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: aiam4393OpenMr. Thomas L. Long, Vice-President R & D, Think, Inc., P.O. Box 414, Smyrna, TN 37167; Mr. Thomas L. Long Vice-President R & D Think Inc. P.O. Box 414 Smyrna TN 37167; Dear Mr. Long: This is in reply to your letter of August 20, 1987, to Taylor Vinson o this office. You have enclosed a decal intended to be affixed 'on the outside of the rear window of an automobile, directly in front of the high mounted stop light. You have asked about the relationship of the decal to Federal Motor Vehicle Safety Standard No. 108.; Center highmounted stoplamps are required to be designed so that ligh output (candela) may be measured at 13 individual test points, at a distance of not less than 10 feet. With the decal applied to the rear window, it is possible that the requisite minimum or maximum candela specified by Standard No. 108 could not be met at all of the test points. Further, the effective luminous area of the lamp must be not less than 4 1/2 square inches. And while the decal would not be applied to the lens, nevertheless, the lens area when viewed from behind could be effectively reduced. Because a vehicle must meet Standard No. 108 at the time of its initial sale, the vehicle could be delivered to its purchaser with the decal attached only if the vehicle continued to meet the light output and effective luminous area requirements.; Even if a vehicle could not be delivered with the decal attached nothing in Standard No. 108 or the National Traffic and Motor Vehicle Safety Act prohibits a vehicle owner from applying the decal to his own vehicle, or from taking any other action that might affect the compliance of his vehicle with any of the Federal motor vehicle safety standards. The Act does forbid other persons from such actions, so that after a vehicle is sold, the dealer (or a motor vehicle repair business) could still be prohibited from applying the decal. Regulation of a vehicle in use is a matter of the laws of the States where vehicles are registered and operated. Even though Federal law does not prohibit an owner from applying the decal, a State law might. For advice of State laws, you should write the American Association of Motor Vehicle Administrators, 1201 Connecticut Ave. N.W., Washington, D.C. 20036.; Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam1988OpenMr. W.J. Joyce, Jr.,Consultant, International Business,Grosse Pointe Plaza Bldg.,22725 Mack Avenue,St. Clair Shores, Michigan 48080; Mr. W.J. Joyce Jr. Consultant International Business Grosse Pointe Plaza Bldg. 22725 Mack Avenue St. Clair Shores Michigan 48080; Dear Mr. Joyce:#This responds to your June 18, 1975, question whethe S5.3 of Standard No. 105-75, *Hydraulic Brake Systems*, requires that the brake fluid level warning system specified by S5.3.1 be instantaneous when the brake fluid level reaches the condition described in S5.3.1(b).#The answer to your question if no. The National Highway Traffic Safety Administration recognizes that a minimal interval between the occurrence of the specified condition and the appearance of the required signal is a physical fact. I enclose a copy of an interpretation of a similar require- ment of Standard No. 105-75 for your information. In the case of the brake fluid level indicator, a time interval that is insignificant with respect to the time required to respond to the signal would be permissible.#Sincerely,Frank A. Berndt,Acting Chief Counsel; |
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ID: aiam4404OpenMr. M.B. Mathieson, Director of Engineering, Thomas Built Buses L.P., P.O. Box 2450, High Point, NC 27261; Mr. M.B. Mathieson Director of Engineering Thomas Built Buses L.P. P.O. Box 2450 High Point NC 27261; Dear Mr. Mathieson: This is in reply to your letter of April 27, 1987, asking for clarification of my letter of March 20.; In that letter I answered your question as to whether the results o frontal barrier impact tests that occurred at 30.4 mph with a vehicle that exceeded the test weight limits would constitute either a noncompliance with Standard No. 301 or a safety related defect. Because the test was not conducted in accordance with Standard No. 301's conditions I replied that this would not be a noncompliance, and further, that those results 'do not constitute a safety related defect regardless of the use of the vehicle.' This statement appears unclear to you.; By my earlier statement I intended to explain that we do not use safety standard's compliance test results (particulary if the test was not conducted in accordance with the prescribed procedures) as the sole basis for a determination of a safety-related defect in the same aspect of performance governed by that standard. For example, having determined through rulemaking that a particular level of vehicle performance is expected in a 30 mph crash test, it would be inappropriate to use