, are among the problems and concerns currently being investigated by the NHTSA.; We plan to combine all the problems associated with vision an precipitation into an Adverse Weather Visibility standard such as you suggest in your letter. This would also include wiping and washing requirements. At the present time research has been initiated to obtain data so that we can propose definite performance requirements for all types of weather conditions. Under our Program Plan such a standard would become effective September 1, 1976.; Your suggestion and the mention of the specific problems ar appreciated and will be considered as we proceed in our rulemaking. Thank you for writing and if we can be of further service, please let us know.; Sincerely, E. T. Driver, Director, Office of Operating Systems, Moto Vehicle Programs; |
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ID: aiam2858OpenMr. J. W. Yarbrough, Assistant Superintendent for Business, West Seneca Central School District, 45 Allendale, West Seneca, NY 14224; Mr. J. W. Yarbrough Assistant Superintendent for Business West Seneca Central School District 45 Allendale West Seneca NY 14224; Dear Mr. Yarbrough: This responds to your May 4, 1978, letter asking whether you can modif several buses that you have purchased by adding stanchion bars near the front door to facilitate the loading of smaller school children.; The National Highway Traffic Safety Administration does not prohibi the use of stanchion bars in school buses. Some manufacturers, however, have discontinued putting them in buses because it is difficult to pad them sufficiently such that they comply with the head impact zone requirements when the bars fall within the head impact zone.; The National Traffic and Motor Vehicle Safety Act of 1966 (the Act prohibits modification of vehicles by repair businesses, dealers, or manufacturers that would render inoperative compliance with safety standards (section 108(a)(2)(A)). Therefore, if a dealer, repair business, or manufacturer were to install stanchion bars in your school buses, it would be required to ensure that the installation does not render inoperative compliance with the head impact zone requirements. The Act does not prohibit, however, modifications by individuals of their vehicles even when such modification would not comply with Federal safety standards. Accordingly, a school district could itself install stanchion bars that do not comply with the head impact zone requirements.; 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.