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: aiam2915OpenMr. James Tydings, Thomas Built Buses, Inc., P.O. Box 2450, High Point, NC 27261; Mr. James Tydings Thomas Built Buses Inc. P.O. Box 2450 High Point NC 27261; Dear Mr. Tydings: This responds to your November 7, 1978, question whether the Nationa Highway Traffic Safety Administration's (NHTSA) October 13, 1978, interpretation of the Ninth Circuit air brake ruling has revoked the exclusion of school buses from the 'no lockup' requirements of Standard No. 121, *Air Brake Systems*. You also ask if a bus which is designed identically to a school bus qualifies for the exclusion from 'no lockup' requirements if it is purchased and used for a purpose other than as a school bus.; The answer to the first question is no. The exclusion of school buse from the stopping distance requirements of Standard No. 121 (S5.3.1) remains in effect and was not altered by the October 13, 1978, interpretation.; The answer to the second question is also no. The exclusion fro service brake stopping distance requirements (including the 'no lockup' requirement) is limited to school buses, which are defined at 49 CFR S 571.3 as follows:; >>>'School bus' means a bus that is sold, or introduced in interstat commerce, for purposes that include carrying students to and from school or related events, but does not include a bus designed and sold for operation as a common carrier in urban transportation.<<<; The buses you describe would not qualify as 'sold ... for purposes tha include carrying students to and from school or related events.' Therefore, they would not qualify for the school bus exclusion.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam0928OpenMr. Hilman Meyer, Kettler of America, Inc., 380 Franklin Turnpike, Mahwah, NJ 07430; Mr. Hilman Meyer Kettler of America Inc. 380 Franklin Turnpike Mahwah NJ 07430; Dear Mr. Meyer: A review of correspondence we sent you on October 6, 1972, (in respons to your letter of September 26, 1972, concerning child seating systems you plan to import), has revealed that one statement we made should be clarified.; In the second paragraph of our letter we stated that each 'seat must b labeled or tagged with a certification that it conforms to all applicable Federal motor vehicle safety standards.' Standard No. 213 (49 CFR 571.213), which applies to child seating systems, does require each child seating system to be labeled with information regarding its safe use, and we refer you to the standard for these requirements. However, with respect to certification, manufacturers are not limited to the method specified in our October 6, 1972, letter (viz., attaching a label to the seat), but may certify in other ways as well. For example, Section 114 of the National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1403), on which the certification requirement is based, states that the certification may also be placed on the outside of the container in which the item is delivered.; We regret that our former letter was incomplete in this regard. Sincerely, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam3607OpenMr. Donald J. Cameron, Director - Technical Support, New York City Transit Authority, 25 Jamaica Avenue, Brooklyn, NY 11207; Mr. Donald J. Cameron Director - Technical Support New York City Transit Authority 25 Jamaica Avenue Brooklyn NY 11207; Dear Mr. Cameron: This responds to your recent letter asking whether the driver's sid window and the front entrance door window of a bus may be equipped with plastic glazing. You desire to use plastics because of the high operating cost of replacing broken glass windows.; The answer to your question is no. Safety Standard No. 205, *Glazin Materials*, was amended in 1977 to permit the use of rigid plastic glazing in all doors and windows of buses, *except* windshields or windows to the immediate right or left of the driver (42 FR 61465). The reason for this exception is that windows to the immediate right and left of the driver are necessary for driving visibility and typical plastic material used alone is not sufficiently resistant to abrasion. Plastic glazing would not be allowed in a bus entrance door since this would constitute a window to the immediate right' of the driver. Plastic glazing would be allowed in the rear emergency door, however, if that door was not necessary for driving visibility.; You also ask whether material other than safety glass may be used i either of these locations. I am not sure that I correctly understand your question. If by other materials' you mean, for example, sheet metal, the answer to your question would be yes. There are no Federal requirements specifying that a vehicle have windows in a certain location. Thus, theoretically, there would be nothing to preclude the installation of a solid metal entrance door in a bus. (Obviously, no manufacturer would likely do this because it would compromise driver vision.) If, however, there is a window and it is equipped with traditional glazing materials, the glazing must be in compliance with