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: aiam3531OpenMr. William E. Lawler, Specifications Manager, Indiana Mills & Manufacturing, Inc., 120 West Main Street, Carmel, IN 46032; Mr. William E. Lawler Specifications Manager Indiana Mills & Manufacturing Inc. 120 West Main Street Carmel IN 46032; Dear Mr. Lawler: This responds to your recent letter requesting an interpretatio concerning paragraph S4.3(c)(1) of Safety Standard No. 209, *Seat Belt Assemblies*. You ask for clarification of the cases in which a 5,000-pound attachment bolt may be used in lieu of a 9,000-pound bolt.; Paragraph S4.3(c)(1) of Standard No. 209 specifies that attachmen bolts used to secure the pelvic restraint of a seat belt assembly to a motor vehicle shall withstand a force of 9,000 pounds, except that 'attachment bolts of a seat belt assembly designed for installation in specific models of motor vehicles in which the ends of two or more seat belt assemblies cannot be attached to the vehicle by a single bolt shall have a breaking strength of not less than 5,000 pounds.' The intent of the requirement in S4.3(c)(1) is to assure that inadequate attachment bolts will not be used to attach seat belt assemblies to a vehicle. A 5,000- pound bolt may be used only if the belt assembly is designed for use in specific models of vehicles in which only one end of a belt assembly can be attached by a single bolt.; In answer to your question, the agency does not 'have in mind' certai brands or models of vehicles which would qualify under this exception, and the exception is not limited to single-seat vehicles. Further, the requirement does not mean that a seat belt assembly that can be used in more than one application must be installed with a 9,000-pound bolt. If a particular assembly is designed for use in several different models in all of which only one end of the belt assembly can be attached by a single bolt, then a 5,000- pound bolt is sufficient. The distinction is that an aftermarket belt for universal application must be accompanied with a 9,000- pound bolt, because in some vehicle models it would be possible to mount two ends of seat belt assemblies with a single bolt.; You should note that paragraph S4.1(k) of Standard No. 209 requires th manufacturer of seat belt assemblies for after-market use to furnish an instruction sheet stating whether the assembly is for universal installation or for installation only in specifically stated motor vehicles. If you provide 5,000-pound bolts for any of your assemblies, the instruction sheet required by S4.1(k) should specify that the assemblies are to be used only in the vehicle models you list.; I hope this has answered all your questions. Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam3161OpenMr. R. Birch, Chief Constable, P.O. Box 4, Leek Wootton, Warwick, England, CV35 8QB; Mr. R. Birch Chief Constable P.O. Box 4 Leek Wootton Warwick England CV35 8QB; Dear Mr. Birch: This responds to your recent letter concerning a reflective film tha is being applied to the windows of some vehicles in the United Kingdom. You ask whether regulations preventing the use of such film have been introduced in the United States.; At the current time, there are no Federal regulations that prohibit th use of reflective films such as you describe. The National Highway Traffic Safety Administration issues safety standards and regulations governing the manufacture of new motor vehicles and motor vehicle equipment. We have no authority, however, to regulate the use of motor vehicles, such as an owner applying reflective film to his car. Further, we have issued interpretations stating that reflective coated polyester films do not qualify as glazing materials and, therefore, do not come within the purview of our Safety Standard No. 205. This interpretation referred only to polyester film sold by itself. Glazing materials that have coated films that were applied by the glazing manufacturer are required to comply with the standard, including the light transmittance requirements.; The agency did receive a petition for rulemaking last year from th California Highway Patrol asking that reflective glazing materials be prohibited (glazing coated with reflective substances by the glazing manufacturer). While use of the reflective coating could reduce the ability of a driver to look through the glazing of vehicles in front of him or her and see the road and vehicles ahead, we denied the petition since we lacked data indicating that there is a safety problem created by the coating. If you have or know of any data indicating a safety problem, we would very much appreciate seeing the data. From a law enforcement viewpoint, the problem posed by the reflective coating is apparently more than theoretical, since officers cannot see inside a vehicle with coated glazing to the extent they deem necessary.