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: aiam2948OpenMr. Leon Conner, P.O. Box 1671, San Angelo, TX 76902; Mr. Leon Conner P.O. Box 1671 San Angelo TX 76902; Dear Mr. Conner: We understand that a question has arisen concerning the testing o 'P-type' tires under the traction grading procedures of the Uniform Tire Quality Grading (UTQG) Standards (49 CFR 575.104(f)(2)). Under the terms of the regulation, candidate tires are to be inflated to 24 psi prior to the traction test (49 CFR 575.104(f)(2)(i)(B) and (D), and (f)(2)(viii)), and are to be loaded to 85 percent of the load specified in Appendix A of FMVSS No. 109 (49 CFR 571.109), for the tires' size designation, at a cold inflation pressure of 24 psi (49 CFR 575.104(f)(2)(viii)). However, Appendix A lists cold inflation pressures for 'P-type' tires in kilopascals, with no stated inflation pressure corresponding precisely to 24 psi.; NHTSA chose 24 psi as the stated inflation pressure for UTQG tractio testing since it represents the recommended tire inflation pressure for most passenger cars. In the situation where no cold inflation pressure exactly equivalent to the specified pressure of 24 psi is stated in Appendix A of FMVSS No. 109 for a tire size designation, the tires to be tested are inflated to the pressure, listed for the tire size designation in Appendix A, which is nearest to 24 psi, *i.e.*, 180 kPa for tires with inflation pressures measured in kilopascals. The tires are then loaded to 85 percent of the load specified in Appendix A for the inflation pressure thus determined. The agency plans to issue an interpretive amendment to the regulation clarifying this point.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam4832OpenMr. Billy S. Peterson President Automotive Safety Testing, Inc. at TRC of Ohio, Bldg. 20 Rd. 152 & SR 33 East Liberty, OH 43319; Mr. Billy S. Peterson President Automotive Safety Testing Inc. at TRC of Ohio Bldg. 20 Rd. 152 & SR 33 East Liberty OH 43319; Dear Mr. Peterson: This is in reply to your letter of February 7, l99l to the Office of Chief Counsel asking for a clarification of allowable mounting locations and photometric output requirements for tail/stop lamps on passenger cars. One of your clients wishes to mount 'two-part' stop/tail lamps 'so that one lamp is mounted on the fixed quarter panel and a duplicate lamp is mounted on the trunk lid.' Each part of the two-part lamp is a combination tail/stop lamp. You have asked whether the minimum photometric requirements must be met by 'the lamp mounted to the quarter panel or may the portion mounted on the trunk lid count toward the photometric requirements.' Your 'two-part lamp' would be treated as two separate lamps. For purposes of compliance, only one of these two adjacent lamps must be designed to conform to Standard No. 108, and this conformance must be independent of any 'contribution' by the adjacent lamp. Although Standard No. 108 permits either the deck or the body mounted lamp to be the complying lamp, it would be our preference that the body mounted lamp be the one that complies, so that the benefit of a conforming stop/tail lamp would be realized during those occasions when the lid may be raised. Sincerely, Paul Jackson Rice Chief Counsel; |
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ID: aiam1563OpenMr. Jack R. Gilstrap, General Manager, Southern California Rapid Transit District, 1060 South Broadway, Los Angeles, CA, 90015; Mr. Jack R. Gilstrap General Manager Southern California Rapid Transit District 1060 South Broadway Los Angeles CA 90015; Dear Mr. Gilstrap: This is in reply to your letter of July 17, 1974, asking whether S4. of Standard No. 108 prohibits a bus manufacturer from installing wiring that could later be connected by the purchaser to normally steady-burning clearance lamps, enabling them to be flashed to signal a crime in progress. The vehicle modifications here concerned are the installation both of certain wiring by General Motors and dual filament bulbs in each clearance lamp by the Southern California Rapid Transit District.; Paragraph S4.6 requires that signalling lamps specified in Standard No 108 shall flash when activated, and that 'all other lamps' shall be steady-burning. Paragraph S4.1.3 in part prohibits the installation of motor vehicle equipment that impairs the effectiveness of the lighting equipment required by Standard No. 108.; We construe the phrase 'all other lamps' in S4.6(b) to mean lamps tha are required