the performance and location requirements of Standard No. 205. If I have misunderstood your last question, please contact Hugh Oates of my staff and he will clarify the requirements for you (202- 426-2992).; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam5100OpenMr. Robert F. Gayer Equipment Coordinator Transportation Services Salt River Project P.O. Box 52025 Phoenix, AZ 85072-2025; Mr. Robert F. Gayer Equipment Coordinator Transportation Services Salt River Project P.O. Box 52025 Phoenix AZ 85072-2025; "Dear Mr. Gayer: This responds to your letter asking whether certai trailers, manufactured in 1989, were required to comply with Federal Motor Vehicle Safety Standard No. 121, Air Brake Systems. (49 CFR 571.121). You explained that you disagree with statements by the trailers' manufacturer that 'these trailers do not need to comply with `121,' because they are `Heavy Haul Trailers.'' You further stated that the trailers may not comply with certain provisions in Standard No. 121, including the reservoir requirements in S5.2.1.1 and S5.2.1.5. I note that we previously responded to a similar letter from Salt River Project concerning certain trailers manufactured in 1987. Our letter (copy enclosed) was sent to Mr. Derral T. Crance on April 3, 1989. We explained that heavy hauler trailers are not excepted from Standard No. 121 unless they have a GVWR of more than 120,000 pounds. Since you indicated that the trailers of current concern have a GVWR of 68,000 pounds, they would not be excepted from the standard as heavy hauler trailers. Moreover, the trailers do not appear to come within any of the other exceptions to Standard No. 121. Standard No. 121 does, however, include a number of special provisions for heavy hauler trailers, including exceptions from certain requirements. Of particular note, S5.6 sets forth a number of specific parking brake requirements but permits heavy hauler trailers to meet the requirements of either that section, or, at the option of the manufacturer, the requirements of 49 CFR 393.43. Part 393 requires commercial motor vehicles to be equipped with various types of equipment, including brakes. Specifically, section 393.43 addresses brake requirements in breakaway and emergency braking situations. Heavy hauler trailers manufactured in 1989 were generally subject to sections S5.2.1.1 and S5.2.1.5 of Standard No. 121, the provisions about which you specifically asked. Under S5.2.1.1, a reservoir was required to be provided that is capable of releasing the vehicle's parking brakes at least once and that is unaffected by a loss of air pressure in the service brake system. Under S5.2.1.5, each service reservoir was required to be protected against loss of air pressure due to failure or leakage in the system between the service reservoir and its source of air pressure by check valves or equivalent devices. Notwithstanding the general applicability of S5.2.1.1, certain heavy hauler trailers which complied with the requirements of 49 CFR 393.43 instead of the specific parking brake requirements set forth in S5.6 would not have had to comply with S5.2.1.1. This is so because the vehicle is not required to have parking brakes. However, a braking system is required which applies automatically and promptly upon breakaway from a towing vehicle. Such a vehicle would also be required to carry sufficient chocking blocks to prevent movement when parked, as required by 393.41. Since your letter suggests that you purchased trailers that may not have complied with Standard No. 121, I have referred the matter to our Office of Vehicle Safety Compliance for appropriate action. 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: aiam0302OpenTakashi Nakajima, Representative, Mitsubishi Motors Corporation, Detroit Liaison Office, Suite 410 Trowell Building, 24681 Northwestern Highway, Southfield, MI 48075; Takashi Nakajima Representative Mitsubishi Motors Corporation Detroit Liaison Office Suite 410 Trowell Building 24681 Northwestern Highway Southfield MI 48075; Dear Mr. Nakajima: Thank you for your letter of February 17, 1971, to Mr. Douglas W. Toms regarding positioning of the anthropomorphic test devices for use in the crashes described in Federal Motor Vehicle Safety Standard No. 208.; I am enclosing a copy of the newly revised version of the standard a well as an accompanying press release.; In regard to your specific inquiry, Standard No. 208 does not contai specifications for the alignment of the dummy's head once positioned in the vehicle. Paragraphs S3.1.11(b) through (e) specify the procedure for positioning the dummy in the vehicle seat. If the procedures in S8.1.11 are followed as specified, the dummy's neck and head may actually be inclined because of contact with the roof or other vehicle components.; Thank you for your interest in our motor vehicle safety programs. Sincerely, Rodolfo A. Diaz, Acting Associate Administrator, Moto Vehicle Programs; |
