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: aiam2691OpenHonorable Hamilton Fish, Jr., House of Representatives, Washington, DC 20515; Honorable Hamilton Fish Jr. House of Representatives Washington DC 20515; Dear Mr. Fish: This is in response to your letter of August 24, 1977, forwardin correspondence from one of your constituents, Mr. Richard G. Castor, concerning an automobile accident in which he was involved.; Mr. Castor stated that he was involved in a 30 mph collision with pole, which caused considerable damage to his car. He suggested that a poorly designed bumper was responsible for the severity of the damage to his automobile.; The accident described by Mr. Castor occurred at a speed far above tha involved in the typical low speed 'fender bender' accident. If his 30 mph impact estimate is accurate it is remarkable that he was not injured and that the vehicle was capable of being repaired. No motor vehicle bumper of reasonable size and weight could possibly protect a vehicle from damage in such a high speed collision.; The National Highway Traffic Safety Administration (NHTSA) has had i effect since 1974 a safety standard that requires cars to be capable of sustaining 5 mph impacts, front and rear, without suffering damage to their various safety systems. That standard was promulgated pursuant to the National Traffic and Motor Vehicle Safety Act of 1966 (Pub. L. 89-563). The Motor Vehicle Information and Cost Savings Act of 1972 (Pub. L. 92-513) directed the agency to promulgate a bumper standard that would reduce the costs to consumers occasioned by low-speed collisions. In response to that order, the NHTSA established a standard that would prohibit damage both to safety systems and to all other surface areas of vehicles involved in low-speed collisions.; Under that standard (49 CFR Part 581, *Bumper Standard*), effectiv September 1, 1978, cars will be permitted to sustain damage only to the bumper itself when subjected to 5 mph front and rear impacts. Thirty mile- per-hour protection was not envisioned by Congress and would so increase the cost and weight of a vehicle as to make its purchase and operation unfeasible.; Your constituent's comments are appreciated. Sincerely, Joan Claybrook |
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ID: aiam1117OpenMr. Phillip P. Friedlander, Jr., Director of Communication, National Tire Dealers & Retreaders Association, Inc., 1343 L Street, N.W., Washington, D.C. 20005; Mr. Phillip P. Friedlander Jr. Director of Communication National Tire Dealers & Retreaders Association Inc. 1343 L Street N.W. Washington D.C. 20005; Dear Mr. Friedlander: This is in reply to your letter of March 21, 1973, in which you ask ho retreaded tires are to be tested to the strength requirements (plunger-energy) of Standard No. 117 (S5.1.1, incorporating by reference S4.2.2.4 of Standard No. 109). You appear to believe testing to the requirement is precluded because Standard No. 117 contains no requirement that the cord material be labeled onto the tire, and the plunger-energy requirements specify different performance levels for differing cord materials.; While Standard No. 117 does not require the generic name of the cor material to be labeled onto the retreaded tire, we expect that it will be found on most tire casings and will be available to the retreader on all post 'DOT' casings, and on many pre-DOT casings as well. If a retreader tire is not labeled with its cord material, the strength test can still be conducted. It is not necessary to know the cord material before the plunger-energy values are obtained. Once they are obtained, a sample can be removed from the tire, from which the material can be determined.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam4315OpenMr. L.T. Mitchell, Specification Engineer, Thomas Built Buses, L.P., P. O. Box 2450, 1408 Courtesy Road, High Point, NC 27261; Mr. L.T. Mitchell Specification Engineer Thomas Built Buses L.P. P. O. Box 2450 1408 Courtesy Road High Point NC 27261; Dear Mr. Mitchell: This responds to your letter to me regarding the questions you shar with the Connecticut Department of Motor Vehicles (DMV) about paragraph S5.1.2 of Standard No. 222, *School Bus Passenger Seating and Crash Protection.