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
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ID: aiam3715OpenMr. S. Robson, Sr. Project Engineer - Vehicle Regulations, Mack Trucks, Inc., P.O. Box 1761, Allentown, PA 18105; Mr. S. Robson Sr. Project Engineer - Vehicle Regulations Mack Trucks Inc. P.O. Box 1761 Allentown PA 18105; Dear Mr. Robson: This responds to your recent letter requesting an interpretatio concerning the test procedures of Safety Standard No. 207. You ask whether a seat in a heavy duty truck must remain in its adjusted position when tested with a load of 20 times the weight of the entire seat, if the seat has been tested and remains in its adjusted position when subject to a load of 20 times the weight of the adjustable upper section of the seat.; This question arises because of the configuration of some heavy-dut truck seats which include suspension fixtures (pedestal structures) on which the upper seat section rests. Safety Standard No. 207 requires seats to withstand a load equal to 20 times their weight and requires the seats to remain in their adjusted position during the requried loading (paragraph S4.2). The upper seat sections and adjusters of your truck seats are tested on rigid test beds by the seat manufacturer and reportedly comply with the adjuster provision of S4.2. However, when you test these seats in the actual vehicle (applying 20 times the weight of the entire seat, including pedestal), the center of gravity falls on the seat adjuster and the seat does not always stay in its adjusted position during loading.; The answer to your specific question, the seat must remain in it adjusted position when tested to 20 times the weight of the entire seat, as required by paragraph S4.2 of the standard. We would agree with you, however, that with a seat configuration such as you describe, the adjusters and upper seat section would never experience a loading of 20 times the weight of the *entire* seat in an actual crash. Your problem appears to arise because the center of gravity of this seat happens to fall on the seat adjusters and the standard requires the loading to be applied through the center of gravity. The purpose of this loading requirement, however, is to ensure the integrity of the entire seat as it is attached to the vehicle structure.; Therefore, it is our opinion that for a pedestal seat such as yo describe, a manufacturer could establish due care through a combined test procedure which would load the seat adjusters and upper seat section to only 20 times the weight of those components to determine if the seat would remain in its adjusted position, and which would load the seat as anchored to the vehicle structure to 20 times the weight of the entire seat, including the pedestal. Please contact Hugh Oates of my staff if you have any further questions (202-426-2992).; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam0990OpenMr. Jacob G. Kassab, Secretary of Transportation, Commonwealth of Pennsylvania, Harrisburg, PA 17120; Mr. Jacob G. Kassab Secretary of Transportation Commonwealth of Pennsylvania Harrisburg PA 17120; Dear Mr. Kassab: This is in reply to your letter of December 27, 1972, concerning th absence from Motor Vehicle Safety Standard No. 208 of requirements for seat belts after the passive restraint requirements become effective.; Our aim in the last three years has been to improve the protectiv capabilities of the automobile so that it will automatically protect its occupants from serious injury and death. We do not intend in the least to disparage seat belts--to the contrary, we are making every effort to encourage their use. However, as passive restraints are installed, the marginal benefits to be gained from belts do not appear to be great enough to justify keeping them as required equipment.; The impacts that particularly concern you-- those occurring between 9 degrees and 270 degrees--are partially covered by the lateral impact test of Standard 208. Impacts in which the force is more nearly rearward are the subject of continuing investigation by our Research Institute, with a view toward possible improvements in the rear-end structure. If standards are proposed concerning rear impact protection, they will probably focus on improved seat structure or on rear-end modifications rather than on seat belts.; We think the course we are following will result in significantl increased protection for the motoring public.; Sincerely, Douglas W. Toms, Administrator |
