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: aiam4355OpenMr. Yueh-An Chen, Division Head, Planning Division, Yue Loong Motor Engineering Center, P. O. Box 510, Taoyuan, Taiwan 330, Republic of China; Mr. Yueh-An Chen Division Head Planning Division Yue Loong Motor Engineering Center P. O. Box 510 Taoyuan Taiwan 330 Republic of China; Dear Mr. Chen: This is in reply to your letter of June 5, 1987, asking whether certai rear lighting arrangements are acceptable under Federal Motor Vehicle Safety Standard No. 108.; You have submitted a diagram showing four lamps on either side of th vertical centerline of the rear of the car. The most inboard lamps, denoted 'R', are the backup lamp system. Yue Loong contemplates four different functions for the remaining three systems of lamps, 'A', 'B', 'C', and 'D', 'E', 'F' (inboard to outboard) and asks about acceptability.; >>>1. In the first system, ABC or DEF will serve the respective tur signal functions. All lamps would serve as hazard warning signal lamps and stop lamps. Standard No. 108 generally does not prohibit lamp clusters from performing multiple functions. This system is permissible as long as ABC and DEF will serve the respective turn signal functions. All lamps would serve as hazard warning signal lamps and stop lamps. Standard No.108 generally does not prohibit lamp clusters from performing multiple function. This system is permissible as long a ABC and DEF meet all Standard No. 108's requirements for turn, hazard warning, and stop signals when tested in those modes. Your diagram, however, does not indicate which, if any, of these lamps provide the taillamp functions that Standard No. 108 also requires for the rear of motor vehicles. Therefore, lamps ABC and DEF would have to meet the taillamp requirements as well.; >>>2. The second system differs from the first in that the hazar warning system would not operate through the two most outboard lamps. This system is permissible, as Standard No. 108 does not mandate use of all turn signal lamps for the hazard warning signal mode, requiring only 'at least one' on each side of the vehicle, front and rear.; >>>3. The third system differs from the second in that the two mos outboard lamps would no longer be part of the stop lamp system. We view this arrangement as permissible. Standard No. 108 requires that stop lamps, turn signal lamps, and taillamps be located 'as far apart as practicable'. In a literal sense this would appear to require stacking the lamps vertically at the outboard edges of the vehicle, but NHTSA has not adopted a design-restrictive interpretation of this requirement. The determination of practicability is initially that of the manufacturer, but it is subject to review and comment by this agency in instances where such a determination appears clearly erroneous. Where the turn signal system (or part of it) is located at the outboard edges of the vehicle, and the stop lamps and taillamps are adjacent to it, or to each other, we view the 'practicability' requirement as met.; >>>4. The fourth system differs from the third in that the stop lam system would be either that of the systems discussed in items 2 and 3 above, and operating according to Section 3 of your letter. Either system would be acceptable, subject to the operational restriction with turn signal lamps that I shall discuss in my response to section 3.; Next, you have presented four kinds of flashing arrangements for th turn signal lamps. You ask (a) which could meet Standard No. 108, and (b) which could meet Standard No. 108 assuming a flash cycle of 104 seconds. With respect to (a), all four would appear to be acceptable. The standard allows multiple turn signal lamps either to flash simultaneously, or sequentially in the direction of the turn. With respect to (b), Standard No. 108 specifies that a turn signal flasher provide not less than 60 and not more than 120 cycles per minute. This translates to not less than 1 and not more than 2 cycles per second. This requirement would have to be met by all lamps in arrangement (d), i.e. where all lamps operate simultaneously. When operating sequentially, each lamp individually would be subject to the restrictions with the result that the inclusive cycle for a three lamp system would be not less than 3 seconds and not more than 6 seconds. Therefore, arrangements (a), (b), and (c) would meet this requirement assuming a flash cycle of 4 seconds, by arrangement (d) would not, being restricted to a cycle of 2 seconds maximum.; In your third question, or Section 3 as you term it, you have combine the condition of your first two questions and attached a table of 'detailed operating states' of the rear lamps, which incorporated three attached figures, with the question whether it would comply with Standard No. 108. Two of the Operating States illustrated denote the stop lamp 'on' and, individually, the right or left turn signal as 'on'. Standard No. 108 does not allow simultaneous activation of the stop lamp and turn signal lamp when the stop signal is optically combined with the turn signal. In that event, the circuit must be such that the stop signal cannot be turned on in the turn signal which is flashing (paragraph 4.2, SAE Standard J586c *Stop Lamps*, August 1970, incorporated by reference in Standard No. 108). Our other comment concerns 'Fig. a', 'Fig. b', and 'Fig. c' depicting flash cycles of the turn signal lamps. As we noted earlier, the individual lamps are subject to the cycle minima and maxima of 1 to 2 cycles per second, and none of the rates depicted in the three Figures appears to meet the minimum requirement of 1 second. Otherwise, the 'Operating State' table appears acceptable.; I hope that this answers your questions. Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam1507OpenMr. B. D. Sibley, Chief Product Engineer, Certain-Teed Products Corporation, P.O. Box 366, Lawrence, KS 66044; Mr. B. D. Sibley Chief Product Engineer Certain-Teed Products Corporation P.O. Box 366 Lawrence KS 66044; Dear Mr. Sibley: This responds to your April 5, 1974, question whether S5.6.1 or S5.6. of Standard No. 121, *Air brake systems*, requires parking brakes on all axles other than front steerable axles.; S5.6.1 requires 'parking brakes on an axle other than a steerable fron axle' to have certain static retardation force values. 'An axle' refers to any axle other than steerable front axles and therefore S5.6.1 requires parking brakes on all axles other than steerable front axles. A tandem axle consists of two separate axles for purposes of this requirement.; S5.6.2 has no specific axle-by-axle requirements. Its performanc standard may be met by any means which hold the vehicle stationary and conform to S5.6.3 and S5.6.4. It should be emphasized that this requirement cannot be met simply by equipping the vehicle with parking brakes which hold to the limit of tractive ability but permit vehicle movement.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam4705OpenMr. Cadwallader Jones President Jones Ford Inc. P.O.Box 10267 North Charleston, SC 29411; Mr. Cadwallader Jones President Jones Ford Inc. P.O.Box 10267 North Charleston SC 29411; "Dear Mr. Jones: This is in response to your letter to NHTSA in whic you asked questions concerning the circumstances in which Ford vans with more than ten designated seating positions would be considered school buses for purposes of the Federal Motor Vehicle Safety Standards (FMVSS). I apologize for the delay in this response. Your letter asked whether the vans that you describe would be considered school buses if used to transport adult education students, college students, high school students (including athletic teams), playground teams with no connection to schools, day care center clients, or children transported by churches that do not have day schools, but occasionally transport children. The starting point for the agency's analysis of when vehicles used in these circumstances would be required to comply with FMVSS requirements applicable to school buses is Section 102(14) of the National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1391(14)). That provision defines 'Schoolbus' as a 'passenger motor vehicle which is designed to carry more than 10 passengers in addition to the driver, and which the Secretary determines is likely to be significantly used for the purpose of transporting primary, preprimary, or secondary school students to or from such schools or events related to such schools.' When interpreting this provision, the agency has always looked to the nature of the particular institution purchasing the buses. If its central purpose is the education of primary, preprimary or secondary students, the agency has determined that the buses purchased must comply with the FMVSS requirements for school buses. If the institution is concerned primarily with the education of post-secondary students, or serves a function that is custodial rather than educational, NHTSA has said that the buses need not comply with the school bus requirements. The agency has already explained the application of this provision to several of the circumstances raised in your letter. On July 12, 1977, in a letter to Mr. Jim Thomason, the agency said that buses used to transport adults and other post-high school students to vocational training need not comply with the FMVSS school bus requirements because these passengers do not fall in the categories of 'primary, preprimary or secondary students.' However, that interpretation also noted that a bus used by a vocational school connected with a secondary school would fall within the scope of the school bus requirements. The agency has also determined, in a March 17, 1976 letter to Mr. W.G. Milby (and reaffirmed several times since then), that buses used to transport college students need not comply with the standards for school buses. The same letter also includes our opinion that a bus used to transport school athletic teams to activities falls within the scope of the definition of school bus, and must comply with the applicable FMVSS. A May 10, 1982 interpretation letter to Mr. Martin Chauvin determined that vehicles used to transport children to day care centers need not comply with the school bus standards. The rationale for this decision is based on the fact that these facilities serve an essentially custodial function, although they may have some educational components, and are not considered to be schools. Your letter also asks about transportation of children by churches which do not operate day schools. In a November 20, 1978 letter to Mr. J. Perry Robinson, this office determined that the term 'school' does not include church schools such as Sunday schools, or those providing other religious training. As noted in that letter, however, a normal preprimary, primary or secondary school operated under the auspices of a church would be required to comply with the the school bus requirements. Finally, your letter asks whether vehicles used to transport 'playground teams' with no connection to a school would be required to comply with the school bus requirements. The agency has not addressed this question in any past interpretations. However, it is my opinion that a bus used to transport 'playground teams' that are organized independently of any school or educational organization would not be required to comply with the school bus standards. The term 'school' cannot be construed to include athletic teams not connected with any school or educational organization. I hope you have found this information helpful. If you have any further questions, please contact David Greenburg of this office at (202) 366-2992. Sincerely, Stephen P. Wood Acting Chief Counsel"; |