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam0464OpenMr. Stanley Hamilton, Director, Government and Public Affairs, National Association of Motor Bus Owners, 1025 Connecticut Avenue, N.W., Washington, DC 20036; Mr. Stanley Hamilton Director Government and Public Affairs National Association of Motor Bus Owners 1025 Connecticut Avenue N.W. Washington DC 20036; Dear Mr. Hamilton: This is in reply to your letter of August 2 to which you attached letter from Mr. W. Dershko of Motor Coach Industries concerning the certification regulations that go into effect January 1, 1972. (Perhaps by error, you referred to a letter from Mr. Stieber of Greyhound Lines.) Rulemaking concerning gross axle weight rating and gross vehicle weight rating was in process at the time, hence the reason for our delay.; Mr. Dershko asked whether the gross vehicle weight rating must equa the sum of the gross axle weight ratings. The answer is no. The practice described, of stating a GVWR less than the sum of the GAWR's, will be quite proper under the new regulations.; Mr. Dershko also said that he was concerned as to how to interpret th definition of gross axle weight rating, and that 'several factors to consider are the tire capacities, axle assembly capacity, and the coach frame structure capacity.' We agree that all those factors must be considered. The manufacturer must set his gross axle weight ratings in view of the weakest elements in the load-bearing systems of the vehicle.; Let us know if we can be of further assistance. Sincerely, Lawrence R. Schneider, Acting Chief Counsel |
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ID: aiam2459OpenMr. Karl-Heinz Ziwica, Manager - Safety Engineering, BMW of North America, Inc., Montvale, NJ 07645; Mr. Karl-Heinz Ziwica Manager - Safety Engineering BMW of North America Inc. Montvale NJ 07645; Dear Mr. Ziwica: THis is in response to your October 29, 1976, request for confirmatio that a recent NHTSA interpretation regarding the buckle crush requirements of Standard No. 209 (as stated in a letter to Volvo dated August 31, 1976) is applicable to BMW seat belt buckles.; Our letter to Volvo stated that the existing S4.3(d)(3) buckl requirements are not applicable to buckles that are located between bucket seats and attached to the console or to the end of a rigid cable or bar.' This interpretation constitutes an explanation of S4.3(d)(3) as its provisions apply to all seat belt buckles regulated by the standard. The interpretation is not applicable only to Volvo belt buckles or to buckles produced by any other individual manufacturer. It is the responsibility of each manufacturer to determine, in the first instance, whether or not his products fall within any standard's provisions, including provisions that are explained by means of an interpretation.; I am enclosing a copy of our August 31, 1976, letter to Volvo for you information. As requested, we have withdrawn your petition for rulemaking.; Sincerely, Frank A. Berndt, Acting Chief Counsel |
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ID: aiam4974OpenRobert S. McLean, Esq. King & Spalding 191 Peachtree Street Atlanta, GA 30303-1763; Robert S. McLean Esq. King & Spalding 191 Peachtree Street Atlanta GA 30303-1763; "Dear Mr. McLean: This responds to your March 9, 1992 letter, seekin an interpretation of Standards No. 208, Occupant Crash Protection and No. 209, Seat Belt Assemblies (49 CFR 571.208 and 571.209, respectively). More specifically, you were interested in how certain provisions of these standards apply to a seating position equipped with an automatic shoulder belt certified as complying with the occupant protection requirements of Standard No. 208 and a separate manual lap belt. Your letter indicated you were particularly interested in whether the automatic belt is considered a Type 2a shoulder belt, as that term is defined in S3 of Standard No. 209, and whether the automatic belt must provide the warning instructions required for Type 2a shoulder belts by S4.1(l) of Standard No. 209. The answer to both these questions is no. NHTSA has consistently recognized a distinction between automatic safety belts and the manual safety belts defined in S3 of Standard No. 209 (Type 1, Type 2, and Type 2a belts). The origins and application of this distinction is explained at length in this agency's April 14, 1986 interpretation letter to Mr. David Martin, a copy of which was enclosed in your letter to me. Thus, automatic belts are not treated as Type 1, Type 2, or Type 2a belts for the purposes of Standard No. 209, and are not generally subject to the provisions of Standard No. 209 that apply to each of those types of belts. Since automatic belts are not Type 2a belts, automatic belts are not required to include any warnings required for Type 2a belts. Instead, S4.5.3 of Standard No. 208 defines the term 'automatic belt' and sets forth special provisions for such safety belts. S4.5.3.3 specifies that an automatic belt shall conform to S7.1 of Standard No. 208 (the belt adjustment requirements) and have a single emergency release mechanism, and be equipped with a special warning system in place of the warning system required for manual belts. In addition, S4.5.3.4 specifies that any automatic belts that are not subject to the crash testing requirements for occupant protection under Standard No. 208 must comply with the requirements of S4.2, S4.3, and S4.4 of Standard No. 209 (webbing, attachment hardware, and belt assembly performance requirements, respectively). I hope this information is helpful. If you have any further questions or need some additional information on the requirements applicable to automatic belts, feel free to contact Steve Kratzke of my staff at this address or by telephone at (202) 366-2992. Sincerely, Paul Jackson Rice Chief Counsel"; |