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ID: aiam1682OpenMr. A.J. Burgess,Vice President (Technical),Joseph Lucas North America Inc.,Two Northfield Plaza,Troy, Michigan 48084; Mr. A.J. Burgess Vice President (Technical) Joseph Lucas North America Inc. Two Northfield Plaza Troy Michigan 48084; Dear Mr. Burgess:#This is to confirm your telephone conversation o November 13, 1974, with Mark Schwimmer of this office, concerning your request of October 4 for an interpretation of Federal Motor Vehicle Safety Standard No. 106-74 and its relation to SAE Standard J1403.#You are correct in assuming that all inside diameters listed in Tabled V and VI of Standard No. 106-74 are permitted for both light-wall and heavy-wall vacuum brake hose.#Section 103(d) of the National Traffic and Motor Vehicle Safety Act of 1966 prohibits any State from establishing or continuing in effect a safety standard applicable to an item of motor vehicle equipment performance, where there is an applicable Federal standard covering the same aspect of performance, unless the standards are identical. The NHTSA has determined that FMVSS 106-74 and SAE Standard J1403 are applicable to the same aspect of performance, and that they are not identical. Therefore, the States are prohibited from disapproving the use of brake hose which meets the requirements of Standard no. 106-74 but does not meet SAE Standard J1403.#Yours truly,Richard B. Dyson,Acting Chief Counsel; |
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ID: aiam4480OpenMr. A. L. Bragg Laboratory Manager Truck-Lite Co., Inc. 310 East Elmwood Avenue Falconer, NY 14733; Mr. A. L. Bragg Laboratory Manager Truck-Lite Co. Inc. 310 East Elmwood Avenue Falconer NY 14733; Dear Mr. Bragg: This is in reply to your letter of June 22, l988, t Mr. Vinson of this Office asking for an interpretation of Motor Vehicle Safety Standard No. 108. It is your understanding that for purposes of measuring the effective projected illuminated area of a lens, the reflex area, if any, must be subtracted from the total lens area. Your company manufactures a combination lamp which 'has four square inches of reflector area and eight square inches of stop, tail and turn area.' You have asked if you may advise your customers that this lamp may be used on vehicles whose overall width is 80 inches or more: 'A) Singularly (that is one on each side of the vehicle in the rear) as a stop, turn, tail and reflex reflector? B) In combination of two's or three's (on each side of the rear of the vehicle), provided that the lamps are separated by at least twenty-two inches?' Your understanding is correct, that the effective projected illuminated lens area must be determined without reference to any reflex reflector that may be combined with it. If the turn signal function in your lamp is met by one compartment, your lamp is acceptable under 'A).' But if the turn signal function is met by more than one compartment, your lamp would not be acceptable as the area of each compartment is less than l2 square inches. With regard to 'B),' the lamps could be used in combinations of twos and threes if they are mounted more than 22 inches apart but could not be used if mounted closer than 22 inches. You also asked about the relationship to paragraph S4.1.1.7. This paragraph covers replacement equipment only, without reference to its location on a vehicle. It applies only to turn signal lamps intended to replace original equipment turn signal lamps on vehicles manufactured in accordance with SAE Standard J588d, June l966. The current original equipment requirement is SAE Standard J588e September l970. You should be aware that the Truck Safety Equipment Institute has petitioned for rulemaking the effect of which would be to extend the l2-inch requirement to lamps used on all wide vehicles without reference to the 22-inch spacing. At present the agency is reviewing this petition. I hope that this answers your questions. Sincerely, Erika Z. Jones Chief Counsel; |
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ID: aiam1378OpenHonorable Charles H. Percy, United States Senate, Washington, DC 20015; Honorable Charles H. Percy United States Senate Washington DC 20015; Dear Senator Percy: This is in reply to your communication of January 3, 1974, forwardin to us correspondence dated November 29, 1973, from Mr. Bruce Motyka of Des Plaines. Mr. Motyka requests information regarding laws relating to pickup truck and camper weight limits, laws or studies relating to the sale of trucks exceeding GVW (Gross Vehicle Weight) rate minimums, and regulations or studies regarding maximum weights for tires.; The NHTSA has issued regulations relating to the installation o campers onto pickup trucks. Motor Vehicle Safety Standard No. 126 'Truck camper loading' (49 CFR S 571.126) requires each camper to bear a permanent label containing information on its maximum loaded