by Standard No. 108. Supplemental lamps on ambulances and police cars, for example, that flash in normal use are not included in the standard. Similarly, it would appear that when the clearance lamp you discuss is operated as a warning lamp it becomes an item of lighting equipment outside the coverage of Standard No. 108. Therefore the fact that it flashes when activated would not violate the intent of S4.6(b). Similarly, the wiring that is installed by GM is not considered additional equipment that impairs the effectiveness of the required equipment.; The modifications you described, therefore, are not prohibited b Standard 108.; Yours truly, Richard B. Dyson, Acting Chief Counsel |
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ID: aiam4915OpenWilliam Engel, Assistant Chief Covington Fire Department 100 E. Robbins St. Covington, KY 41011; William Engel Assistant Chief Covington Fire Department 100 E. Robbins St. Covington KY 41011; "Dear Mr. Engel: This responds to your letter asking whether Federa Motor Vehicle Safety Standard No. 206, Door Locks and Door Retention Components, requires door locks on fire trucks. Safety Standard No. 206, which applies to all passenger cars, multipurpose passenger vehicles and trucks, does not exclude fire trucks. Thus, new fire trucks are covered by the standard's general requirement that 'components on any side door leading directly into a compartment that contains one or more seating accommmodations shall conform to this standard.' S4 Standard No. 206 does not apply, however, to certain types of doors which are often found on fire trucks. Since your letter did not provide any details about the design of the specific doors to which you refer, I am unable to determine whether any of the doors on those fire trucks would be subject to Standard No. 206's requirements. For your information, I have enclosed two letters from this office which discuss the applicability of Standard No. 206 to specific doors on fire trucks in more detail. The two letters are an August 13, 1980 letter to Mr. Steenbock and a February 11, 1988 letter to Ms. Salvio. The National Highway Traffic Safety Administration has not adopted any amendments to Standard No. 206 that affect the accuracy of the information contained in these letters. I have also enclosed a current copy of Standard No. 206. I hope this information is helpful. Please contact Elizabeth Barbour of my staff at this address or by telephone at (202) 366-2992 if you have further questions. Sincerely, Paul Jackson Rice Chief Counsel Enclosures"; |
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ID: aiam1906OpenBenjamin Sachs, M.D., Associate Director, Division of Local Health Services, Room 360, Massachusetts Department of Public Health, 600 Washington Street, Boston, MA 02111; Benjamin Sachs M.D. Associate Director Division of Local Health Services Room 360 Massachusetts Department of Public Health 600 Washington Street Boston MA 02111; Dear Dr. Sachs: In response to your request of April 4, 1975, I am enclosing a copy o Federal Motor Vehicle Safety Standard No. 208, several *Federal Register* notices which have modified the basic standard, and the Motor Vehicle and Schoolbus Safety Amendments of 1974. Also enclosed is a circular explaining how all the safety standards and regulations of the National Highway Traffic Safety Administration (NHTSA) may be obtained.; Until October 29, 1974, section S4.1.2 of the standard required a ignition interlock on 1974- and 1975-model passenger cars. As noted in the enclosed amendment (Docket 74-39, Notice 1), recent legislation mandated the deletion of this requirement, which was accomplished by NHTSA on October 29, 1974.; Manufacturers may now meet Standard No. 208 by providing (1) lap an shoulder belts at front outboard positions and lap belts at other positions, and (2) a continuous or flashing reminder light that operates only during the 4- to 8-second period after the ignition is operated and a continuous or intermittent audible warning signal which operates only during the 4- to 8-second period after the ignition is operated if the driver's lap belt is not in use. They may also provide certain types of 'passive restraint' devices in place of the seat belt assemblies.; Although the seat-belt interlock system is not prohibited, it is n longer a means of complying with the standard.