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: 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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ID: aiam4637OpenMr. Randy Blackman Per-Lux Inc. 1242 E. Edna Place Covina, CA 91724; Mr. Randy Blackman Per-Lux Inc. 1242 E. Edna Place Covina CA 91724; "Dear Mr. Blackman: This responds to your letter asking for informatio about the application of Federal safety standards to a head restraint that attaches to the rear window of pickup trucks. I hope the following information is helpful. By way of background information, the National Highway Traffic Safety Administration (NHTSA) is authorized by the National Traffic and Motor Vehicle Safety Act (the Safety Act) to issue Federal motor vehicle safety standards that set performance requirements for new motor vehicles and items of motor vehicle equipment. NHTSA is not authorized to certify or approve motor vehicles or motor vehicle equipment for compliance with our Federal motor vehicle safety standards. Instead, under the Safety Act (copy enclosed), each manufacturer of a motor vehicle or item of motor vehicle equipment is responsible for certifying that its products meet all applicable safety standards. The following represents our opinion based on our understanding of the information provided in your letter. There is currently no Federal motor vehicle safety standard that is directly applicable to the product you wish to manufacture and sell. Our standard for head restraints (Standard No. 202) applies only to completed new passenger cars and not to a head restraint device sold as an item of 'aftermarket' equipment for pickup trucks. However, there are other Federal requirements that indirectly affect your manufacture and sale of the head restraint device. Under the Safety Act, your device is considered to be an item of motor vehicle equipment. As a manufacturer of motor vehicle equipment, you are subject to the requirements in sections 151-159 of the Safety Act concerning the recall and remedy of products with defects relating to motor vehicle safety. I have enclosed an information sheet that briefly describes those responsibilities. In the event that you or NHTSA determines that your head restraints contain a safety related defect, you would be responsible for notifying purchasers of the defective equipment and remedying the problem free of charge. Safety Standard No. 302, Flammability of Interior Materials (copy enclosed), would also affect your head restraint if your product were installed by a commercial business on either new or used vehicles. A manufacturer installing your head restraint device on a new truck prior to certifying the truck as complying with all applicable Federal motor vehicle safety standards, as required by the Safety Act, has certain responsibilities relating to that obligation to certify. Standard No. 302 establishes flammability resistance requirements for trucks that must be met by certain vehicle components, including head restraints. The new vehicle manufacturer that installs your product on the new vehicle would have to certify the vehicle's compliance with Standard No. 302, and thus would be required to ensure that the head restraint device conforms to the flammability resistance requirements of the standard. A commercial business wishing to install the head restraint on new or used vehicles would be subject to statutory considerations that affect whether the business may install your product on a vehicle without violating the Safety Act. Section 108(a)(2)(A) of the Act states: 'No manufacturer, distributor, dealer, or motor vehicle repair business shall knowingly render inoperative ... any device or element of design installed on or in a motor vehicle or item of motor vehicle equipment in compliance with an applicable Federal motor vehicle safety standard ...' This section requires manufacturers, distributors, dealers or motor vehicle repair businesses (i.e., any person holding him or herself out to the public as in the business of repairing motor vehicles or motor vehicle equipment for compensation) installing your head restraint device on new or used vehicles to ensure that the addition of the apparatus would not negatively affect the compliance of any component or design on a vehicle with applicable Federal safety standards. For example, the commercial entity must ensure that the addition of the device does not degrade from the safety provided by flammable-resistant materials in the vehicle's interior compartment which have been installed in accordance with Standard No. 302. Installation of rapidly burning materials could vitiate the compliance of the materials which were present in the vehicle at the time of its sale to the first consumer and were certified as meeting FMVSS No. 302. Section 109 of the Act specifies a civil penalty of up to $1,000 for each violation of /108. However, the prohibitions of /108(a)(2)(A) do not apply to the actions of a vehicle owner in adding to or otherwise modifying his or her vehicle. Thus, a vehicle owner would not violate the Safety Act by installing the head restraint, even if doing so would negatively affect some safety feature in his or her vehicle. In addition to the materials described above, I am also enclosing a Federal Register notice (53 FR 50047) that NHTSA issued on December 13, 1988, proposing to extend the applicability of Standard No. 202 to light trucks and vans. NHTSA has proposed to make this extension effective September 1, 1991. We expect to announce the agency's next step in the rulemaking proceeding by this fall. We are also returning herewith the sketch you enclosed with your letter, as you requested in a telephone conversation with Ms. Fujita of my staff. We have issued this interpretation based on information which you confirmed you have no objection to publicly disclosing, and not on information which you asked us not to publicly disclose. Please feel free to contact us if you have further questions. Sincerely, Stephen P. Wood Acting Chief Counsel Enclosures"; |