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ID: aiam2002OpenMr. Russell O. Lightcap, Chief, Office of Equipment, Department of Transportation, P.O. Box 9067, Sacramento, CA 95816; Mr. Russell O. Lightcap Chief Office of Equipment Department of Transportation P.O. Box 9067 Sacramento CA 95816; Dear Mr. Lightcap: This responds to your letter of June 12, 1975, requesting confirmatio that you as a final-stage manufacturer would only have to check the application and release times of a truck whose chassis you shortened or lengthened in order to certify that vehicle to the requirements of Federal motor vehicle safety standard (FMVSS) No. 121, *Air Brake Systems*.; Certification of vehicles to the standard is an area which ou statutory scheme leaves to the manufacturers, and in which, aside from discussion of general principles, the agency has declined to issue statements of approval.; The National Highway Traffic Safety Administration has stated tha actual road tests by final stage manufacturers are not necessary to establish compliance with Standard No. 121 or other standards, where other reasonable means, such as engineering calculations coupled with laboratory tests, can be used to the same effect. The agency has recognized that small organizations cannot be expected to test to the same scale or by the same methods as the large integrated automotive manufacturers. Supplier warranties and instructions are one of the primary means by which smaller assemblers are expected to use statutory 'due care' to see that their products conform.; From this discussion it should be apparent that verifying only th brake actuation and release functions will probably be an insufficient basis for certifying that the vehicle will comply, for example, with the stopping distance requirements of the standard. Engineering calculations may, however, satisfy you, in the exercise of due care, that the vehicle as modified meets all the requirements of the standard.; The incomplete vehicle documentation provided with the vehicle woul generally serve as the basis of certification to equipment requirements, to the degree that the equipment is undisturbed. The addition of an axle may cause the air reservoirs to no longer satisfy the air volume requirements of the standard.; Sincerely, Frank Berndt, Acting Chief Counsel |
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ID: aiam5397OpenMr. Thomas D. Turner Manager, Engineering Services Blue Bird Body Company P.O. Box 937 Fort Valley, GA 31030; Mr. Thomas D. Turner Manager Engineering Services Blue Bird Body Company P.O. Box 937 Fort Valley GA 31030; Dear Mr. Turner: This responds to your petition for rulemaking date May 31, 1994. Your petition concerns the following requirement in S5.3.3.2 of Standard No. 217, Bus Emergency Exits and Window Retention and Release: In the case of windows with one release mechanism, the mechanism shall require two force applications to open. A similar requirement is included in S5.3.3.3 for emergency roof exits. Your petition states: The requirement for two force applications to open a single release mechanism is new and unproven and in our opinion is not in the best interest of safety. NHTSA agrees that the sentence in question is susceptible to the reading you gave it. So read, this sentence imposes a requirement not intended by the agency. To avoid such unintended readings, the agency should have worded the sentence as follows: In the case of windows with one release mechanism, the exit shall require two force applications to open. The agency will issue a corrective notice in the future to make this change. Until the notice is issued, we will not take enforcement action against a manufacturer so long as a window or roof exit with one release mechanism requires two force applications to open the exit. I hope you find this information helpful. If you have any other questions, please contact Mary Versailles of my staff at this address or by phone at (202) 366-2992. Sincerely, John Womack Acting Chief Counsel; |
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ID: aiam2452OpenMr. W. G. Milby, Manager, Engineering Services, Blue Bird Body Company, P.O. Box 937, Fort Valley, GA 31030; Mr. W. G. Milby Manager Engineering Services Blue Bird Body Company P.O. Box 937 Fort Valley GA 31030; Dear Mr. Milby: This is in response to your letter of November 3, 1976, in which yo ask whether the label Emergency Door' when placed on the glass near the top of a school bus emergency exit, complies with the requirements of Standard No. 217, *Bus Window Retention and Release*.; The positioning of this label will be regulated by S5.5.3 of Standar No. 217 in the case of school buses manufactured on or after April 1, 1977. That section, as it pertains to the location of the designation Emergency Door,' states in part that the designation shall be ...located at the top of or directly above the emergency exit...' The markings you describe, located at the top of the glass of the emergency door, would appear to be in compliance with the location requirements of S5.5.3 of Standard No. 217 (effective April 1, 1977).; Sincerely, Frank A. Berndt, Acting Chief Counsel |