* I regret the delay in our response. As you know, your letter was supplemented by information we received in a letter from Mr. Harry Gough of the DMV. We have also incorporated into your inquiry information you provided on February 26 to Mr. Paliokas of NHTSA's Office of Vehicle Safety Compliance concerning the dimensions of the seat back in question. I regret the delay in this response.; The first question you ask is whether S5.1.2 applies to the last ro 'davenport' type seat found in a rear engine school bus. The answer is yes. By its terms, S5.1.2 applies to 'each school bus passenger seat' and makes no exception for the rearmost seat.; The second question you ask relates to the concerns you and the DM have about the requirements in S5.1.2 for seat back surface area. Because Connecticut prohibits the top of rear divan seats to be higher than the lower edge of rear emergency windows, the state wishes to reduce the height of the seat back on a seat located in the last row of the school bus and reduce the width of the seat cushion (to 29 inches) by use of 'spacers.' You enclosed a diagram of the seating design to illustrate how the proposal compares with your standard school bus seat and called the new seat 'cushion 2' and the area of its seat back 'area 2.' The DMV sent us a diagram showing the location of the spacers on cushion 2.; You believe that the DMV's desired seat back design would not compl with Standard No. 222 and ask us whether you have made a correct determination. As explained below, the answer is yes.; Paragraph S5.1.2 of Standard No. 222 regulates the height and surfac area of seat backs on school buses. It states:; >>>Each school bus passenger seat shall be equipped with a seat bac that, in the front project view, has a front surface area above the horizontal plane that passes through the seating reference point, and below the horizontal plane 20 inches above the seating reference point, of not less than 90 percent of the seat bench width in inches multiplied by 20.<<<; In order to ascertain the compliance with S5.1.2 of the seat back i question, the area of the seat back (in the front projected view) between the two horizontal planes referenced in S5.1.2 is calculated. To calculate this, dimensions are needed for the height of the seat back above the seating reference point (SRP) and the width of the seat back. The information you provided to Mr. Paliokas concerned the SRP and seat back height. According to that information and the diagram you enclosed, the seat back for cushion 2 is five inches lower than your standard school bus seat back. Thus, the height above the SRP of the seat back for cushion 2 is approximately 14.25 inches.; As to the width of the seat back, the question arises whether it shoul be considered to be 29 or 39 inches wide. While the seat back appears to be 39 inches wide in your illustration, the 'spacers' located on each end of the seat in front of the seat back reduce the seat width to 29 inches.; The use of the spacers brings up two related issues. First, are the adequate in rendering portions of the bench seat inappropriate for use as seating surface areas? You as the manufacturer must make a good faith determination of their adequacy. We do not have enough information at this time to answer this question, however, we will assume for the purposes of this discussion that the answer is yes.; Second, assuming that the spacers are adequate in making portions o the bench seat unlikely to be used for seating, should the surface of the seat back behind the spacers be considered part of the cushion 2's seat back surface area for purposes of S5.1.2? We believe the answer to this question is no. Since non-seating areas are not required to be compartmentalized between high seat backs or restraining barriers, we do not consider portions of a seat back behind non-seating positions as part of the seat back surface area required by S5.1.2 to be provided for school bus seats. Hence, if the spacers render cushion 2 into a 29 inch seat, we conclude that the width of the corresponding seat back is 29 inches.; Under S5.1.2, the front surface area of the seat back between the tw referenced planes must be not less than 90 percent of the seat bench width in inches multiplied by 20. The required surface area for a seat back of a 29 inch bench seat thus must be at least 522 square inches. Since the seat back for cushion 2 has a height above the SRP of 14.25 inches and a width of 29 inches, its area is only 413.25 square inches. Therefore, the seat back does not meet S5.1.2 of Standard No. 222.; In his letter to us, Mr. Gough argues that the proposed design woul not violate the purpose of Standard No. 222 since the seat back in question would be located in the rear of the school bus and no person would be sitting or standing behind it. We cannot accept this argument. Paragraph S2 of Standard No. 222 states: 'The purpose of this standard is to reduce the number of deaths and the severity of injuries that result from the impact of school bus occupants against structures within the vehicle during crashes and sudden driving maneuvers.' In accordance with this intent, Standard No. 222 requires school buses to comply with 'compartmentalization' requirements to provide passenger crash protection. To achieve the benefits of compartmentalization, it is important that passengers be protected and confined in the event of a crash within an area of sturdy, well-padded seats. The seat back area required by S5.1.2 is necessary, therefore, not only to provide protection