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ID: aiam1065OpenMr. Bill Milby, Project Engineer, Blue Bird Body Company, Fort Valley, GA 31030; Mr. Bill Milby Project Engineer Blue Bird Body Company Fort Valley GA 31030; Dear Mr. Milby: This is in reply to your letter of March 16, 1973, requesting a interpretation of the words ...unobstructed openings for emergency exit which collectively amount in total square inches...' in S5.2 of Standard No. 217, Bus Window Retention and Release'.; We believe your paragraph stating, The area credited to an emergenc exit must be the clear opening less the projected area of any obstruction in front of the exit', to be an appropriate interpretation of the phrase. We do not believe that the existence of some obstruction prevents an otherwise unobstructed opening from being used to fulfill the requirements of paragraph S5.2. You are correct in stating that whether such a window is unobstructed can be determined by utilizing the ellipsoid specified in paragraph S5.4.; You indicate in your letter you believe that if your interpretatio were applied to school buses it would result in a significant loss of seating capacity. It does not appear to us, however, that the reduction of the area of the unobstructed opening by the projected area of the obstruction, as shown in your photograph, will be significant.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam3058OpenMr. D. K. Haenchen, Volkswagen of America, 7111 E. Eleven Mile Road, Warren, MI 48090; Mr. D. K. Haenchen Volkswagen of America 7111 E. Eleven Mile Road Warren MI 48090; Dear Mr. Haenchen: This is in response to your letter of March 19, 1979, regarding th photographic procedures, announced in Docket 73-19, Notice 24 (43 FR 40229, September 11, 1978), to be used by the National Highway Traffic Safety Administration (NHTSA) in evaluating shielding panel damage in compliance testing for the Part 581 *Bumper Standard* (49 CFR Part 581). You ask where the camera is located when taking the 45 degree angle photograph specified in Notice 24 under the heading Camera Position. You also ask where the three photoflood lamps specified in Notice 24 under the heading Illumination are positioned.; Where the plan of the shielding panel area under examination i nominally horizontal, NHTSA positions the camera and lamps relative to the vertical reference line running through the center of the suspect area. Where the plane of the shielding panel area is nominally vertical and perpendicular to the longitudinal center line of the vehicle, the camera and lamps will be positioned relative to the horizontal reference line running through the center of the suspect area, parallel to the vehicle's longitudinal center line. Where the plane of the suspect area is nominally vertical and parallel to the longitudinal center line of the vehicle, the camera and lamps are positioned relative to the horizontal reference line running through the center of the suspect area, perpendicular to the vehicle's longitudinal center line.; In taking the 90 degree angle photograph, NHTSA positions the camera o the reference line so that the foremost point of the camera lens is six feet from the point at which the reference line intersects the surface of the suspect area (point S). In taking the 45 degree angle photograph, NHTSA positions the camera on a line which intersects the reference line at a 45 degree angle at point S, and which lies in a vertical plane containing the reference line. Where the reference line is vertical, the camera is positioned on a line which lies in a plane parallel to the vehicle's longitudinal center line. The camera is positioned so that the foremost point of the camera lens is six feet from point S. A camera position is chosen which provides an unobstructed view of the suspect area.; The two main photoflood lamps are positioned facing the exterio surface of the suspect area with the filament of each lamp ten feet from point S. Except where the reference line is vertical, the two main lamps are positioned in the horizontal plane containing point S, on opposite sides of the vertical plane containing the reference line, so that the lines connecting the lamp filaments with point S form a 45 degree angle with the reference line.; Where the reference line is vertical, the two main lamps are positione in the vertical plane containing point S which is perpendicular to the vehicle's longitudinal center line. The lamps are positioned on opposite sides of the vertical plane containing point S which is parallel to the vehicle's longitudinal center line, so that the lines connecting the lamp filaments with point S form 45 degree angles with the reference line.; NHTSA has determined that the third photoflood lamp described in Notic 24, to be employed for fill-in lighting, is unnecessary and this lamp is not used by the agency.; 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.