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ID: aiam2295OpenMr. Mike Watson, Southside Datsun, 3139 Peach Orchard Road, Augusta, GA 30906; Mr. Mike Watson Southside Datsun 3139 Peach Orchard Road Augusta GA 30906; Dear Mr. Watson: I am writing to confirm your April 29, 1976, telephone conversatio with Mark Schwimmer of this office, concerning the modification work that you perform on Datsun pick- up trucks. I understand that this modification involves removal of the body from a fully certified truck and replacement of the body with a flat bed.; You are a vehicle alterer who is subject to the requirements of 49 CF S 567.7 (copy enclosed). That section requires that you affix a label to the vehicle stating that, *as altered*, the vehicle conforms to all applicable Federal motor vehicle safety standards. If any of the original vehicle's weight ratings are affected by the modification, the modified weight ratings must also appear on this label. As Mr. Schwimmer explained, 'Gross Vehicle Weight Rating' is defined in 49 CFR S 571.3 as:; >>>the value specified by the manufacturer as the loaded weight of single vehicle.<<<; One constraint on this specification is found in S 567.4(g)(3) of 4 CFR Part 567, *Certification*, which requires that the GVWR; >>>shall not be less than the sum of the unloaded vehicle weight, rate cargo load, and 150 pounds times the vehicle's designated seating capacity. . . .<<<; 'Gross Axle Weight Rating' is defined as: >>>the value specified by the vehicle manufacturer as the load carrying capacity of a single axle system, as measured at the tire-ground interfaces.<<<; As one who alters completed vehicles but does not otherwise manufactur motor vehicles or motor vehicle equipment that is subject to a safety standard, you are not required to submit the information specified in 49 CFR Part 566, *Manufacturer Identification*.; Enclosed for your convenience is an information sheet entitled 'Wher to Obtain Federal Motor Vehicle Safety Standards and Regulations.' If you have any further questions, please feel free to write.; Yours truly, Stephen P. Wood, Assistant Chief Counsel |
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ID: aiam5550OpenMr. Donnell W. Morrison 1005 Drinnon Drive Morristown, TN 37814; Mr. Donnell W. Morrison 1005 Drinnon Drive Morristown TN 37814; Dear Mr. Morrison: This is in reply to your letter of April 25, 1995 asking for a clarification of the letter of April 10 to you from the former Chief Counsel, Philip Recht. He explained Standard No. 108's requirements for the location of rear lighting on wide vehicles. As the letter stated, identification lamps are to be mounted 'as close to the top of the vehicle as practicable.' You speak of having seen 'semitrailers on the highway with all the rear lights at bed level' including clearance and identification lamps. As the letter also stated, the determination of practicability is initially that of the manufacturer, to be made in its certification that the vehicle meets all applicable Federal motor vehicle safety standards. NHTSA will not question that determination unless it appears clearly erroneous. Without further information on the semitrailers you saw, we cannot judge whether mounting the clearance and identification lamps at bed level was a clearly erroneous determination by the trailer's manufacturer. There are some configurations where there is no header on which to mount lamps and the top of the doors approaches the top of the vehicle. In those configurations, we would not contest the manufacturer's determination that mounting the lamps at bed level was 'as close to the top of the vehicle as practicable.' On the other hand, the semitrailers you saw might have failed to conform to Standard No. 108. I hope that this clarifies the matter for you. If you have any further questions you may call Taylor Vinson of this Office (202-366-5263). Sincerely, John Womack Acting Chief Counsel; |
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ID: aiam0752OpenMr. Jacinto Navarro, 1701 E. Frierson Avenue, Tampa, Florida 33610; Mr. Jacinto Navarro 1701 E. Frierson Avenue Tampa Florida 33610; Dear Mr. Navarro: I am writing in response to your letter of June 13, 1972, regardin Standard No. 125, Warning Devices. In addition to the final rule (37 F.R. 5038) a copy of which we have already sent to you, a reconsideration and amendment was published in the *Federal Register* on June 22, 1972 (37 F.R. 12323). I enclose a copy of that notice.; You enclose a sketch of a warning device which you have designed, an you ask whether the manufacture of such a device would be permitted under Standard 125. From your drawing the device appears to consist of an 'orange fluorescent colored' balloon to which a triangle of 'reflex-reflective' tape is affixed. The device is inflated and attached to the vehicle roof by a magnet. The device does not have a self-contained energy source, and therefore must meet the shape, size, and performance requirements of Standard 125.; The balloon device as shown in the sketch fails to meet a number of th Standard 125 requirements, including configuration, luminance, (the triangle itself must meet the luminance