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: aiam0346OpenMr. Marvin S. Wright, Transportation and Distribution Department, Boise Cascade Corporation, P.O. Box 7757, Boise, ID 83707; Mr. Marvin S. Wright Transportation and Distribution Department Boise Cascade Corporation P.O. Box 7757 Boise ID 83707; Dear Mr. Wright: This is in reply to your letter of April 29, to Mr. Charles West, o the subject of air brake systems on mobile structure trailers. The standard to which you refer does not require air brakes to be installed on trailers, as your associates seem to fear. However, if your company decides on its own initiative to install air brakes on its mobile structure trailers, such brakes must conform to the air brake standard if the trailer is built on or after the effective date of the standard, January 1, 1973.; Please advise us if further clarification is needed. Sincerely, Lawrence R. Schneider, Acting Chief Counsel |
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ID: aiam5144OpenMr. L. J. Sharman 314 Lakeside Drive South Surfside Beach, SC 29575; Mr. L. J. Sharman 314 Lakeside Drive South Surfside Beach SC 29575; "Dear Mr. Sharman: This responds to your letter of November 18, 1992 regarding the test procedure in Standard No. 302, Flammability of Interior Materials. Your questions and the answer to each follows. Question 1. MVSS-302, in Section S5.3(e), states that the timing for each specimen be started when the flame from the burning specimen reaches a point 1.5 inches from the open end of the specimen and, in Section S5.3(f), is stopped when the flame progresses to a point 1.5 inches from the clamped end of the specimen. Further, the Standard, in Section S5.2.2, states the specimen is oriented so that the surface closest to the occupant compartment air space faces downward on the test frame. The question that has been raised is whether the timing is started and stopped when the flame reaches the designated points on the surface of the specimen closest to the occupant compartment air space (the surface facing down during the test), or when the flame reaches the designated points on the surface of the specimen facing away from the occupant compartment air space (the surface facing up during the test). You suggest that the timing should be started and stopped when the flame reaches the designated points on the surface facing up during the test. As explained below, NHTSA disagrees. Section S4.3(a) of Standard No. 302 states: When tested in accordance with S5, material described in S4.1 and S4.2 shall not burn, nor transmit a flame front across its surface, at a rate of more than 4 inches per minute. However, the requirement concerning transmission of a flame front shall not apply to a surface created by the cutting of a test specimen for purposes of testing pursuant to S5. Any surface not created by the cutting of the test specimen, including the surface oriented downward pursuant to S5.2.2, is required to comply with the burn-rate requirement of S4.3(a). Surfaces created by the cutting of the test specimen were excluded from this requirement in a final rule published on March 31, 1975 (40 FR 14318). The reasons for the exclusion were stated in the notice as follows: (C)utting certain materials to the prescribed thickness produces a tufted surface upon which a flame front may be propagated at a faster rate than it would be upon the surface of the material before cutting, thereby creating an artificial test condition. Because of this exclusion, the surface facing upward pursuant to S5.2.2 is not required to comply with the burn-rate requirement of S4.3(a) if the surface was created by cutting the material to be tested to the prescribed thickness. In addition, I note that S5.3(b) requires the test specimen to be placed in the center of the cabinet. Therefore, it should not be any more difficult to observe the progress of the flame on the surface facing down than the surface facing up. Question 2. MVSS-302, in Section S5.3(f), states that the flame progression be measured to a point 1.5 inches from the clamped end of the specimen under test. The standard does not specify actions to be taken after timing has stopped. Some laboratories put out the flame using a small amount of water from a spray bottle. The question has been raised as to whether using a small amount of water from a spray bottle to put out the flame is an acceptable procedure. You are correct that Standard No. 302 does not specify a procedure to extinguish the flame after the test. Therefore, spraying a specimen with a small amount of water to extinguish the flame would be acceptable. However, please bear in mind that S5.1.2 states Prior to testing, each specimen is conditioned for 24 hours at a temperature of 70 F. and a relative humidity of 50 percent, and the test is conducted under those ambient conditions. After spraying a specimen in the test cabinet, it would be necessary to ensure that the ambient conditions in the cabinet conform to those specified in S5.1.2 before conducting any additional tests. I hope you find this information helpful. If you have any other questions, please contact Marvin Shaw of my staff at this address or by phone at (202) 366-2992. Sincerely, John Womack Acting Chief Counsel"; |
