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: aiam1823OpenMr. Al Zajic, American Trailers, Inc., 1500 Exchange Avenue, Box 26568, Oklahoma City, OK 73126; Mr. Al Zajic American Trailers Inc. 1500 Exchange Avenue Box 26568 Oklahoma City OK 73126; Dear Mr. Zajic: This responds to your February 19, 1975, request for confirmation tha the building of a trailer with some used components constitutes the manufacture of a new vehicle for purposes of meeting all applicable safety standards, unless the running gear and bottom rails, at a minimum, are from an existing trailer. You also ask for confirmation that parking brakes are not required on a steerable front axle of a full trailer.; The answer to both of your questions is yes. I enclose a copy of letter interpretation which sets out our position on the extent to which a vehicle can be 'repaired' before it becomes the manufacture of a new vehicle.; In answer to your second question, a full trailer, like all othe air-braked trailers, must meet the requirements of S5.6 *Parking brake system*. Section S5.6 permits the manufacturer the option of meeting the requirements of S5.6.1, *Static retardation force*, or S5.6.2, *Grade holding*.; If you choose to meet S5.6.1, you are not required to equip the fron steerable axle with a parking brake system. If you choose to meet S5.6.2, you may use whatever combination of parking brake systems will meet the grade-holding requirement, and such a combination may or may not include a parking brake system on the front steerable axle.; Because Standard No. 121 does not specify a secondary means of brakin on the steerable axle, the Bureau of Motor Carrier Safety requirement for automatic application of the brakes upon breakaway remains applicable to the axle (49 CFR S 393.42(d)).; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam2219OpenMr. Edward A. Green, President Henke Manufacturing Corp., Box 188, 525 Main, Janesville, IA 50647; Mr. Edward A. Green President Henke Manufacturing Corp. Box 188 525 Main Janesville IA 50647; Dear Mr. Green: This is in response to your January 26, 1976, letter concerning th relationship between snow plows that you manufacture and the front-axle GAWR's of the vehicles on which they are mounted. Your questions and our answers are as follows:; *Question 1*. 'Somewhere I read where fire trucks are not governed b FMVSS121 or axle weight restrictions as an emergency vehicle. Is this true?'; Standard No. 121 does not apply to fire fighting vehicles manufacture before June 1, 1976. In addition, it does not apply to such a vehicle manufactured from June 1, 1976, to August 31, 1977, that either has a GAWR for any axle of 24,000 pounds or more, or has two or more front, steerable axles with a GAWR of 16,000 pounds or more for each axle. Further, the standard does not apply to any vehicle meeting any one of criteria (a) through (d), as follows:; >>>(a) An overall vehicle width of 108 inches or more, (b) An axle that has a GAWR of 29,000 pounds or more, (c) A speed attainable in two miles of not more than 33 mph, or (d) (1 A speed attainable in two miles of not more than 45 mph, and (2) An unloaded vehicle weight that is not less than 95 percent of the vehicle GVWR, and (3) No passenger-carrying capacity.; *Question 2*. 'Do you consider a snow plow an emergency piece o equipment?'; There are no exemptions in the Federal motor vehicle safety standard or regulations for 'emergency vehicles' or 'emergency equipment'.; *Question 3*. 'Would a D.O.T. compliance officer require a plow to b raised for weighing to check the GAWR?'; In determining whether a vehicle equipped with a snow plow has bee assigned an improper GAWR, the NHTSA will consider the load imposed on the axle system when the plow is in the raised position.; *Question 4*. 'The box or fold down flap I mention in letter - woul this be considered a legal method of meeting GAWR, assuming it was part of a snow plow procedure program?'; Our letter of May 9, 1974, explained that proper weight ratings depen on what you, as a vehicle alterer, know, or can reasonably be expected to know, about how the plow-equipped trucks are likely to be loaded. It stated further:; >>>A warning to the buyer not to exceed the rated cargo load or th weight ratings. . .would not be sufficient if it were reasonable to expect that the vehicles would, in practice, exceed these ratings at normal full load despite the warning.<<<; Similarly, if the volume-reducing purpose of the box or fold down fla described in your letter to county engineers is likely to be defeated (whether intentionally of (sic) accidentally), then neither would be sufficient to validate a GAWR that would otherwise be exceeded by a fully loaded axle. If, on the other hand, it is reasonable to expect that your recommended loading procedure will be followed, then it is permissible to base the GAWR on the correspondingly reduced 'full' load.; *Question 5*. 'When weighing a truck for compliance would a full loa of ballast be required even though the snow plowing procedure of governmental bodies call out a less than full load of ballast?'; The considerations discussed in no. 4 above apply here as well. *Question 6*. 