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam2081OpenHonorable Barber B. Conable, Jr., House of Representatives, Washington, DC 20515; Honorable Barber B. Conable Jr. House of Representatives Washington DC 20515; Dear Mr. Conable: This is in response to your letter of September 5, 1975, requestin information concerning an inquiry from one of your constituents, Mr. F. J. Guppenberger, relating to the permissibility of raising cars' rear bumpers.; Motor Vehicle Safety Standard No. 215, *Exterior Protection*, impose performance requirements on automobile bumper systems. One of these requirements specifies impacts at certain heights, and has the effect of requiring bumpers to be manufactured at fairly uniform heights.; The National Traffic and Motor Vehicle Safety Act (Pub. L. 89-563), a recently amended (Pub. L. 93-492), prohibits any manufacturer, distributor, dealer, or motor vehicle repair business from knowingly rendering inoperative, in whole or in part, any device or element of design installed on or in a motor vehicle or item of motor vehicle equipment in compliance with an applicable motor vehicle safety standard (S 108(a) (2) (A)). Therefore, if the bumper were raised by one of the above classes of persons causing it no longer to comply with the Standard No. 215 requirements, a violation of the Act would have occurred. That law does not, however, prohibit an individual from altering the bumper on his own car.; The National Highway Traffic Safety Administration, the agency tha administers the Traffic Safety Act, is not authorized by that Act to prohibit vehicles with raised bumpers from operating on the highways. Except for certain limited areas such as motor carriers in interstate commerce, the regulation of vehicles operating on the highways is within the authority of the States.; Sincerely, William T. Coleman, Jr. |
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ID: aiam4913OpenWilliam Engel, Assistant Chief Covington Fire Department 100 E. Robbins St. Covington, KY 41011; William Engel Assistant Chief Covington Fire Department 100 E. Robbins St. Covington KY 41011; "Dear Mr. Engel: This responds to your letter asking whether Federa Motor Vehicle Safety Standard No. 206, Door Locks and Door Retention Components, requires door locks on fire trucks. Safety Standard No. 206, which applies to all passenger cars, multipurpose passenger vehicles and trucks, does not exclude fire trucks. Thus, new fire trucks are covered by the standard's general requirement that 'components on any side door leading directly into a compartment that contains one or more seating accommmodations shall conform to this standard.' S4 Standard No. 206 does not apply, however, to certain types of doors which are often found on fire trucks. Since your letter did not provide any details about the design of the specific doors to which you refer, I am unable to determine whether any of the doors on those fire trucks would be subject to Standard No. 206's requirements. For your information, I have enclosed two letters from this office which discuss the applicability of Standard No. 206 to specific doors on fire trucks in more detail. The two letters are an August 13, 1980 letter to Mr. Steenbock and a February 11, 1988 letter to Ms. Salvio. The National Highway Traffic Safety Administration has not adopted any amendments to Standard No. 206 that affect the accuracy of the information contained in these letters. I have also enclosed a current copy of Standard No. 206. I hope this information is helpful. Please contact Elizabeth Barbour of my staff at this address or by telephone at (202) 366-2992 if you have further questions. Sincerely, Paul Jackson Rice Chief Counsel Enclosures"; |
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ID: aiam4125OpenMr. Bob Carlson, 8305 29th Avenue, N.W., Seattle, WA 98117; Mr. Bob Carlson 8305 29th Avenue N.W. Seattle WA 98117; Dear Mr. Carlson: This responds to your January 23, 1986 letter inquiring about Federa motor vehicle safety standards applicable to your projected sale of aftermarket windshield wiper systems for trucks.; Under the National Traffic and Motor Vehicle Safety Act, this agenc has issued Federal Motor Vehicle Safety Standard No. 104, *Windshield Wiping and Washing Systems*, applicable to new motor vehicles. As you note, this standard applies to trucks, as well as other types of vehicles. In your letter, you ask which performance requirements apply to wiping systems for trucks.; Under S4. *Requirements*, new trucks are required to have power-driven windshield wiping system that meets the