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ID: aiam2681OpenMr. Jerry McNeil, American Trailers, Inc., 1500 Exchange Avenue, Box 26568, Oklahoma City, OK 73126; Mr. Jerry McNeil American Trailers Inc. 1500 Exchange Avenue Box 26568 Oklahoma City OK 73126; Dear Mr. McNeil: This responds to your July 20, 1977, letter asking whether you certification labels comply with Part 567, *Certification*, and Standard No. 120, *Tire Selection and Rims for Motor Vehicles Other Than Passenger Cars*.; As stated to you in an earlier letter, the National Highway Traffi Safety Administration does not issue approvals of compliance with Federal safety standards and regulations. The agency will, however, give you an informal opinion as to whether your labels appear to comply with the requirements. The agency has determined that the two labels that you submitted do not follow the format established in the regulations and, therefore, do not comply with the requirements. If 'R' denotes radial ply and 'F' denotes load range, the tire designation should be 10.00 R 20(F).; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam3993OpenMr. Douglas I. Greenhaus, Senior Attorney/Regulatory Affairs, National Automobile Dealers Association, 8400 Westpark Drive, McLean, VA 22102; Mr. Douglas I. Greenhaus Senior Attorney/Regulatory Affairs National Automobile Dealers Association 8400 Westpark Drive McLean VA 22102; Dear Mr. Greenhaus: Thank you for your letter of July 8, 1985, to Stephen Oesch of m staff. You asked us to confirm your understanding of how our regulations would affect the alteration of a new vehicle prior to its sale.; Your question specifically relates to a situation in which a deale wants to switch, prior to sale of the vehicle, the bucket seats from one new motor vehicle to another new vehicle of the same model. You explained in a phone conversation with Mr. Oesch that changing the seats might involve some cutting and welding of the seats or their tracks. Under Part 567.7 (49 CFR Part 567.7) of our regulations, we would consider the dealer to be an 'alterer'. After completing the alteration, the dealer would be required by Part 567.7 to certify that the vehicle, as altered, complies with all applicable Federal Motor Vehicle Safety Standards. Depending on the specific design of the vehicle seat and the actual alterations performed, the replacement of a seat would be affected by Federal Motor Vehicle Safety Standard No. 207, *Seating Systems*, and could be affected by Standard No. 208, *Occupant Crash Protection*, and Standard No. 210, *Seat Belt Assembly Anchorages*.; Thank you for providing us with the information on glass tinting. hope this information on vehicle alteration is of assistance to you. If you have further questions, please let me know.; Sincerely, Jeffrey R. Miller, Chief Counsel |
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ID: aiam0716OpenMr. John B. White, Engineering Manager, Michelin Tire Corporation - Technical Division, 2500 Marcus Avenue, Lake Success, New York 11040; Mr. John B. White Engineering Manager Michelin Tire Corporation - Technical Division 2500 Marcus Avenue Lake Success New York 11040; Dear Mr. White: #In reply to your letter of May 16, 1972, you interpretation is correct that paragraph S4.3.2 of Motor Vehicle Safety Standard No. 109 requires either the manufacturer's name and his assigned code number, or the brand name and the manufacturer's assigned number to be labeled onto the tire. The code number must appear in either case. #Yours truly, Richard B. Dyson, Assistant Chief Counsel; |
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ID: aiam3839OpenMr. G. Couffinhal, Cibie/Marchal, 17, rue Henri Gautier, 93012 Bobigny Cedex, France; Mr. G. Couffinhal Cibie/Marchal 17 rue Henri Gautier 93012 Bobigny Cedex France; Dear Mr. Couffinhal: This is in reply to your letter of April 19, 1984, to Richard Va Iderstine of this agency. With respect to the standardized light source socket for replaceable bulb headlamps, you have asked whether a bulb socket design with a 'bottom view' diameter of 29.7 mm. etc. would be acceptable.; As you have noted, Dimension P of Figure 3-7 and 3-8 of Standard No 108 specifies a millimeter dimension of '(28.75 to 28.65)'. The dimension of your design exceeds this figure, and is therefore noncompliant with requirements intended to insure proper function with standardized replaceable light sources. It is not permitted by Standard No. 108.