'When we bid to a State where drawings and or detaile specifications of snow removal equipment are called out and no axle sizes or dump box sizes are called out are we responsible for this plow overweighing a front axle? We do not mount any equipment, we furnish equipment as specified.'; The primary responsibility for weight ratings is with the party who, b mounting the snow plow, is the vehicle alterer. If, however, your advertising or bids promote the use of the snow plow in situations where front axles are likely to be overloaded, then the plow may be considered to contain a defect relating to motor vehicle safety, which would be subject to the notification and remedy provisions of the National Traffic and Motor Vehicle Safety Act of 1966, as amended.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam0224OpenMr. Folke Kohler, Scandex Sakerhetsglas Akteibolag, Box 218, S-261 22 Londskrona 1, Sweden; Mr. Folke Kohler Scandex Sakerhetsglas Akteibolag Box 218 S-261 22 Londskrona 1 Sweden; Dear Mr. Kohler: This is in reply to your letter of March 3, 1970 in which you applie to the National Highway Safety Bureau for registration of glazing materials your company intends exporting to the United States for use in motor vehicles.; It is important that you understand that the National Highway Safet Bureau does not approve or certify that glazing materials meet the requirements of the Federal Motor Vehicle safety Standard applicable thereto (No. 205, copy enclosed). Section 114 of the National Traffic and Motor Vehicle Safety Act of 1966, 15 U.S.C. 1403 (a copy of the Act is also enclosed) requires the manufacturer to certify that his product complies with all applicable U.S. standards. You may certify that your company's glazing materials meet the standard by following the requirements of Section 114 of the Act or by following the certification alternative provided for in S3.4 of Standard No. 205. If you choose to use the alternative method provided for in the Standard you must apply for an approved manufacturer's code mark.; Although the Bureau does not certify glazing material as complying, i does conduct a compliance program to determine if the manufacturer's product does, in fact, comply with the applicable standards. Persons selling non-complying items of motor vehicle equipment are subject to a civil penalty of up to $1,000 per violation (see Sections 108 and 109 of the Act).; In addition, your attention is directed to Section 110(e) of the Ac which requires persons exporting motor vehicles and motor vehicle equipment into the United States to designate an agent for service of process. See Subpart D-Service of Process: Agents, of the General Procedural Rules (copy enclosed).; Sincerely, Lawrence R. Schneider, Chief, Regulations Division |
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ID: aiam5026OpenMr. Thomas Turner Manager, Engineering Services Blue Bird Body Company P.O. Box 937 Fort Valley, GA 31030; Mr. Thomas Turner Manager Engineering Services Blue Bird Body Company P.O. Box 937 Fort Valley GA 31030; "Dear Mr. Turner: This responds to your letter asking about Federa Motor Vehicle Safety Standard No. 131, School Bus Pedestrian Safety Devices, with respect to the automatic extension of a stop signal arm. You were especially concerned with the interaction between a provision in Wisconsin's Administrative Code requiring activation of the stop signal arm under specified conditions and the stop signal arm activation requirements set forth in Standard No. 131. I have responded in detail to your questions below. Before I answer your question about your company's design for complying with both the Wisconsin Code and Standard No. 131, I would like to note that it does not appear that the Wisconsin regulation is inconsistent with Standard No. 131 with respect to the stop signal arm activation requirements. The Wisconsin Administrative Code states that: 'Any bus manufactured after January 1, 1978, shall have the stop signal arm controlled by the service door. The stop signal arm shall not become operational until the service door opens. The stop signal arm shall be installed in such a manner that it cannot be activated unless the alternating red lamps are in operation.' S5.5 of Standard No. 131 states that 'The stop signal arm shall be automatically extended in such a manner that it complies with S5.4.1, at a minimum whenever the red signal lamps required by S5.1.4 of Standard No. 108 are activated...' (emphasis added) Both the Wisconsin requirement and the requirement in Standard No. 131 tie the activation of the stop signal arm to the operation of the red signal lamps. In addition, the Wisconsin regulation also ties the activation of the stop signal arm to the opening of the service door. Based on this information, it appears that a manufacturer could comply with both Standard No. 131 and the Wisconsin regulation by designing its school buses so that opening the service door automatically activates both the stop signal arm