requirements,) stability, and durability. (See paragraphs S4.2, S4.5, S4.6 and S4.7 of the standard.) accordingly, manufacture of the device as it appears in the drawing would be prohibited by Standard 125.; I hope this answers your questions. Sincerely, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam1840OpenMr. Curtis Eddy, Vice President - Engineering, Matlock Truck Body & Trailer Corp., P. O. Box 7385, Nashville, TN 37210; Mr. Curtis Eddy Vice President - Engineering Matlock Truck Body & Trailer Corp. P. O. Box 7385 Nashville TN 37210; Dear Mr. Eddy: This is to respond to your letter of February 11, 1975, to Mr. Wolfgan Reinhart, concerning your defect notification letter in NHTSA campaign No. 74-0203.; You believe that the second sentence in your notification lette properly determined that the defect existed in Matlock Model trailers. That sentence read, 'Matlock Truck Body and Trailer Corporation has determined that a defect which relates to motor vehicle safety exists in the brake shoes of Standard Forge axles with 12 1/4 and 7 1/2 brake shoes on Matlock Model MTE (electronic trailers).' The NHTSA has consistently viewed a determination stated in this manner as relating to equipment (brake shoes) and not specifically to the vehicle. Matlock's determination should have been that the defect had been determined to exist in the described vehicles. We are aware that the existing requirements (49 CFR S 577.4(b)(1)) are not worded as explicitly as they might be. However, a proposed amendment to Part 577 published November 25, 1974 (39 FR 41182), did attempt to clarify the intent of this section. Should you have need to issue defect notification in the future we would expect the statement of determination to be directed specifically at the vehicles you manufacture.; With respect to your second point, section 577.4(d) calls for th evaluation to mention the possibility of vehicle crash where that is a potential result of the defect. In that regard your notification was clearly deficient.; We hope that this clarifies our earlier letter to you. Please feel fre to write again if you have questions regarding the interpretation or application of any NHTSA requirements.; Yours truly, Andrew G. Detrick, Director, Office of Defect Investigation, Motor Vehicle Programs; |
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ID: aiam4711OpenMr. Michael S. Kmiecik 5601 Western Avenue Omaha, Nebraska 68132; Mr. Michael S. Kmiecik 5601 Western Avenue Omaha Nebraska 68132; "Dear Mr. Kmiecik: This is in reply to your letter with respect t vehicle modification kits you wish to purchase, to be used in conversion of Datsun 240-280Z cars from closed to open vehicles. You have asked for the safety standards that apply to l974-78 convertibles, and whether the conversion kit meets these standards. I regret the delay in responding. We appreciate your efforts to meet the requirements of the National Traffic and Motor Vehicle Safety Act. As you appear to realize, the Act requires, in essence, that vehicle alterations by a motor vehicle manufacturer, distributor, dealer or repair business must not render wholly or partially inoperative any device or element of design installed on that vehicle in accordance with a Federal motor vehicle safety standard. This means that a vehicle at the end of its conversion process must continue to meet the standards that applied at the time that it was first manufactured. This does not preclude conversions that render compliance with a standard physically impossible, obviously an open car cannot meet, for example, the standard for roof crush resistance (Standard No. 216), and convertibles, are, in fact, exempt from it. Such a conversion would allow substitution of a two-point (lap belt) restraint system in a convertible for a three-point (lap-shoulder belt) restraint system that may have been installed when it was a closed car (Standard No. 208). After the vehicle alterations are complete, the vehicle must conform to the barrier tests specified in several standards. We note that the items that comprise the kit are intended to add rigidity to the body and frame after removal of the top, but are unable to advise you of the effect these modifications would have upon the safety performance of the vehicle as converted. There are no Federal safety standards that apply to the individual items in your kit. The standards that apply to motor vehicles, including convertibles, manufactured from October 1, l973, through September 30, l978, will be found at Title 49 Code of Federal Regulations Part 571. Specifically, the standards appear in volumes titled 49 CFR Parts 200 to 999, revised as of October 1, l973, l974, l975, l976, and l977. Originally, these volumes were available through the U.S. Government Printing Office (which may have an Omaha outlet). If they are no longer available through the GPO, we recommend that you consult a local law library. Thank you for your interest in motor vehicle safety. Sincerely, Stephen P. Wood Acting 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.