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: aiam5615OpenMr. Winston Sharples President Cantab Motors, Ltd. RR1, Box 537 Round Hill, VA 22141; Mr. Winston Sharples President Cantab Motors Ltd. RR1 Box 537 Round Hill VA 22141; Dear Mr. Sharples I enclose a copy of an order of the Administrato granting the petition by Cantab Motors for temporary exemption from Motor Vehicle Safety Standards Nos. 208 and 214. The exemption from Standard No. 208 will expire on September 1, 1997, and that for Standard No. 214 on September 1, 1998. In accordance with agency regulations on the subject, within 30 days after your receipt of this letter please provide the Director, Office of Vehicle Safety Compliance, with a copy of the certification label reflecting the exemption that will be used on Cantab's vehicles (49 CFR 555.9(a)). We have received your letter of August 17, 1995, which admits that Cantab manufactured and sold nine vehicles manufactured after the expiration of its previous exemption that did not conform with Standard No. 208, and which enclosed a petition for a determination of inconsequentiality on this matter. This is currently under review. If you have any questions, you may discuss them with Taylor Vinson of this Office (202-366-5263). Sincerely, John Womack Acting Chief Counsel; |
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ID: aiam3907OpenMr. Masaki Ogura, Manager, Truck Engineering, MMC Services Inc., 3000 Town Center, Suite 501, Southfield, MI 48075; Mr. Masaki Ogura Manager Truck Engineering MMC Services Inc. 3000 Town Center Suite 501 Southfield MI 48075; Dear Mr. Ogura: This responds to your letter concerning Federal Motor Vehicle Safet Standard No. 101, *Controls and Displays.* According to your letter, your trucks, which have a GVWR of more than 10,000 pounds, have a coolant temperature sensor for overheat warning and also a coolant level sensor for lack of engine coolant to prevent engine overheating. Both sensors are connected to the same telltale lamp, so that either excessive coolant temperature or lack of coolant will illuminate the telltale. Your letter noted that Standard No. 101 specifies an identifying symbol for coolant temperatures but not a symbol for coolant level. You asked whether a system displaying the symbol specified by Standard No. 101 for coolant temperature meets the requirements of the standard. As discussed below, while some of the Standard No. 101's requirements are applicable to your trucks, the standard's telltale requirements do not apply to truck with a GVWR of 10,000 pounds or more.; Section 5, *Requirements,* states: >>>Each passenger car, multipurpose passenger vehicle, truck and bu manufactured with any control listed in S5.1 or in column 1 of Table 1, and each passenger car, multipurpose passenger vehicles and truck or bus *less than 10,000 pounds GVWR* with any display listed in S5.1 or in column 1 of Table 2, shall meet the requirements of this standard for the location, identification, and illumination of such control or display. (Emphasis added.)<<<; Thus, Standard No. 101's requirements for identification of control are applicable to trucks with a GVWR of 10,000 pounds or more, but the standard's requirements for identification of internal displays are not applicable to such vehicles. Since telltales for coolant temperature are a type of internal display, that requirement of Standard No. 101 is not applicable to the vehicles (more than 10,000 pounds) described by your letter.; Sincerely, Jeffrey R. Miller, Chief Counsel |
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ID: aiam2529OpenMr. Edmund C. Burnett, Paulson and Humphreys, Suite 400, 5272 River Road, Washington DC 20016; Mr. Edmund C. Burnett Paulson and Humphreys Suite 400 5272 River Road Washington DC 20016; Dear Mr. Burnett: This responds to your February 3, 1977, letter asking whether th intersection of a plywood floor panel and the floor channel structure constitutes a 'body panel joint' subject to the requirements of Standard No. 221, *School Bus Body Joint Strength*.; The terms which establish the applicability of the requirements of th standard to a particular section of a school bus body are defined in S4 of the standard. Read together, they establish the following test. If the edge of a surface component (body panel) that encloses the bus' occupant space comes into contact or close proximity with any other body component, the requirements of S5 apply, unless the area in question is designed for ventilation or another functional purpose or is a door, window, or maintenance access panel. Applying this test to the joint your describe, it appears that the joint must comply with the requirements of the standard, because it is the connection of a body component (floor channel structure) with a body panel that encloses occupant space (plywood floor panel).; In youe letter, you argue that the standard is not directed at thes types of joints and that in fact the NHTSA stated that not all joints would be regulated by this standard. While it is true that not all joints are regulated by the standard, all joints between the edge of a body panel and a body component are regulated unless expressly excepted from coverage by the language of the standaard itself. Since the joint you describe connects a body panel to a body component, it is exactly the type of joint for which coverage was intended.; Finally, you argue that all joints located below the floow are no covered by the standard. This is correct. However, the NHTSA has required floor panels regardless of composition to comply with the requirements of the standard, since these panels form the floor and do not fall below it.; Sincerely, Frank A. Berndt, Acting Chief Counsel |