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ID: aiam0034OpenHonorable Bob Wilson, House of Representatives, Washington, DC, 20515; Honorable Bob Wilson House of Representatives Washington DC 20515; Dear Mr. Wilson: This is in response to your letter of August 16 in which you attached letter from your constituent, Mrs. Beverly Hoffman of San Diego. Mrs. Hoffman asked if there is any Federal or state regulation, or city ordinance, which forbids the removal or concealment of passenger seat belts in taxicabs. Mrs. Hoffman has raised an important question and one which is of vital concern to the objectives of the National Traffic and Motor Vehicle Safety Act of 1966: the retention of a (sic) safety equipment in a vehicle after its original purchase.; Since I expect that California law is of most interest to both Mrs Hoffman and you, I will answer her question on the basis of the California Vehicle Code. Since January 1, 1964, Section 27309 has made it an offense to sell in California any new passenger vehicle which does not have at least two state approved restraint belts or harnesses in its front seat. Retention of the front seat belts by the vehicle owner is indirectly required by Section 40001(b)(2) which makes it unlawful for 'an owner to request, cause, or permit the operation of any vehicle which is not *equipped as required in this Code*.' (emphasis supplied) Since California has no annual motor vehicle inspection, enforcement of this law has presumably been by spot inspection. Members of the California Highway Patrol (Section 2804) and city traffic officers (Section 2806) have the authority to inspect a vehicle to determine whether its equipment is in compliance with the Code.; With respect to rear seat belts which most directly concern Mrs Hoffman as a passenger, their installation has not been required by the Code. Such belts as she may have seen in the rear of California taxis have been provided as a courtesy of the owner rather than as a requirement of the law. But, as she correctly notes, all passenger cars including taxicabs manufactured on or after January 1, 1968, must comply with Federal motor vehicle safety standards. One of these, Standard No. 208, will require taxis to be manufactured with lap restraint belts installed in each rear seating position. But if the California legislature has not amended the Vehicle Code itself to require their installation it would appear that there is no legal reason why a cab owner may not remove rear seat belts should he wish to go to the trouble.; Under the Act, the Secretary of Transportation does not have th authority to directly regulate motor vehicles 'after the first purchase of it in good faith for purposes other than resale.' Instead, Congress intended that used vehicles be regulated by periodic state inspection. To implement this intent the Secretary has been directed to study state inspection systems and, in due course, to establish uniform standards applicable to all used motor vehicles. A hypothetical standard--and one which we shall consider--requiring the presence of original equipment safety items at time of each inspection would be sufficient to cover retention of rear seat safety belts. But the Act establishes no requirement that the states or any individual follow any used vehicle standard. For the probably enforcement mechanism of used car standards it is necessary to turn to the companion Highway Safety Act of 1966. Under this Act each state is required to have a highway safety program in accordance with standards promulgated by the Secretary. One such standard, already issued, establishes minimum requirements for periodic motor vehicle inspection. Eventually it is possible that used car standards will be suggested to the states through this motor vehicle inspection standard, but enforcement of the used car standards will be left to the states.; Concerning concealment of the belts, I am aware of no legislation Federal, state, or municipal, which requires that a safety item not only be retained but also available for use. But I believe that sufficient authority may exist in the Highway Safety Act's mandate to the Bureau to include 'vehicle operation' in the highway safety program standards to warrant our serious consideration of it.; I hope that this has answered Mrs. Hoffman's questions and I appreciat her interest in traffic safety.; Sincerely, William Haddon, Jr., M. D., Director |
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ID: aiam2009OpenMr. Hironori Tanaka, Toyoda Gosei Co., Ltd., 9, 1-chome, Nishiyabushitacho, Nishiku, Nagoya, Japan; Mr. Hironori Tanaka Toyoda Gosei Co. Ltd. 9 1-chome Nishiyabushitacho Nishiku Nagoya Japan; Dear Mr. Tanaka: #Please forgive the delay in responding to your lette of April 25, 1975, which questioned our interpretation of March 13, 1975, of the adhesion requirement of S7.3.7 of Federal Motor Vehicle Safety Standard No. 106-74, *Brake Hoses*. #Our interpretation was that the requirement applies to each pair of adjacent layers of a brake hose. Multilayer hose manufacturing in the United States and Europe is in fact made with bonding between all pairs of adjacent layers. There is no change in our interpretation. #Sincerely, Frank A. Berndt, Acting Chief Counsel; |
