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: aiam0653OpenMr. Heinz W. Gerth, Assistant Vice President, Mercedes-Benz of North America, Inc., 158 Linwood Plaza, Fort Lee, NJ 07028; Mr. Heinz W. Gerth Assistant Vice President Mercedes-Benz of North America Inc. 158 Linwood Plaza Fort Lee NJ 07028; Dear Mr. Gerth:#On November 9, 1971, you wrote concerning th requirement in Standard No. 101 that a control be provided to adjust the intensity of control illumination, continuously variable from an 'off' position to a position providing illumination sufficient for the vehicle operator to readily identify controls under conditions of reduced visibility. You asked an interpretation that 'the term 'off' means a control position which provides minimal control illumination which is not distracting to the driver who has adapted to dark ambient roadway conditions.'#In our opinion, the word 'off' means a control position providing no illumination, and we therefore do not concur in your interpretation. You have asked, however, as an alternative, that your letter be considered as a petition for rulemaking to amend Standard No. 101 to provide an option permitting the type of control already incorporated in Mercedes-Benz vehicles.' We have tentatively determined that your petition has merit, and that quantitative levels for control illumination intensity should be established in Standard No. 101. We shall therefore initiate appropriate rulemaking with a proposed effective date of September 1, 1973.#Sincerely, Douglas W. Toms, Administrator; |
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ID: aiam1941OpenMr. Donald W. Taylor, Manager, Product Safety & Quality, Volvo of America Corporation, Rockleigh, NJ 07647; Mr. Donald W. Taylor Manager Product Safety & Quality Volvo of America Corporation Rockleigh NJ 07647; Dear Mr. Taylor: This responds to Volvo of America Corporation's May 9, 1975, reques for reconsideration of the NHTSA's March 31, 1975, determination that a Volvo brake system that employs air pressure modulated by the vehicle operator to provide the energy used to actuate the brakes is an air brake system subject to Standard No. 121, *Air brake systems*.; Having reviewed all of the data submitted with your letter, it i concluded that the Volvo system is an air brake system subject to Standard No. 121. In the development of separate air brake and hydraulic brake system standards, the NHTSA had to make a determination of the status of brake systems which employ both air and hydraulic fluid as a means of transmitting force to the vehicle brakes. The agency decided that use of air as a means of power and transmission of the brake force would qualify the system as an air brake system. This decision permits manufacturers to determine with certainty whether a standard applies to their products.; Since the withdrawal of applicability to trucks of Standard No. 105-75 *Hydraulic brake systems*, our decision has had the beneficial effect of ensuring that 'air over hydraulic' systems are subject to a braking standard. If you are aware of any adverse safety consequences of our decision, I would appreciate hearing from you.; Sincerely, Robert L. Carter, Associate Administrator, Motor Vehicl Programs; |
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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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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.