to passengers seated behind the seat back, but also to ensure that the protective compartment is provided for occupants of the seat.; I hope this letter is helpful. I am sending a copy of this letter t Mr. Gough for his information. Please contact my office if you or he have further questions.; Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam1696OpenMr. Harold Dvorachek,Product Engineer,The Berg Manufacturing Company,333 East Touhy Avenue,Des Plaines, Illinois 60018; Mr. Harold Dvorachek Product Engineer The Berg Manufacturing Company 333 East Touhy Avenue Des Plaines Illinois 60018; Dear Mr. Dvorachek:#This responds to your letter of October 25, 1974 requesting an interpretation of Standard No. 106-74, *Brake hoses*, as it applies to the labeling of air brake hose end fittings which use sacrificial sleeves.#>>>S7.2 states:#In the case of an end fitting intended for use in a reuseable assembly, 'AI' or 'AII' shall indicate use with Type I or type II hose respectively.<<<#Since an end fitting which uses a sacrificial sleeve is defined by S4 to be a permanently attached end fitting, it does not fall into the classification 'End fitting[s] intended for use in a reuseable assembly.' Therefore, it must be labeled with the designation 'A' rather than any of the following: 'AI', 'AII', 'AI-AII'.#Yours truly,Richard B. Dyson,Acting Chief Counsel; |
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ID: aiam2813OpenMr. E. M. Ryan, Chief Design Engineer, Ward Industries, Inc., P.O. Box 849, Highway 65 South, Conway, AR 72032; Mr. E. M. Ryan Chief Design Engineer Ward Industries Inc. P.O. Box 849 Highway 65 South Conway AR 72032; Dear Mr. Ryan: This responds to your April 27, 1978, letter asking whether a sampl certification label that you submitted complies with the National Highway Traffic Safety Administration's (NHTSA) Part 567, *Certification*.; Military vehicles are exempted from compliance with Federal safet standards. Therefore, the application of the safety standards to these vehicles is a matter of contract between a manufacturer and the military. Since the NHTSA does not mandate Federal safety standards for these vehicles, it is not necessary to put certification labels on them. If you choose to include a label with a vehicle, the label would not be required to comply with any Federal regulations.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam3701OpenMr. Alberto Negro, Fiat Research & Development - USA Branch, Fiat Motors of North America, Inc., Parklane Towers West, Suite 1210, Dearborn, MI 48126; Mr. Alberto Negro Fiat Research & Development - USA Branch Fiat Motors of North America Inc. Parklane Towers West Suite 1210 Dearborn MI 48126; Dear Mr. Negro: This is in reply to your letter of May 9, 1983, to Mr. Vinson of m staff with respect to conformance of a planned stop lamp design with Federal Motor Vehicle Safety Standard No. 108, *Lamps, Reflective Devices, and Associated Equipment*.; The design comprises two compartments separated by a reflex reflector One of the compartments will meet the photometric requirements for a stop lamp, in your judgment. The other will not, but in conjunction with the first compartment 'the requirements can be met.' You have asked if this arrangement is acceptable pursuant to paragraph S4.1.1.6 which allows photometric requirements to be met by a combination of compartments or lamps.; Paragraph S4.1.1.6 is intended to cover replacement stop lamps fo vehicles manufactured between January 1, 1973, and September 1, 1978, when the SAE standard for stop lamps incorporated into Standard No. 108 was SAE J586b, September 1966. As such, its requirements are not relevant to your concerns.; However, SAE J586c, August 1970, whose requirements do apply to sto lamps, appears to permit your design. Under paragraph 3.1, where the distance between filament centers of two stop lamps does not exceed 22 inches (presumably your design) the photometric readings of both lamps must be combined to meet the photometric requirements of Table 1 of J586c applicable to two lighted sections. However, the combined candela must not exceed the specified total of 360 for two lighted sections.; I hope this answers your questions. Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam4210OpenMr. Eric E. Gough, Manager, Corporate Technical Affairs, Lucas Industries, Inc., P.O. Box 7002, Troy, MI 48007-7002; Mr. Eric E. Gough Manager Corporate Technical Affairs Lucas Industries Inc. P.O. Box 7002 Troy MI 48007-7002; Dear Mr. Gough: This is in reply to your letter of August 19, 1986, to this Office asking for confirmation of your understanding 'that other light sources can be added to a replaceable bulb headlamp, such as a parking lamp or signal lamp function, as long as the lamps operate independently of each other and are in full compliance with FMVSS 108.'; Your interpretation is essentially correct, and I am enclosing a cop of a recent letter that we sent to Ichikoh Industries on the same subject. In order to be in full compliance with Standard No. 108, if a replaceable bulb headlamp also incorporates a turn signal lamp, the requisite separation distance or candela ratio specified by the standard must be met.; I hope that this answers your question. Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam1012OpenMr. John H. Fildew, Attorney, Fildew, Gilbridge, Miller & Todd, 3156 Penobscot Building, Detroit, MI 48226; Mr. John H. Fildew Attorney Fildew Gilbridge Miller & Todd 3156 Penobscot Building Detroit MI 48226; Dear Mr. Fildew: This is in response to your letter of February 14, 1973, in which yo asked about the responsibilities with respect to the motor vehicle safety standards of an automobile dealer who sends a new vehicle to specialty manufacturer for modifications. You asked whether the dealer must file reports as a final-stage manufacturer, or ascertain whether the specialty manufacturer has filed reports or certified the vehicle.; The final-stage manufacturer in the case you describe is the specialt manufacturer, and all the responsibilities that pertain to that category lie with him, not the dealer. There is also no obligation for the dealer to ascertain that the specialty manufacturer has filed reports.; The answer with respect to the dealer ascertaining that the final stage manufacturer has certified the vehicle is somewhat less clear. There is no direct responsibility for this, a failure of the final-stage manufacturer to certify would not itself bring down any penalties on the dealer. However, the certification is designed to protect the dealer, in cases of nonconformity with the standards of which the dealer does not have actual knowledge. (See sections 108(b)(2) and 114 of the National Traffic and Motor Vehicle Safety Act, 15 U.S.C. 1397(b)(2), 1403.) To put it negatively, if the vehicle were completed in violation of applicable standards and it were not certified, a dealer might be considered to have sold a nonconforming vehicle without the exercise of due care, in violation of the Act. The question is further complicated by the fact that not all alterations would rise to the level of manufacturing (addition of trailer hitches probably would not, for example). and these minor changes would not require additional certification by anyone. In sum, although there is no direct legal obligation for the dealer to see that there is a certification where there are major alternations, it is a very good idea, for his own protection.; The regulations on this subject are codified in Parts 567 and 568 o Title 49, Code of Federal Regulations. The October 1, 1972 edition of that title is current with respect to those parts. We do have a proposal outstanding to make some amendments regarding the certification of altered vehicles (37 FR 22800, October 25, 1972), and an amended rule may be issued in the near future.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam4640OpenMr. Bernie Cantleberry 5958 Maplewood Road Mayfield Heights, Ohio 44l24; Mr. Bernie Cantleberry 5958 Maplewood Road Mayfield Heights Ohio 44l24; "Dear Mr. Cantleberry: This responds to your letter concerning Safet Standard No. l05, Hydraulic Brake Systems. You asked several questions about the standard's requirements for parking brakes. Your questions are addressed below. By way of background information, the National Highway Traffic Safety Administration does not provide approvals of motor vehicles or motor vehicle equipment. Under the National Traffic and Motor Vehicle Safety Act, it is the responsibility of the manufacturer to ensure that its vehicles or equipment comply with applicable standards. The following represents our opinion based on the facts provided in your letter. Your first question concerns section S5.2. That section requires specified vehicles to be 'manufactured with a parking brake system of a friction type with a solely mechanical means to retain engagement . . . .' You asked what is meant by a 'parking brake system of a friction type with a mechanical means.' In understanding section S5.2, I believe it is helpful to focus on three aspects of the language quoted above. First, a vehicle must be 'manufactured with a parking brake system.' The term 'parking brake' is defined in 49 CFR Part 57l.3 as 'a mechanism designed to prevent the movement of a stationary motor vehicle.' Second, the required parking brake system must be 'of a friction type,' i.e., it must prevent the movement of a stationary motor vehicle by means of friction. For example, a parking brake which presses a brake shoe against a brake drum operates by friction, whereas the parking pawl of an automatic transmission does not. Third, the required parking brake system must have a 'solely mechanical means to retain engagement.' Thus, the parking brake cannot be held by non-mechanical