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ID: aiam0195OpenMr. Edward P. Robinson, Alba Tire Company, 422 Lead Avenue, Southwest, Albuquerque, New Mexico 87101; Mr. Edward P. Robinson Alba Tire Company 422 Lead Avenue Southwest Albuquerque New Mexico 87101; Dear Mr. Robinson: #Thank you for your letter of November 24, 1969, t the National Highway Safety Bureau, concerning our proposed retreaded tire standard. #I appreciate you sending your thoughts on tire safety to our attention since we make a point of being as familiar as possible with the present state-of-the-art of all aspects to tire safety. #The Federal Motor Vehicle Safety Standards do not apply to tires manufactured exclusively for off-road competitive use or to tires retreaded exclusively for off-road competitive use. You are cautioned however, that if the tires are sold for 'street use', then these racing tires will be covered by the proposed standards and would be subject to the requirements. #Sincerely, Charles A. Baker, Office of Standards on Accident Avoidance, Motor Vehicle Safety Performance Service; |
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ID: aiam2901OpenMr. William Shapiro, Manager, Regulatory Affairs, Product Planning and Development, Volvo of America Corporation, Rockleigh, NJ 07647; Mr. William Shapiro Manager Regulatory Affairs Product Planning and Development Volvo of America Corporation Rockleigh NJ 07647; Dear Mr. Shapiro:#This is in response to your letter of September 20 1978, requesting an interpretation of Federal Motor Vehicle Safety Standard No. 101-80, *Controls and Displays*.#Specifically, you asked whether the km/h label on Volvo speedometers could appear in upper case letters instead of the lower case letters appearing in Table 2 of the standard. The answer is yes.#Section 5.2.3 of the standard provides that 'any such display for which no symbol is provided in Table 2 shall be identified by the word or abbreviation shown in column 3.' There is no requirement that the identifying words or abbreviations be in the same type face, type size, or case as those printed in the Federal Register. Therefore, as long as the abbreviations are the same as those appearing in Table 2 and are visible, no problem arises because Volvo wishes to use upper case, rather than lower case letters.#Sincerely, Joseph J. Levin, Jr., Chief Counsel; |
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ID: aiam3613OpenMr. James R. Bede, President, Bede Design Inc., 901 E. Orchard Street, Mundelein, IL 60060; Mr. James R. Bede President Bede Design Inc. 901 E. Orchard Street Mundelein IL 60060; Dear Mr. Bede: This is in reply to your letter of September 29, 1982, asking for a interpretation that your modified motorcycle is a 'motorcycle' under the Federal Motor Vehicle Safety Standards. In addition to the standard motorcycle configuration of a single front and rear wheel, your design incorporates two small wheels in outrider positions, both of which hold the vehicle at rest, but which, in motion, do not touch the ground simultaneously. The purpose of the wheels is to add stability so that in a left turn the left outrider wheel will touch the ground, and in a right turn, the right wheel.; This configuration appears to meet the definition of 'motorcycle contained in 49 CFR 571.3(b) as a machine 'designed to travel on not more than three wheels in contact with the ground.' Although the vehicle rests on four wheels, it travels on only two or three depending upon whether it is proceeding in a straight direction or in a turn.; We appreciate your interest in motorcycle safety. Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam3243OpenMr. Don Gerkin, Product Engineer, Cosco Home Products, 2525 State Street, Columbus, IN 47201; Mr. Don Gerkin Product Engineer Cosco Home Products 2525 State Street Columbus IN 47201; Dear Mr. Gerkin: This responds to your letter of January 23, 1980, to Mr. Vladisla Radovich concerning Standard No 213, *Child Restraint Systems*. Your letter was forwarded to my office for reply.; You asked whether a crotch strap that is 'permanently attached to movable shield can be attached during the 20 mph test required for child restraint systems that have fixed or movable shields (sic). Sections S6.1.2.3.1(c) and S6.1.2.3.2(b) provide that, in the 20 mph tests, the child restraint belts are not to be attached unless 'they are an integral part of the fixed or movable shield.' The agency used the word 'integral' in its ordinary sense to mean something that is 'formed as a unit with another part.' (Webster's New Collegiate Dictionary, 1977). A crotch strap that is permanently affixed to the shield is formed as a unit with the shield, and therefore, can remain attached during the test.; You also asked, whether, if the movable shield 'were designed in such way that moving it into position for use it automatically locked in that position, and a child was unable to unlock it', would the 20 mph test be conducted with the shield locked into place? Sections S6.1.2.3.1(c) and S6.1.2.3.2(b) provide that each movable surface is to be positioned in accordance with the manufacturer's instructions. Therefore, as long as your instructions explain how to lock the movable shield, it can be locked into place prior to the testing.; If you have any further questions, please let me know. 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.