the results from an otherwise identical crash test conducted at 35 mph to form the sole basis for a determination of a safety-related defect in the tested vehicles. To do so would constitute, in effect, rulemaking to raise the impact speed in the standard to 35 mph. We completely agree, however, with your statement that 'there can be safety- related defects that are not addressed by the standards.' We also agree that the manufacturer has the responsibility to address safety defects that become apparent to him through test data or otherwise.; With this background, we will turn to your question. You have now pose a hypothetical in which your tests indicate that a fully-loaded school bus may encounter a severe leakage exceeding 4.1 ounces of fuel per minute in a head-on impact of 30 m.p.h. This may be evidence that could lead you to believe that there would be a significant number of failures if a school bus, in its normal operation with full complement of students, encounters a head-on collision at what appears to be a reasonable operating speed. This combination of factors might appear to pose an unreasonable risk to safety and afford the basis for the determination that a safety related defect exists.; Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam1251OpenMr. James Tydings, Chief Engineer, Thomas Built Buses, Inc., 1408 Courtesy Road, P.O. 1849, High Point, NC 27261; Mr. James Tydings Chief Engineer Thomas Built Buses Inc. 1408 Courtesy Road P.O. 1849 High Point NC 27261; Dear Mr. Tydings: This is in reply to your letters of July 26 and August 7, 1973 requesting an opinion on the applicability of the emergency exit provisions (S5.3 to S5.5) of Motor Vehicle Safety Standard No.217, Bus Window Retention and Release (49 CFR 571.217), to buses that are of the same design as school buses, but which are not manufactuerd (sic) (they are not painted yellow, nor do they have warning devices) nor used as school buses. You ask further that the standard exempt prison buses.; We interpret the exemption for school buses to include buses similarl designed, without regard to their intended use. School bus is defined in 49 CFR 571.3 to mean,; a bus *designed* primarily to carry children to and from school....' We are of the opinion that buses which share the same design as buse that clearly fall within the definition of school bus' are school buses under Standard No. 217, and are therefore exempt from the emergency exit provisions of the standard. No modification of the standard is accordingly called for.; With respect to your request regarding prison buses, we are presentl considering similar requests previously received, and plan to respond by notice published in the *Federal Register* in the near future.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam4270OpenMr. Hal McNamara, McNamara Pontiac Inc., P. O. Box 3269, Orlando, FL 32802; Mr. Hal McNamara McNamara Pontiac Inc. P. O. Box 3269 Orlando FL 32802; This is in reply to your letter of September 29, 1986, to Mr. Vinson o this Office asking for an interpretation of Motor Vehicle Safety Standard No. 108. You have enclosed a copy of a flyer for 'Ad-A-Lens,' the device appears to be an overlay with a dealer's name, intended to be placed over the lens of the center highmounted stop lamp. You have told us that 'the company selling this product says there is no problem legally or safety-wise....' You have also furnished us with a portion of a preamble to the standard discussing the visibility requirements for the lamp in which the statement is made that beyond the specified test points 'no requirements are established other than that the signal be 'visible,' which means any portion of the signal, without regard to lens area or candela.'; Standard No. 108 does not prohibit adding an overlay to the cente highmounted stop lamp that contains a dealer's name. However, the addition of the overlay must not create a noncompliance with Standard No. 108, in violation of the National Traffic and Motor Vehicle Safety Act.; Paragraph S4.1.141(a) requires each center highmounted stop lamp t have an effective projected luminous area not less than 4 1/2 square inches. Application of dealer identification to an original equipment lamp not designed for the overlay could well reduce the luminous area below the minimum required by the standard. Further, there is the possibility that the overlay could affect photometric compliance as well. The lamp must meet the photometric requirements at the 13 test points specified in Standard No. 108 up to the maximum specified 10 degrees right and left. Beyond 10 degrees, up to 45 degrees right and left, the overlay must not obscure the signal so that no portion of it is visible.; Should the overlay create a noncompliance with Standard No. 108, an person offering for sale or selling a vehicle with it would be in violation of the National Traffic and Motor Vehicle Safety