requirements of S4.1.1. The frequency requirements in S4.1.1 apply to trucks, but the wiped area requirements of S4.1.2 apply only to passenger cars. Trucks must also have a windshield washing system that meets the requirements of SAE Recommended Practice J942, November 1965, except that the 'effective wipe pattern' is considered to be 'the pattern designed by the manufacturer for the windshield wiping system on the exterior surface of the windshield glazing.' Therefore, the vehicle manufacturer establishes the wipe pattern of the system.; If a new truck equipped with your wiper system did not comply wit Standard No. 104 due to some aspect of that system, the sale of that truck to the public would be a violation of the prohibition in section 108(a)(1)(A) of the Act against the sale of noncomplying vehicles.; I hope this information is helpful to you. Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam4935OpenMr. John H. Heinrich District Director of Customs U.S. Customs Service 300 So. Ferry Street Terminal Island, CA 90731; Mr. John H. Heinrich District Director of Customs U.S. Customs Service 300 So. Ferry Street Terminal Island CA 90731; Re: Case No. 92-2704-00015 Dear Mr. Heinrich: This responds to you letter of December 5, 1991, enclosing a petition for relief from the forfeiture of '200 Spinner Wheel Nuts' seized by the Customs Service as violative of 49 CFR Sec. 571.211. The petitioner expresses the opinion that the wheel nuts should be exempt from DOT regulations, stressing safety considerations and the need to replace worn parts on vehicles manufactured in the l950's. You have also enclosed a copy of the petitioner's own parts list that identifies the wheel nuts as part of a conversion kit, intended to replace disc wheels with wire wheels. Federal Motor Vehicle Safety Standard No. 211, Wheel Nuts, Wheel Discs, and Hub Caps, 49 CFR 571.211, precludes, for use on passenger cars, wheel nuts that incorporate winged projections. The chrome wheel nuts depicted in the Moss Motors catalogue page which you enclosed (Parts Nos. 200-210 and 200-220) clearly incorporate winged projections, and are the type of wheel nuts that Standard No. 211 addresses and prohibits. As such, they may not be imported for sale in the United States. We have discounted petitioner's safety arguments. This is the first allegation in the nearly 24 years that the standard has been in effect that the spinners are required to replace original equipment, implying that there is no acceptable substitute that would conform with Standard No. 211. In our view, no justification has been shown for granting the petition. Sincerely, Paul Jackson Rice Chief Counsel; |
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ID: aiam4124OpenMr. Bob Carlson, 8305 29th Avenue, N.W., Seattle, WA 98117; Mr. Bob Carlson 8305 29th Avenue N.W. Seattle WA 98117; Dear Mr. Carlson: This responds to your January 23, 1986 letter inquiring about Federa motor vehicle safety standards applicable to your projected sale of aftermarket windshield wiper systems for trucks.; Under the National Traffic and Motor Vehicle Safety Act, this agenc has issued Federal Motor Vehicle Safety Standard No. 104, *Windshield Wiping and Washing Systems*, applicable to new motor vehicles. As you note, this standard applies to trucks, as well as other types of vehicles. In your letter, you ask which performance requirements apply to wiping systems for trucks.; Under S4. *Requirements*, new trucks are required to have power-driven windshield wiping system that meets the requirements of S4.1.1. The frequency requirements in S4.1.1 apply to trucks, but the wiped area requirements of S4.1.2 apply only to passenger cars. Trucks must also have a windshield washing system that meets the requirements of SAE Recommended Practice J942, November 1965, except that the 'effective wipe pattern' is considered to be 'the pattern designed by the manufacturer for the windshield wiping system on the exterior surface of the windshield glazing.' Therefore, the vehicle manufacturer establishes the wipe pattern of the system.; If a new truck equipped with your wiper system did not comply wit Standard No. 104 due to some aspect of that system, the sale of that truck to the public would be a violation of the prohibition in section 108(a)(1)(A) of the Act against the sale of noncomplying vehicles.; I hope this information is helpful to you. Sincerely, Erika Z. Jones, 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.