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam1804OpenMr. Charles J. Calvin, President, Truck Trailer Manufacturers Association, 2430 Pennsylvania Avenue, N.W., Washington, DC 20037; Mr. Charles J. Calvin President Truck Trailer Manufacturers Association 2430 Pennsylvania Avenue N.W. Washington DC 20037; Dear Mr. Calvin: It has come to the attention of the National Highway Traffic Safet Administration that a 'Recommended Practice' issued by the Truck Trailer Manufacturers Association, titled 'Method for Determining GAWR and GVWR for Truck Trailer Certification' may be misleading some trailer manufacturers in their responsibilities to certify their products to Standard No. 121, *Air Brake systems*. The recommended practice was reviewed by the NHTSA in draft form to determine its consistency with Parts 567, *Certification*, and 568, *Multi-stage vehicle manufacture*, of Title 49 of the Code of Federal Regulations.; The NHTSA in a March 30, 1972, letter to Mr. Vincent Grey found th draft consistent with Parts 567 and 568. The draft discusses, among other things, the method for determining the gross axle weight rating (GAWR) of an axle at a speed lower than full highway speed. It appears, however, that some manufacturers have understood the draft's discussion to set out the entirety of their responsibilities under the safety standards, and in particular, Standard No. 121. Although the March 30, 1972, review of the TTMA procedures did approve the use of speed qualifications in establishing GAWR and GVWR on Certification labels, our review only recognized the possibility that in some cases GAWR and GVWR might be properly established on the basis of a speed limitation. (An example of such a possibility would be for a vehicle which was physically incapable of reaching highway speeds.); We do not consider it reasonable to extend that interpretation t permit a manufacturer to establish a reduced- speed rating to avoid a safety standard such as Standard No. 121. A vehicle capable of highway speeds and reasonably expected to be operated at such speeds is subject to Standard No. 121 at weight ratings specified for highway speeds.; In view of the misunderstanding that has arisen, we believe i necessary to clarify our approval letter of March 30, 1972, insofar as it relates to the establishment of GAWR and GVWR. These values, to meet the requirements of SS 567.4(g)(3) and (4), must henceforth be unqualified ratings, and may not be based on reduced speeds. If reduced-speed ratings are to be established, they must be *in addition to* the unqualified ratings, and must appear at the end of the certification label, or on a separate label, and in either case be accompanied by an adequate explanation as to the scope of their use.; We realize that this clarification may force revision of the practice of some of your members. Manufacturers who have utilized this practice should be advised immediately that it is inappropriate under the requirements.; Yours truly, James C. Schultz, Chief Counsel |
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ID: aiam5514OpenThe Honorable Tillie K. Fowler Member, U.S. House of Representatives 4452 Hendricks Avenue Jacksonville, FL 32207; The Honorable Tillie K. Fowler Member U.S. House of Representatives 4452 Hendricks Avenue Jacksonville FL 32207; "Your Reference: 95-0167-J Dear Congresswoman Fowler: Thank you fo your letter on behalf of your constituent, Mr. Dail Taylor of St. Augustine, Florida. Mr. Taylor requested assistance, stating that his company would have to stop manufacturing passenger motor vehicles if the vehicles must meet the Federal Motor Vehicle Safety Standards (FMVSSs). I appreciate the concerns of Mr. Taylor as a small businessman and offer the following information. In order to protect motorists and their passengers, a Federal statute requires the National Highway Traffic Safety Administration to issue FMVSSs regulating motor vehicles and motor vehicle equipment. Mr. Taylor's company, Goodlife Motor Company, wrote to NHTSA asking whether their 'super golf cars' were motor vehicles and therefore subject to the FMVSSs. NHTSA's Chief Counsel responded by letter that the answer was 'yes'. We were informed that the 'super golf cars' are intended for use on public roads. NHTSA has two criteria for determining whether a vehicle that regularly uses the public roads is considered to be a 'motor vehicle.' A vehicle is not a motor vehicle if it meets both of the following criteria: the vehicle has an abnormal configuration distinguishing it from other vehicles, and the vehicle cannot attain speeds over 20 miles per hour (mph). The 'super golf cars' do not meet either criterion. We have determined that because the vehicles resemble passenger cars, they do not have an abnormal configuration. As to speed, we note that the top speed of the vehicles, 29 mph, is approximately the speed at which NHTSA conducts crash tests to see whether vehicles meet certain safety standards. It is also a speed at which