Act, as would any dealer adding an overlay to the lamp of a vehicle after it is sold. The Act provides that a penalty of up to $1000 per violation may be imposed, up to a maximum of $800,000 for any related series of violations. You should also seek the advice of State motor vehicle authorities on this matter.; We are providing a copy of this interpretation to Ad-A-Lens, an appreciate your bringing this matter to our attention.; Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam4032OpenMr. Ron Marion, Specification Engineer, Thomas Built Buses, Inc., P.O. Box 2450, 1408 Courtesy Road, High Point, NC 27261; Mr. Ron Marion Specification Engineer Thomas Built Buses Inc. P.O. Box 2450 1408 Courtesy Road High Point NC 27261; Dear Mr. Marion: This responds to your October 1, 1985 letter to this office askin whether each state has the discretion to determine whether vehicles purchased for Head Start programs should be school buses. While the memorandum you intended to enclose from Commission Hodges was excluded from your letter, we are able to answer your questions directly.; Your first question asked, 'Are Head Start Programs considered school or school related events for preprimary students?' This agency has consistently stated that a Head Start facility is considered a preprimary school for the purpose of the National Traffic and Motor Vehicle Safety Act.; Your second question asked, 'Are Head Start Agencies required t provide school buses when transporting 10 or more students?'; As you know, the requirements under the Vehicle Safety Act apply to th manufacture and sale of new motor vehicles, and not to motor vehicle use. The Vehicle Safety Act does not require schools to *use* school buses that comply with our motor vehicle safety standards for school buses. Instead, given that Head Start facilities are 'schools' within the meaning of the Vehicle Safety Act, each person selling a new bus (i.e., a motor vehicle designed to carry more than 10 persons) to such a facility is required to sell a bus that complies with NHTSA's school bus safety standards.; Your final question asked about state discretion to determine whethe Head Start centers must provide complying school buses.; The requirements governing the *use* of a motor vehicle after it i sold is a matter of state law. While NHTSA has issued recommendations to the states regarding school bus operation in Highway Safety Program Standard No. 17, *Pupil Transportation Safety* (copy enclosed), this agency has no requirement that Head Start centers must use complying school buses. On the other hand, the responsibility of school bus sellers to comply with the requirements of the Vehicle Safety Act, and to sell a vehicle that complies with all applicable safety standards, including the school bus safety standards, is a Federal requirement. Accordingly, the states have no discretion to permit persons to sell new buses to Head Start centers if those buses do not comply with the motor vehicle safety standards for school buses.; For your future reference, Mr. Tilton is no longer with this agency. I you have further questions, please do not hesitate to contact us.; Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam0381OpenMr. Louis L. Allen, President, Chase Manhattan Capital Corporation, 1 Chase Manhattan Plaza, New York, NY 10005; Mr. Louis L. Allen President Chase Manhattan Capital Corporation 1 Chase Manhattan Plaza New York NY 10005; Dear Mr. Allen: This is in reply to your letter of June 21, 1971 concerning the Tir Identification and Record Keeping regulation (49 CFR Part 574). We are concerned with the points you raise in your letter regarding the confidentiality of tire dealers customer's lists and the extra burden the regulation causes dealers who handle more than one brand of tires.; However, under the National Traffic and Motor Vehicle Safety Act we d not feel we have authority to require the tire manufacturer to choose someone as his designee. Section 113(f) of the Act makes the tire manufacturer responsible for maintaining the records of first purchasers.; As you probably know, any use of the customer's list by the tir manufacturer is expressly prohibited by the regulation. Any violation of this prohibition will be enforced.; I have enclosed for your information a copy of a notice published i the *Federal Register* May 28, 1971 which is relevant to the points you raise.; Thank you for your comments and interest in auto safety. Sincerely, Lawrence R. Schneider, Acting Chief Counsel |