weight. The standard also requires each camper to be furnished with an owner's manual that contains information on total camper weight, the selection of an appropriate pickup truck, appropriate methods of camper loading, how to determine the camper's center of gravity and where it should be placed in the truck cargo area. A companion 'Consumer Information' regulation, 'Truck camper loading' (49 CFR S 575.103) requires that written information be provided at the sale of each truck capable of being equipped with a slide-in camper that deals with the correct installation of a slide-in camper in that vehicle. This information is also required to be available in dealers' showrooms for retention by prospective purchasers of such trucks.; Other NHTSA regulations (49 CFR Part 567, 'Certification') requir every motor vehicle, including pickup trucks, to be labeled, usually on the driver's door or door jam, with its gross vehicle weight rating, and the gross axle weight rating for each axle. Each of these ratings is intended to be based on the weight of a fully loaded vehicle, as determined by the vehicle's manufacturer. While it is possible for manufacturers proposed course of action appears to have the aim of generating dissatisfaction with Federal tire regulations among dealers and distributors, and could, by lessening cooperation at the retail level, interfere with your client's ability to fulfill its obligations under the regulations.; Sincerely, Frank Berndt, Acting Chief Counsel |
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ID: aiam3345OpenMr. Bruce Henderson, Automobile Importers of America, Inc., 1735 Jefferson Davis Highway, Suite 1002, Arlington, Virginia 22202; Mr. Bruce Henderson Automobile Importers of America Inc. 1735 Jefferson Davis Highway Suite 1002 Arlington Virginia 22202; Dear Mr. Henderson: This responds to your September 4, 1980 letter to this office in whic you requested confirmation that a certain tire size was listed for use with a particular rim size in a tire publication recognized by this agency for purposes of Standard 110. Page 1-11 of the 1980 Yearbook of the Tire & Rim Association lists a 5 1/2 inch rim as appropriate for use with 185/70R14 tires. Thus, use of the 5 1/2 inch rims with that size tire would satisfy the requirements of paragraph S4.4.1(a) of Standard 110.; If you have any further questions or concerns regarding this matter feel free to contact Stephen Kratzke of my staff.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam2942OpenMr. D. K. Haenchen, Administrator, Vehicle Regulations, Volkswagen of America, 27621 Parkview, Boulevard, Warren, MI 48092; Mr. D. K. Haenchen Administrator Vehicle Regulations Volkswagen of America 27621 Parkview Boulevard Warren MI 48092; Dear Mr. Haenchen: This is in reply to your letter of January 3, 1979, asking fo confirmation of your interpretation of Federal Motor Vehicle Safety Standard No. 108 as it applies to a braking system that Volkswagen proposes to use on its 1980 Dasher model.; Specifically, the Dasher will employ a single 'pressure switch on eac vehicle, meaning that the stop lamp will be activated by only one of the [two, split] service brake systems.' You asked whether this is consistent with S4.5.4 of Standard No. 108 which requires that 'the stop lamps on each vehicle shall be activated upon application of the service brakes.' You argued that it meets the standard because:; >>>'Neither FMVSS 571.105-75 nor 575.108 (sic) clearly specify th conditions under which the stop lights have to operate. Specifically, the regulations do not specify that the stop lamps must illuminate upon application of the service brake control if one of the circuits of a dual circuit hydraulic braking system failed.'<<<; We do not concur with your interpretation. S4.5.4 quite clearl specifies the conditions under which the stop lamps must operate--'upon application of the service brakes,' and it is immaterial which circuit of a dual circuit hydraulic braking system is braking the vehicle. Therefore, your proposed system would constitute an apparent noncompliance with Standard No. 108.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam3650OpenMr. Robert B. Wessel, Consus International, Inc., P.O. Box 594, Port Jefferson Station, NY 11776; Mr. Robert B. Wessel Consus International Inc. P.O. Box 594 Port Jefferson Station NY 11776; Dear Mr. Wessel: This is in response to your December 1, 1982, letter regarding warning device you plan to manufacture. The device is powered by 4 AA batteries, and has a light which can stay on continuously or can flash. You have asked whether the device complies with Federal Motor Vehicle Safety Standard 125.; Standard 125 applies to warning devices 'without self- contained energ sources.' The four batteries in your device which power the light would constitute such a source. Therefore, Standard 125 is inapplicable to your device.; If you have further questions on this matter, feel free to contact us. Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam4195OpenMr. Andrew A. Kroll, 1401 East Girard, 207, Englewood, Colorado 80110; Mr. Andrew A. Kroll 1401 East Girard 207 Englewood Colorado 80110; Dear Mr. Kroll: This responds to your letter requesting an interpretation of Standar No. 109, *New Pneumatic Tires - Passenger Cars* (49 CFR S571.109). Specifically you asked whether that standard is applicable to foam-filled passenger car tires that do not have any air in the inner tire cavity. Standard No. 109 does not apply to foam-filled passenger car tires.; Section S2 of Standard No. 109 specifies that '[t]his standard applie to new pneumatic tire for use on passenger cars manufactured after 1948.' In section S3 of the standard, the term 'pneumatic tire' is defined as 'a mechnaical(sic) device made of rubber, chemicals, fabric and steel or other materials, which, when mounted on an automotive wheel, provides the traction and *contains the gas or fluid that sustains the load*' (emphasis added). Thus the relevant question is whether the foam filling the tires in question is considered a 'gas or fluid'. In a February 14, 1975 letter to Mr. J. F. Hutchinson, NHTSA stated that foam-filled tires 'should not be considered pneumatic tires.' This conclusion means that foam-filled tires for use on passenger cars are *not* subject to the requirements of Standard No. 109.; One result of this determination is that foam- filled tires can *not be installed as original equipment on any new passenger car. Standard No. 110, *Tire Selection and Rims* (49 CFR S571.110) sets forth requirements for new passenger cars. Section S4.1 of Standard No. 110 reads as follows: 'Passenger cars shall be equipped with tires that meet the requirements of S571.109.' Since foam-filled tires are not subject to Standard No. 109, they are still 'item of motor vehicle equipment' within the meaning of section 102(4) of the National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1391(4)). Among other things, this means that, if there is a determination that the tires contain a defect related to motor vehicle safety, the manufacturer of the foam-filled tires is required to notify purchasers and dealers of the defect and remedy the defect without charge to the purchasers, if the tire was purchased less than 3 calender years before the determination of defect was made.; If you have any further questions on this subject or need mor information, please contact Steve Kratzke of my staff at this address or by telephone at (202) 426-2992.; Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam1397OpenMr. J. Alec Reinhardt, Assistant Secretary and Attorney, White Motor Corporation, 100 Erieview Plaza, Cleveland, OH 44114; Mr. J. Alec Reinhardt Assistant Secretary and Attorney White Motor Corporation 100 Erieview Plaza Cleveland OH 44114; Dear Mr. Reinhardt: This is in response to your letter of February 4, regarding th proposed owner defect notification letter for defect notification campaign No. 73-0140.; Your letter fails to conform to 49 CFR, Part 577 as it states in th second sentence that the defect exists in equipment items manufactured and supplied by Rockwell International Corporation. We do not consider this statement to be responsive to 577.4(b)(1). As White Motor Corporation is the manufacturer of the motor vehicles involved, its determination and the statement required pursuant to 577.4(b)(1) must be to the effect that it has determined that a defect exists in the vehicles you identify in the following sentence.; The wording used by White Motor Corporation in the owner letter fo defect notification campaign No. 73-0242 is an example of a letter which does conform to the regulation.; The National Highway Traffic Safety Administration (NHTSA) is awar that there is a disagreement between White Motor Corporation and Rockwell International as to the exact cause of the defect. The NHTSA does not wish to become a party to this disagreement and in our opinion we cannot allow White Motor Corporation to use the owner notification letter as a forum to air their views.; I trust that you will make the appropriate changes to the owne notification letter and submit a revised copy to this office.; Sincerely, Andrew G. Detrick, Acting Director, Office of Defect Investigation, Motor Vehicle Programs; |
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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.