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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| search results table | |
ID: aiam5434OpenMs. Sally O'Cordan Ashley, Hannula, & Halom 515 Belknap Street Superior, WI 54880; Ms. Sally O'Cordan Ashley Hannula & Halom 515 Belknap Street Superior WI 54880; "Dear Ms. O'Cordan: This responds to your question about whether an Federal motor vehicle safety standard (FMVSS) applies to glass used in a travel trailer. You stated that your law office was investigating an accident in which an individual was injured by glass of such a vehicle. Please be aware that no FMVSS applies to the glazing (the term the agency uses for glass) in trailers. The agency has issued one standard, FMVSS No. 205, Glazing Materials, (49 CFR 571.205), which applies to glazing in some motor vehicles. However, this standard does not apply to glazing in trailers, which our regulations define as 'a motor vehicle with or without motive power, designed for carrying persons or property and for being drawn by another motor vehicle' (49 CFR 571.3). You may wish to contact the State of Wisconsin about the regulation of glass in trailers. The State has the authority to regulate the operation and modification of vehicles by their owners. Wisconsin may have used this authority to issue regulations about glazing in travel trailers. I hope this information is helpful. Please feel free to contact Marvin Shaw of my staff at this address or by telephone at (202) 366-2992 if you have any further questions or need additional information. Sincerely, John Womack Acting Chief Counsel"; |
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ID: aiam5121OpenMr. Donald Ray McCray 620694, Darrington Unit Rt. 3 P.O. Box 59 Rosharon, TX 77583; Mr. Donald Ray McCray 620694 Darrington Unit Rt. 3 P.O. Box 59 Rosharon TX 77583; "Dear Mr. McCray: This responds to your letter of November 16, 1992 t former Secretary Card. Your letter has been referred to my office for reply, because the National Highway Traffic Safety Administration (NHTSA) administers Federal regulations for motor vehicle safety. Your letter expresses concern about the buses that the Texas Department of Criminal Justice (DCJ) uses to transport inmates. You believe the buses are unsafe and operated in violation of Federal law. As explained below, it appears the DCJ did not violate any NHTSA regulation. The National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1381 et seq., the Safety Act) authorizes this agency to issue Federal motor vehicle safety standards (FMVSS's) that apply to the manufacture and sale of new motor vehicles and new items of motor vehicle equipment. Under the Safety Act, each person selling a new bus must ensure that the bus complies with the FMVSS's for buses. NHTSA's requirements for vehicle seats are set forth in FMVSS No. 207, Seating Systems. However, that standard does not require seat covers or pads for any bus seat. Also, there is no FMVSS that requires buses to be heated. NHTSA does not regulate the use of motor vehicles, such as the speed at which the DCJ must operate the bus. Individual states, not the Federal government, have authority over the use of vehicles. Texas state officials would be best able to answer your concerns about the manner in which you were transported. I hope you find this information helpful. If you have any other questions, please contact us. Sincerely, John Womack Acting Chief Counsel"; |
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ID: aiam0323OpenMr. Phillip N. Shrake, Standards Director, Recreational Vehicle Institute, 2720 Des Plaines Avenue, Des Plaines, IL 60018; Mr. Phillip N. Shrake Standards Director Recreational Vehicle Institute 2720 Des Plaines Avenue Des Plaines IL 60018; Dear Mr. Shrake: This is in reply to your letter of April 8, 1971, requesting confirmation of your understanding as to two sections of Standard No. 208, Occupant Crash Protection.; You are correct in reading section S4.3 to provide options for truck and multipurpose passenger vehicles with a GVWR of 10,000 pounds or less.; You are also correct in reading S4.2.2 and S4.2.3 to mea 'chassis-mount camper' when the term 'vehicles carrying chassis- mount campers' is used.; The petitions filed by RVI requesting amendments to Standards No. 20 and 210 are under active consideration and you should expect to receive an answer in the very near future.; Sincerely, Lawrence R. Schneider, Acting Chief Counsel |
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ID: aiam0289OpenMr. W.D. Nonnamaker, Director-Tire Engineering and Development, Seiberling Tire & Rubber Company, Akron, OH 44309; Mr. W.D. Nonnamaker Director-Tire Engineering and Development Seiberling Tire & Rubber Company Akron OH 44309; Dear Mr. Nonnamaker: This is in reply to your letter of January 28, 1971, to Mr. Dia concerning Part 574 - Tire Identification and Record Keeping regulations and to confirm that the fourth grouping, date code, may be placed at the end of the tire identification number by means of a separate serial tin and be separated from the third grouping by a space which will not exceed 3/4 of an inch.; Sincerely, Lawrence R. Schneider, Acting Chief Counsel |