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ID: aiam2861OpenMr. James Tydings, Specifications Engineer, Thomas Built Buses, Inc., 1408 Courtesy Road, P.O. Box 2450, High Point, NC 27261; Mr. James Tydings Specifications Engineer Thomas Built Buses Inc. 1408 Courtesy Road P.O. Box 2450 High Point NC 27261; Dear Mr. Tydings: This responds to your August 21, 1978, letter asking whether you ar permitted under Standard No. 217, to place the emergency exit sign at the bottom of a rear emergency window exit.; The National Highway Traffic Safety Administration has permitted th use of the emergency exit sign to be on the top half of rear emergency doors. This has permitted the sign to be located just below the glass on the rear emergency door. Although your location of the exit sign is not on the top of the rear emergency window exit, its location is similar to the location of the exit sign on a rear emergency door. Since the location of the sign is on the emergency window exit and is within the top half of the bus, the agency has determined that this location complies with the requirement.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam5545OpenMr. Stephen M. Padula Industry Standards and Government Regulations Uniroyal Goodrich Tire Company P.O. Box 2501 Greenville, SC 29602; Mr. Stephen M. Padula Industry Standards and Government Regulations Uniroyal Goodrich Tire Company P.O. Box 2501 Greenville SC 29602; "Dear Mr. Padula: This responds to your letter of March 21, 1995, i which you asked whether it is permissible to have a treadwear grade of 00 or 000 on tires under the Uniform Tire Quality Grading Standards (UTQGS), 49 CFR 575.104. The answer to your question is yes. As you know, the UTQGS currently provide that all new passenger car tires sold in the United States must be graded by their manufacturers or brand name owners for treadwear, traction, and temperature resistance. The grades must be assessed in accordance with paragraphs (d)(1)(i)(A) and (B) of the UTQGS and must be molded into or onto the tire sidewall. Paragraph (d)(2)(i) requires the treadwear grade to be expressed as 2 or 3 digits, representing the percentage (P) of the NHTSA nominal treadwear value, computed as follows: Projected P = mileage x 100 30,000 The percentage derived from the above formula is then rounded off to the nearest lower 20-point increment to arrive at the treadwear grade. In your letter you proposed a hypothetical example of a tire with a projected mileage of 5,000 miles, which would compute as follows: P = 5,000 x 100 = 16.67 30,000 Rounded off to the nearest lower 20-point increment, the treadwear rating for that tire would be 00 or 000. Your example would be correct, if tires still exist that have a projected tread life of 5,000 miles. Although NHTSA has not found any tires so rated, under the current provisions of the UTQGS, it is possible, as demonstrated by your example, to have a UTQGS treadwear rating of 00 or 000. I hope this information is helpful to you. Should you have any questions or need 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: aiam3308OpenMr. James Tydings, Specifications Engineer, Thomas Built Buses, 1408 Courtesy Road, P.O. Box 2450, High Point, North Carolina 27261; Mr. James Tydings Specifications Engineer Thomas Built Buses 1408 Courtesy Road P.O. Box 2450 High Point North Carolina 27261; Dear Mr. Tydings: This is in response to your letter of April 28, 1980, concernin Standard No. 111, *Rearview Mirrors*. Your letter refers to section 9.1 of the standard, but the question themselves are concerned with section 9.2 of the standard.; You asked whether the standard requires the use of mote than on outside crossview convex mirror on a schoolbus. Section 9.2 provides, in part, 'Each schoolbus, except those that are forward control vehicles, shall have a convex mirror...' The use of the singular noun 'mirror' means that only one convex mirror can be used to meet the requirements of section 9.2.; You also asked the agency to define the word, 'view' as that word i used in the portion of section 9.2 that requires the outside crossview convex mirror to be 'mounted so as to provide the driver a view of the front bumper...' As explained in the notice proposing the use of crossview mirrors, the purpose of the requirement is to 'address special problems of driver visibility associated with pupil transportation.' The agency explained that 'to reduce the danger of death or injury to school children it is necessary that the school bus driver have the fullest possible view of all sides of the vehicle, including the front' (40 FR 33829, August 12, 1975). Use of a crossview mirror allows the driver to see the area immediately in front of a stopped bus to be sure there are no children there, before moving the bus.; The agency used the word 'view' in its ordinary, dictionary sense t mean within the range of sight. Thus, most, but not literally all, of the front bumper must be visible to the driver by use of the crossview mirror to ensure that he or she can see children standing in front of the bus.; Please note that the agency's November 6, 1978, proposal (43 FR 51657 to upgrade the standard would establish new field of view requirements for the crossview mirror. 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.