and the red flashing lamps. If the Wisconsin regulation were interpreted in a way that does not tie the automatic extension of the stop signal arm to opening the service door, then there could be an inconsistency with Standard No. 131. You asked whether Blue Bird's system for activating the stop signal arm in accordance with Wisconsin's requirement complies with the requirements of Standard No. 131. You explained that, on its school buses sold in Wisconsin, Blue Bird provides a system by which the alternating red flashing lamps are activated by a driver controlled manual switch and the stop signal arm is activated by opening the service door. Under this system, the red flashing lamps are activated before the service door has been opened and before the stop signal arm has been extended. Based on the information provided in your letter, we conclude that Blue Bird's system would not comply with the requirements of Standard No. 131. Standard No. 131 explicitly requires the stop signal arm to be automatically deployed whenever the red signal lamps required by Standard No. 108 are activated. As explained in the final rule adopting Standard No. 131, 'any system of activation is permissible provided the stop signal arm is extended during, at least, the entire time that the red warning lamps are activated.' (56 FR 20363, 20368, May 3, 1991). As described in your letter, the system your company has developed for its Wisconsin school buses has the red warning lamps activated by a manual switch and the activation of those lamps does not activate the stop signal arm. Hence, that system does not comply with the explicit requirement of Standard No. 131 that the stop signal arm be automatically extended whenever the red warning lamps are activated. I hope this information is helpful. If you have any further questions about NHTSA's safety standards, please feel free to contact Marvin Shaw of my staff at this address or by telephone at (202) 366-2992. Sincerely, Paul Jackson Rice Chief Counsel"; |
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ID: aiam2649OpenMr. Jac H. Karlan, 37-A Haddon Road, Cranbury, NJ 08512; Mr. Jac H. Karlan 37-A Haddon Road Cranbury NJ 08512; Dear Mr. Karlan: This is in response to your letter of June 10, 1977, requesting advic as to how your bumper-attachable energy absorber can be tested in order to establish its efficacy.; As you probably know, the National Highway Traffic Safet Administration (NHTSA) has promulgated a bumper standard (49 CFR Part 581, *Bumper Standard*) that will, beginning September 1, 1978, prohibit damage to vehicle surfaces, other than the bumper, during 5 mph test impacts. Phase II of the standard, which goes into effect September 1, 1979, will prohibit any damage to the bumper that exceeds 3/8 inch dent and 3/4 inch set. Since manufacturers will be required to meet these levels of bumper performance, shock absorbers such as yours may be greatly needed.; The NHTSA does not specify any design characteristics in its standards Thus, manufacturers are permitted to choose whatever design they wish, as long as their vehicles are capable of meeting the performance criteria provided in the standard. Thus, I suggest that you communicate with the automobile manufacturers regarding use of your shock absorber.; The contracts to which you refer in your letter were for th development of total vehicles. I suggest you contact an independent laboratory for testing your energy absorber.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam0674OpenMr. Thomas S. Pieratt, Jr., Executive Secretary, Truck Equipment & Body Distributors Association, 602 Main Street, Cincinnati, OH 45202; Mr. Thomas S. Pieratt Jr. Executive Secretary Truck Equipment & Body Distributors Association 602 Main Street Cincinnati OH 45202; Dear Mr. Pieratt: This is in reply to your letter of March 28, 1972, inquiring whether State or its political subdivisions (in your particular case it is a county) may elect not to conform to any of the motor vehicle safety standards and the Certification regulations. You state that in the particular case in question the county orders new incomplete vehicles, and then transfers an old body onto the new chassis, creating a completed vehicle.; Under the existing regulations, one who transfers a used body onto new chassis is, as you have apparently assumed, a final-stage manufacturer, and is responsible for compliance with applicable standards, and the Certification regulations. There is no exemption in the National Traffic and Motor Vehicle Safety Act, or the standards or certification requirements, for counties or other State governmental units that manufacture completed vehicles. Consequently, the county is responsible in the situation you describe for completing the vehicles in question in such a manner that they conform to all applicable motor vehicle safety standards, and for certifying conformity with the standards in accordance with the certification requirements.; We are pleased to be of assistance. Sincerely, Lawrence R. Schneider, Chief Counsel |