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ID: aiam5571OpenK. Howard Sharpe, Esq. Aranson Law Office P.O. Box 5296 Grand Forks, ND 52806-5296; K. Howard Sharpe Esq. Aranson Law Office P.O. Box 5296 Grand Forks ND 52806-5296; Dear Mr. Sharpe: This responds to your further letter of June 13, 1995 with reference to your client, NYTAF Industries, Inc. You have informed us that NYTAF will sell in the aftermarket its rear lighting system that displays verbal messages. You ask whether NYTAF must certify compliance with the Federal motor vehicle safety standards as 'it is simply a manufacturer of an accessory.' The answer is no. The only aftermarket lighting equipment for which certification of compliance is required is equipment that is manufactured to replace any item of required original lighting equipment on a vehicle. The NYTAF system is not intended to replace any item of original equipment, and no certification is required. However, because the NYTAF system is 'manufactured or sold . . . as an accessory or addition to a motor vehicle', it is 'motor vehicle equipment' as defined by 49 U.S.C. 30102(a)(7)(B). This means that if either NYTAF or NHTSA determines that there is a safety related defect in the system, NYTAF will be required to notify and remedy according to statutory provisions. If you have any further questions you may refer them to Taylor Vinson of this Office (202-366-5263). Sincerely, John Womack Acting Chief Counsel Enclosure; |
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ID: aiam0773OpenMr. W. Dershko, Engineering Manager, Motor Coach Industries, Inc., Pembina, ND 58271; Mr. W. Dershko Engineering Manager Motor Coach Industries Inc. Pembina ND 58271; Dear Mr. Dershko: This is in reply to your letter of April 17, 1972, in which yo requested our interpretation of several sections of Standard 121. I apologize for our delay in replying.; Your first question concerns the air reservoirs which are considered t be included in the service reservoir system. As shown in your diagram, three tanks are capable of providing air to the service brake chambers: the wet air tank, the dry air tank, and the accessory tank. The first two tanks are clearly part of the service reservoir system. The accessory tank, however, has not been generally considered as part of the service brake system, and it is our opinion that it should not be included in computing the reservoir system capacity.; Although the exclusion of the accessory tank from the service reservoi system would seem to weigh against the present location of your pressure gauge in the accessory system circuit, there is another feature of its operation in its present location which leads us to conclude that it would not be acceptable under the present wording of S5.1.4. In the event of a pressure loss in the accessory system (your Condition No. 1), the gauge would accurately indicate the pressure in the dry tank until the pressure falls to 65 p.s.i., at which point the gauge would cease to indicate the dry tank pressure and would be only an accessory tank gauge. Thus, if the check valve functions properly, the dry tank would be at 65 p.s.i. even though the gauge may read 0 p.s.i. Because the pressure deliverable to the brake from the service reservoir system would be the 65 p.s.i. of the dry tank, the gauge would not be indicating the service reservoir system air pressure as required by S5.1.4.; Your third question is whether the vehicle must be stationar throughout the static retardation force test of S5.6.1. Our reply is that the vehicle need not remain stationary. Its friction may be overcome by the test pull, although it must exert a force of the magnitude specified in the section.; Your last question relates to the treatment of trailing axles under th requirements of S5.7.1. You indicate that you presently offer an automatic emergency system as an option and that it appears inconsistent to require parking brakes on each axle under the automatic application option when they are not required on each axle under the other option. We are continuing our evaluation of the parking brake requirements, including the axle-by-axle braking required by S5.7.1. At this time it has not been decided whether to formally institute rulemaking to adjust the requirements. We will advise you if such rulemaking will be forthcoming.; Sincerely, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam1861OpenMr. Danny Lanzdorf, Supervising Engineer, Oshkosh Truck Corporation, P.O. Box 2566, Oshkosh, WI 54901; Mr. Danny Lanzdorf Supervising Engineer Oshkosh Truck Corporation P.O. Box 2566 Oshkosh WI 54901; Dear Mr. Lanzdorf: This responds to your March 11, 1975, request for confirmation tha four Oshkosh snowplows qualify for exclusion from Standard No. 121, *Air brake systems*, under criteria set out in S3. You enclose photographs of the vehicles and state that they have all-wheel drive, a maximum attainable speed of 45 mph, and that three of the vehicles have no cargo- carrying capacity. The fourth vehicle has a dump body used for maintenance and construction purposes.; As you describe the vehicles, the first three meet the criteria an would be excluded from the standard. The fourth vehicle has a dump body which qualifies as 'cargo-carrying' and therefore the vehicle does not meet the criteria for exclusion.