vehicle occupants can readily suffer serious or even fatal injuries in a crash. We note further that older adults are more susceptible than younger adults to injury in motor vehicle crashes. This is particularly important since we understand that one of the primary expected uses of the 'super golf car' is in retirement communities. As motor vehicles, the 'super golf cars' must meet the FMVSS. As the president of a small business, Mr. Taylor has a number of compliance options. First, he can comply with the current safety standards. I appreciate that the costs of compliance would be significant. Second, Mr. Taylor may petition NHTSA to initiate rulemaking to amend the current safety standards to accommodate any special compliance problems that a small car might experience. NHTSA has authority to establish different levels of requirements for vehicles of different sizes. However, it lacks the authority to vary the stringency of requirements based on the size of a vehicle manufacturer. Third, NHTSA has authority to grant temporary exemptions to small manufacturers. Mr. Taylor may petition for a temporary exemption from one or more of the safety standards. However, as we explained to Mr. Taylor, temporary exemptions are primarily granted as an interim measure to give small manufacturers a chance to come into compliance. Further, the exemptions are typically given for only a select number of the standards applicable to an exempted vehicle. Across-the-board exemptions from all standards have not been granted. Mr. Taylor may himself prepare and submit any petition. We have enclosed copies of our regulations regarding petitions for rulemaking and petitions for exemption. If Mr. Taylor has any questions or needs further information on how to proceed under any of the three options discussed above, we will gladly provide assistance. Please ask him to contact Taylor Vinson at (202)366-2992. Sincerely, Carol Stroebel, Director Intergovernmental Affairs Enclosures"; |
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ID: aiam1557OpenMr. P.K. Kamath, Senior Safety Engineer, Oshkosh Truck Corporation, P.O. Box 2566, Oshkosh, WI 54901; Mr. P.K. Kamath Senior Safety Engineer Oshkosh Truck Corporation P.O. Box 2566 Oshkosh WI 54901; Dear Mr. Kamath:#This is in reply to your letter of July 9, 1974 asking whether Standard No. 101 requires identification and illumination of an emergency engine stop control, in addition to the engine stop control intended for normal use.#The 'engine stop' control referred to in Standard No. 101 means any control used to stop the engine, and would include the emergency control. If it is important for the normal control to be identified and illuminated, it is all the more important that a control intended for emergency use meet the requirements of the standard. Identification such as 'emergency engine stop' would be acceptable under Standard No. 101. Illumination, of course, must meet the requirements of the standard, but since you have not described the emergency system or its location we cannot offer a more precise comment.#Yours truly, Richard B. Dyson, Acting Chief Counsel; |
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ID: aiam3090OpenMr. Karl-Heinz Ziwica, Safety & Emission Control Engineering, BMW of North America, Inc., Montvale, New Jersey 07645; Mr. Karl-Heinz Ziwica Safety & Emission Control Engineering BMW of North America Inc. Montvale New Jersey 07645; Dear Mr. Ziwica: This is in reply to your letter of May 16, 1979, to Mr. Schwartz of m office, and in confirmation of your subsequent telephone conversation with him.; You wish to know whether Federal Motor Vehicle Safety Standard No. 115 *Vehicle identification number*, permits BMW to use all the permissible numerical digits in the 11th position of the vehicle identification number (VIN) for each of its two plants, as long as each VIN in its entirety assigned to each individual vehicle uniquely identifies its plant of manufacture. A system such as you suggest was proposed in the notice of proposed rulemaking for this standard issued on January 16, 1978 (Docket No. 1-22, Notice 4, 43 FR 2189). The response to this particular proposal was negative, and the rule issued on August 17, 1978, withdrew it. Consequently, the 11th character of the VIN must in and of itself be decipherable into the plant of manufacture (S4.5.3.2).; This is not to say, however, that BMW does not have considerabl flexibility in its utilization of the 11th position. A pointed out in Notice 8 (44 FR 17489, March 22, 1979), BMW can submit more than one character to represent a single plant. While this restriction unfortunately may result in some change to the system which BMW is currently employing, the agency believes that a sophisticated allotment of sequential blocks will alleviate at least some of the problems which you foresee.; 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.