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ID: aiam1966OpenMs. Michelle Bolton, Cedar Park Plaza, P.O. Box 767, Cedar Park, TX 78613; Ms. Michelle Bolton Cedar Park Plaza P.O. Box 767 Cedar Park TX 78613; Dear Ms. Bolton: This is in response to your letter of June 12, 1975, concernin requirements for automobile air conditioning units, which was forwarded to this office by the Environmental Protection Agency.; We have established no requirements, general or specific, fo automobile air conditioning units. As a result, we have no material to provide you.; If you have further questions, feel free to write again. Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam5476OpenMr. Kenneth Sghia-Hughes Research Engineer Solectria Corporation 68 Industrial Way Wilmington, MA 01887; Mr. Kenneth Sghia-Hughes Research Engineer Solectria Corporation 68 Industrial Way Wilmington MA 01887; "Dear Sir: We have received your letter of December 8, 1994, wit respect to the applicability of two Federal motor vehicle safety standards to electric vehicles. With respect to Standard No. 301 Fuel System Integrity, you believe that the language of S3 implies that 'it applies to all passenger vehicles, but to only those trucks with GVWR of 10,000 pounds or less and that use fuel with a boiling point above 32 degrees F.' You conclude, however, that 'this standard appears not to apply to electric vehicles with no liquid fuel.' Under S3 of Standard No. 301, the standard applies to certain specified vehicles that 'use fuel with a boiling point above 32 degrees F'. The use of the fuel is not stated. Obviously, electric vehicles do not use liquid fuel for propulsion, but some of them do use a small amount of liquid fuel in their heating systems. Standard No. 301 would apply to an electric vehicle with a fuel-fired heating system. With respect to Standard No. 102 Transmission Shift Lever Sequence, Starter Interlock, and Transmission Braking Effect, you ask for 'a clarification of this standard with regard to single speed transmissions' and, if it is applicable, ask that S3.1.3 'be rewritten or interpreted to include the initial activation of EV motor controllers as well as engine starters.' NHTSA has previously concluded that electric vehicles with single speed transmissions are excluded from Standard No. 102 (58 FR at 4646). I enclose a copy of the Federal Register notice reflecting this conclusion. Sincerely, Philip R. Recht Chief Counsel Enclosure"; |
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ID: aiam1435OpenMr. D. L. Massy, Chief Engineer, American Snowblast Corporation, 4695 Ironton Street, Denver, CO 80239; Mr. D. L. Massy Chief Engineer American Snowblast Corporation 4695 Ironton Street Denver CO 80239; Dear Mr. Massy: This responds to your March 4, 1974, question whether your rotar snowplows, constructed with four-wheel drive and four-wheel steer and a top speed of 35 miles per hour, must be certified to conform to Federal motor vehicle safety standards. You also asked whether 'certified brakes' will be sufficient certification to Standard 121, what the effects of a locked transfer case are on an anti-lock system, and what procedure exists to petition for an exemption from the standard.; I have enclosed an information sheet which explains that the vehicle you build for highway use are motor vehicles subject to the standard. The standard applies to the performance of the vehicle as a whole, not just to the brake system. In the event that the vehicles as completed do not actually comply, it is the manufacturer of the vehicle who is responsible.; I have enclosed a copy of the law and regulations explaining the basi for and necessary procedures to apply for a temporary exemption from our safety standards.; With regard to a locked transfer case, S6.1.11 of the air brak standard requires:; >>>S6.1.11 *Special drive conditions*. A vehicle equipped with a interlocking axle system or a front wheel drive system that is engaged and disengaged by the driver is tested with the system disengaged.<<<; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam3408OpenMr. 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 concerning S6.2.4 of Standard No 213, *Child Restraint Systems*. You asked whether section 5.2(d)(1) of Standard No. 209 is the relevant section to be used in testing the release force on buckles used on a child restraint system. The answer is yes.; Section 6.2 of Standard No. 213 sets out the test procedure fo measuring the release force for buckles used in child restraint systems. Section 6.2.4 states that the buckle is to be operated in the manner described in section 5.2(d) of Standard No. 209, Seat Belt Assemblies. S5.2(d)(1) of Standard No. 209 sets out the procedure for measuring the buckle release force. You are correct that S5.2(d)(2) and (3) set out the procedures for conducting several other requirements of Standard No. 209 which do not apply to child restraints and thus are not relevant to the buckle release force test.; If you have any further questions, please let me know. Sincerely, Frank Berndt, 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.