means such as fluid, air or electricity. Your second question concerns section S5.2.2. You asked whether it is necessary to meet S5.2.2.l, S5.2.2.2, and S5.2.2.3 (i.e., all three subsections) in order to comply with section S5.2.2, or just one of the subsections. Section S5.2.2 provides that '(a) vehicle of a type described in S5.2.l at the option of the manufacturer may meet the requirements of S5.2.2.l, S5.2.2.2, and S5.2.2.3 instead of the requirements of S5.2.l,' if the vehicle has a transmission or transmission control which incorporates a parking mechanism, and the parking mechanism must be engaged before the ignition key can be removed. (Emphasis added.) Given section S5.2.2's use of the word 'and' (as highlighted above), it is necessary to meet the requirements of all three subsections in order to comply with that section's compliance option. You also asked whether a vehicle which has a parking control in the transmission must also have a hand or foot operated control for the brake system. In responding to this question, I assume that the term 'parking control in the transmission' refers to a parking pawl. As noted above, a vehicle manufactured with a parking pawl alone, without an additional parking brake, would not meet section S5.2's requirement that the vehicle be 'manufactured with a parking brake system of a friction type with a solely mechanical means to retain engagement . . . .' Thus, a vehicle which has a parking control in the transmission must also have an additional parking brake 'of a friction type with a solely mechanical means to retain engagement. . . .' Finally, you asked whether a vehicle with a hydraulic locking system would be sufficient to meet the requirements specified in S5.2.2. This question was asked both for a vehicle that has a parking control in the transmission and for a vehicle with a manual transmission. The requirement that a vehicle be 'manufactured with a parking brake system of a friction type with a solely mechanical means to retain engagement' cannot be met by a hydraulic locking system, since such the parking brakes on such a system are held by fluid pressure rather than by 'a solely mechanical means.' Thus, regardless of whether a vehicle has a parking pawl or has a manual transmission, a hydraulic locking system cannot be used to meet Standard No. l05's parking brake requirements. I hope that this answers your questions. Sincerely, Stephen P. Wood Acting Chief Counsel"; |
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ID: aiam3185OpenMr. Jeffrey Libman, President, Edison Rubber Company, P. O. Box 254, Edison, New Jersey 08817; Mr. Jeffrey Libman President Edison Rubber Company P. O. Box 254 Edison New Jersey 08817; Dear Mr. Libman: This responds to your letter of November 9, 1979, inquiring if it i permissible for your suppliers to cut off the DOT serial numbers on used tires before selling those tires to your company. You stated in your letter that your company buys used tires from several companies. These tires generally either have cuts in the tread or sidewalls or are out of round. Your company then resells the tires to another company, which resells the tires to the public.; The answer to your question is no. The presence of the DO identification number on tires is required by several of this agency's regulation. Our tire identification and record keeping regulation (49 CFR Part 574) requires that each manufacturer place the DOT number on at least one sidewall of each tire that it manufactures. The number serves several purposes. It is indispensable in aiding consumers to identify tires subject to a recall campaign for safety defects and noncompliance with the safety standards. It also aids this agency in enforcing its tire safety standards. Federal Motor Vehicle Safety Standards 109 (Passenger car tries, 49 CFR 571.119) and 119 (Tires for vehicles other than passenger cars, 49 CFR 571.119) require that each tire manufacturer certify that its tires conform to all applicable Federal safety standards by branding or molding the DOT number on the tire.; Section 108(a)(2)(A) of the National Traffic and Motor Vehicle Safet Act of 1966, as amended (15 U.S.C. 1397(a)(2)(A)), states that, 'No manufacturer, distributor, dealer, or motor vehicle repair business shall knowingly render inoperative, in whole or in part, any device or element of design installed on... an item of motor vehicle equipment in compliance with an applicable federal motor vehicle safety standard ....' By removing the DOT identification number from a tire, the person would be knowingly rendering inoperative an element of design on the tires which is included on the tire for compliance with the requirements of a Federal motor vehicle safety standard. Section 109 of the Act (15 U.S.C. 1398) specifies a penalty of up to $1,000 for each violation of section 108.; 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.