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam4730OpenMr. Earl W. Dahl Vice President The Goodyear Tire & Rubber Company Akron, Ohio 44316-0001; Mr. Earl W. Dahl Vice President The Goodyear Tire & Rubber Company Akron Ohio 44316-0001; "Dear Mr. Dahl: This responds to your letter seeking an interpretatio of 49 CFR 574, Tire Identification and Recordkeeping. Specifically, you asked whether an additional symbol, which is intended to identify more precisely the year of manufacturer, is permitted to be included in the tire identification number. As explained below, the answer is yes. The purpose of the tire identification requirements is to facilitate the effective recall of tires from the public if the tires are found not to comply with the applicable safety standards or if the tires contain a safety related defect. Section 574.5 requires that each tire be marked with the tire identification number. In particular, it requires that the fourth grouping contain three numerals of which the first two identify the week of the year and the third numeral identifies the year of manufacture. You believe that this requirement may lead to confusion because the third numeral, e.g. '9', could refer to more than one year, e.g., 1979 or 1989. Accordingly, you state that your company would like to be able to distinguish the year of manufacture in an interval longer than one decade. To do this, you would like to add a symbol immediately following the fourth grouping of the tire identification number to identify that this tire was produced in the decade 1990 through 1999. Standard No. 109, New pneumatic tires (49 CFR 571.109) and Standard No. 119, New pneumatic tires for vehicles other than passenger cars (49 CFR 571.119) together with Part 574 require that certain information be labeled on the sidewalls of each tire subject to the standards. In a May 31, 1988 letter to Mr. Garry Gallagher of Metzeler Motorcycle Tire (copy attached), the agency explained that The agency has frequently stated in past interpretations that the purpose of these labeling requirements is to provide the consumer, in a clear and straightforward manner, with technical information necessary for the safe use of the tires. These standards permit tire manufacturers to label additional information on the sidewall on the tires, provided that the additional information does not obscure or confuse the meaning of the required information, or otherwise defeat its purpose. Applying this standard to the question you have asked, we believe that the additional symbol, an isosceles right triangle, is not prohibited from appearing on the sidewall of your company's tires. As explained above, the labeling requirements are intended to provide information about the tire, including the year of manufacture, in a clear and straightforward manner. Because the suggested symbol does not appear to introduce additional information that might obscure or confuse the meaning of the required information or otherwise defeat its purpose, the agency has determined that marking a tire with an isosceles right triangle after the tire identification code is not prohibited. Sincerely, Stephen P. Wood Acting Chief Counsel"; |
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ID: aiam1532OpenMr. James W. Long,Continental Hydraulic Hose Corp.,P.O. Box 104,Upper Sandusky, Ohio 43351; Mr. James W. Long Continental Hydraulic Hose Corp. P.O. Box 104 Upper Sandusky Ohio 43351; Dear Mr. Long:#This responds to your May 16, 1974, request for approva of Continental's banding technique to meet the requirements of Standard No. 106,*Brake hoses*, for labeling brake hose assemblies, and for use of the letter 'C' to identify Continental as an assembly manufacturer.#The NHTSA interprets a band as a label which encircles the hose completely and attaches to itself. To constitute labeling at all, of course, the band must be affixed to the hose in such a manner that it cannot be easily be removed. From this discussion, you should be able to determine the compliance of your labeling method with the standard. the NHTSA does not approve specific designs in advance because the material, installation method, and underlying material can significantly affect the quality of specific design. #The letter 'C' has already been recorded with the Office of Standards Enforcement as the manufacturer designation for Continental Gummi-Werke A.G. of Germany. Please submit another choice to: Office of Standards Enforcement, 'Brake Hose Identification', National Highway Traffic Safety Administration, 400 Seventh St. S.W., Washington D.C. 20590.#Yours truly,Richard B. Dyson,Assistant Chief Counsel; |
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ID: aiam1498OpenMr. Kenji Shimizu, Mitsubishi Motors Corporation, 24300 Southfield Road, Southfield, MI 48075; Mr. Kenji Shimizu Mitsubishi Motors Corporation 24300 Southfield Road Southfield MI 48075; Dear Mr. Shimizu: This responds to your verbal request to Mr. Herlihy of this office fo a determination that a 3-point, continuous loop, Type II seat belt assembly would meet the requirements of S4.1.2.3.1(a) of Standard No. 208 if its emergency-locking retractor were mounted at the outboard floor anchorage instead of at the roof rail. The belt is routed from the fixed upper torso end, through a slip-fitting latch and pelvic section, to the retractor.; Assuming the belt assembly meets any other adjustment requirement o S4.1.2.3.1, it would conform to S7.1 of Standard No. 208 and S4.1(g) of Standard No. 209 with the emergency -locking retractor mounted at the outboard floor anchorage. The upper torso restraint would 'adjust by means of an emergency-locking retractor' within the meaning of S7.1 as long as the continuous loop permitted slack from the floor-mounted emergency-locking retractor to reach the upper torso portion of the assembly.; Yours truly, Richard B. Dyson, Assistant 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.