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ID: aiam5236OpenMr. Richard G. Meier Deputy Assistant Office of the U.S. Trade Representative 600 17th Street, N.W. Washington, DC 20506; Mr. Richard G. Meier Deputy Assistant Office of the U.S. Trade Representative 600 17th Street N.W. Washington DC 20506; Dear Mr. Meier: This letter follows up on the July 23, 1993, meeting i which you and Ms. Suzanne Troje discussed with representatives of this agency concerns of the Mexican Government that tires produced in Mexico for sale in the U.S. must be labeled in English and tested in Texas. We would like to explain our regulations and correct an apparent misimpression of the Mexican government. Tires manufactured for sale in the United States must be labeled with safety and consumer information that is required by statute (the National Traffic and Motor Vehicle Safety Act) and by regulation. The regulations require that the information be in English. There is no available exception to the English labeling requirement for the safety information, but there is an exception to the consumer information requirement of our uniform tire quality grading standards (UTQGS, copy enclosed). The UTQGS do not apply to 'limited production tires,' as defined in that standard. This exception could provide the basis for a Mexican tire manufacturer to import a limited number of tires into this country to assess the market. However, the annual importation of that tire into the U.S. must not exceed 15,000 tires. The UTQGS do not require that manufacturers test their tires at this agency's test track at San Angelo, Texas. Manufacturers may test their tires where they choose, and may even choose not to test their products at all. However, the specification in the UTQGS regulations that testing is done at San Angelo means that NHTSA must use that track in any compliance testing of tires. In order to protect themselves against the possibility that the agency will find a noncompliance based on testing at San Angelo and initiate an enforcement action, it would be prudent for tire manufacturers to base their assigned grades on their own testing at San Angelo or on some substitute means whose results demonstrably correlate with the results of testing at San Angelo. We hope this information is helpful. For your information, I have attached a general information sheet discussing NHTSA's requirements for new manufacturers. Please let us know if we can be of further assistance. Sincerely, John Womack Acting Chief Counsel Enclosure; |
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ID: aiam3248OpenMs. Wendy Garner, Kenworth Truck Co., Box 1000, Kirkland, Washington 98033; Ms. Wendy Garner Kenworth Truck Co. Box 1000 Kirkland Washington 98033; Dear Ms. Garner: This responds to your telephone conversation with Mr. Schwartz of m office in which you asked whether net brake horsepower must be decipherable from the engine type encoded in the vehicle identification number (VIN) of heavy trucks.; The *precise* net brake horsepower of heavy trucks (or any othe vehicle class or type) need not be encoded. This was the point which the agency was making in its March 22, 1979 (44 FR 17489) statement that:; >>>(W)hile net brake horsepower is among the characteristics to b considered in establishing an engine type, there is no requirement that it be encoded in the engine type code. In some instances such as with heavy truck engines, encodement would not be practicable.<<<; However, except as provided below, the *range* of net brake horsepowe must be encoded to differentiate engine types as required by section 4.5.2 of Federal Motor Vehicle Safety Standard 115. To define the acceptable range of net brake horsepower for a single engine type, the agency made a clarifying amendment to that section (February 25, 1980, 45 FR 12257). Footnote 1 to Table I provides that otherwise identical engines having net brake horsepower ratings that vary up to plus or minus 10 percent, may be treated as being of the same engine type.; The exception to the requirement to encode the range of net brak horsepower involves manufacturers which intend to utilize more than 33 engine types whose horsepower ranges fall outside the plus or minus 10 percent parameters. These manufacturers will be unable to encode their current or anticipated engine types utilizing only a singe VIN position since there are 33 separate characters authorized to be used for each VIN position. Consequently, they need not encode net brake horsepower in any way. The agency did not intend that more than one VIN position be used to encode net brake horsepower. Using more than one position would be impracticable at this time given the amount of information that needs to be encoded in the VIN.; Please contact Mr. Schwartz should you(sic) have any further question concerning this subject.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam1275OpenMr. David J. Humphreys, Paulson and Humphreys, 1140 Connecticut Avenue, NW., Washington, DC 20036; Mr. David J. Humphreys Paulson and Humphreys 1140 Connecticut Avenue NW. Washington DC 20036; Dear Mr. Humphreys: This is in reply to your communication of September 20, 1973 requesting our review of a sample owner notification letter, regarding a safety related defect in certain Apache Camping Trailers, for purposes of conformity to 49 CFR Part 577, Defect Notification.; We believe the reference in the first sentence of the second paragraph that a defect *may* exist, to be inconsistent with the regulation. This statement is apparently intended to meet the requirement of Section 577.4(b). This subsection, however, requires a particular statement and does not permit the use of 'may' or similar expression. The statement required is not solely one of fact, but rather one of law, and the opening sentence of Section 577.4(b) shows clearly that the statement is required where the defect potentially exists in the vehicles or equipment in question. We also believe your references in other parts of the letter to 'possible defect' suffer from the same deficiency.; In other respects, we believe your notification letter conforms to Par 577.; Sincerely yours, Lawrence R. Schneider, Chief Counsel |
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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.