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ID: aiam2528OpenMr. Edmund C. Burnett, Paulson and Humphreys, Suite 400, 5272 River Road, Washington, DC 20016; Mr. Edmund C. Burnett Paulson and Humphreys Suite 400 5272 River Road Washington DC 20016; Dear Mr. Burnett: This responds to your February 3, 1977, letter asking whether th intersection of a plywood floor panel and the floor channel structure constitutes a 'body panel joint' subject to the requirements of Standard No. 221, *School Bus Body Joint Strength*.; The terms which establish the applicability of the requirements of th standard to a particular section of a school bus body are defined in S4 of the standard. Read together, they establish the following test. If the edge of a surface component (body panel) that encloses the bus' occupant space comes into contact or close proximity with any other body component, the requirements of S5 apply, unless the area in question is designed for ventilation or another functional purpose or is a door, window, or maintenance access panel. Applying this test to the joint you describe, it appears that the joint must comply with the requirements of the standard, because it is the connection of a body component (floor channel structure) with a body panel that encloses occupant space (plywood floor panel).; In your letter, you argue that the standard is not directed at thes types of joints and that in fact the NHTSA stated that not all joints would be regulated by this standard. While it is true that not all joints are regulated by the standard, all joints between the edge of a body panel and a body component are regulated unless expressly excepted from coverage by the language of the standard itself. Since the joint you describe connects a body panel to a body component, it is exactly the type of joint for which coverage was intended.; Finally, you argue that all joints located below the floor are no covered by the standard. This is correct. However, the NHTSA has required floor panels regardless of composition to comply with the requirements of the standard, since these panels form the floor and do not fall below it.; Sincerely, Frank A. Berndt, Acting Chief Counsel |
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ID: aiam0092OpenMr. Toyotaro Yamada, Manager, Toyota Motor Company, Ltd., 231 Johnson Avenue, Newark, NJ 07108; Mr. Toyotaro Yamada Manager Toyota Motor Company Ltd. 231 Johnson Avenue Newark NJ 07108; Dear Mr. Yamada: Thank you for your letter of June 27, 1968, in which you requeste clarification of the term 'optically combined' as applied to motor vehicle lights.; 'Optically combined' in this context means that the same lens area i used for more than one function such as tail and stop lights or stop and turn signal lights or tail, stop and turn signal lights. The normal means used to accomplish this 'optically combined' lamp has been to incorporate a single dual-filament bulb with a reflector and lens.; Since the design of your Toyata (sic) Crown combination stop, tail an turn signal lamp is such that a different part of the lens area is used for the turn signal lamp, we do not interpret it to be optically combined with the tail and stop lamp.; The concurrence of the above interpretation with yours and that of th California Highway Patrol should not be construed to be an approval of your design. The results of recent research on lighting and signaling reviewed by this Bureau indicate that signal lights should be separated 4 1/2 to 5 inches minimum (centerline to centerline separation.) Although no dimensions are specified on your drawing it appears to be approximately full scale with a separation distance of 2 1/4 inches between the stop and turn signal lamps. The steady-burning stop lamp may therefore 'wash out' or significantly reduce the effectiveness on the turn signal lamp. Federal Motor Vehicle Safety Standard 108 does not require a minimum separation distance between signal lights, however, upon completion of our present research contracts on rear lighting and signaling, we may consider such a requirement in the future.; Sincerely, David A. Fay, Office of Standards on Accident Avoidance Motor Vehicle Safety Performance Service; |
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ID: aiam2849OpenMr. F. Michael Petler, Assistant Manager, Safety & Legislation Dept., U.S. Suzuki Motor Corporation, 13767 Freeway Drive, Santa Fe Springs, CA 90670; Mr. F. Michael Petler Assistant Manager Safety & Legislation Dept. U.S. Suzuki Motor Corporation 13767 Freeway Drive Santa Fe Springs CA 90670; Dear Mr. Petler: This is in reply to your letter of August 10, 1978, asking for a interpretation of Motor Vehicle Safety Standard No. 108. You have asked 'whether an aftermarket Class A reflex reflector can be installed in addition to the original Equipment Class A reflex reflector, that is, an existing part of the motorcycle's rear combination lamp assembly.' You have stated that 'both reflectors would be installed vertically on the motorcycles vertical centerline,' and have commented that you understand 'that two reflectors may be installed horizontally about the vertical centerline, but it is unclear to us whether they may both be installed one on top of the other, vertically, as this is not addressed in FMVSS No. 108.'; You have misunderstood Standard No. 108. Table IV clearly states wit respect to location of rear reflex reflectors on motorcycles that 'if two are used on the rear, they shall be symmetrically disposed about the vertical centerline.' This requirement precludes the use of two rear reflectors mounted above each other vertically on the vehicle's centerline if your fender extension is sold as an accessory on a motorcycle at the time of its first purchase for purposes other than resale.; Generally, however, Federal standards do not cover vehicles after thei first purchase and an owner may modify his vehicle in any manner he chooses consistent with local law. Modification by dealers, distributors, and repair businesses are prohibited only if they 'render inoperative' any device or element of design installed on a motor vehicle in accordance with a Federal safety standard. Although aftermarket installation of the fender with reflector by a dealer after a vehicle's sale would not be consistent with the reflector location requirements of Standard No. 108, we cannot say that it would 'render inoperative' the reflector installed as original equipment. We therefore have no objection to you offering this component as an aftermarket accessory to be added after a vehicle's initial sale.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam1637OpenMr. Frank L. Wigand Jr., Engineering Department, Todco Division, 2195 Alpine Way, Hayward, CA 94545; Mr. Frank L. Wigand Jr. Engineering Department Todco Division 2195 Alpine Way Hayward CA 94545; Dear Mr. Wigand: This responds to Todco's September 27, 1974, question whether Standar No. 121, *Air brake systems*, 49 CFR 575.121, requires a spring brake system on Todco's 'Jifflox converter dolly.' You describe the Jifflox dolly as a trailer converter dolly which may also be used as a 'third axle attachment' on a two-axle truck.; Standard No. 121 applies to vehicles, and specifies separat requirements for trucks, buses, and trailers. It appears that the Jifflox is subject to separate requirements under the standard depending on its use.; If Todco manufactures and sells the Jifflox for use as a 'traile converter dolly' (defined in 49 CFR 571.3 as a trailer equipped with one or more axles, a lower half of a fifth wheel, and a drawbar), it constitutes a vehicle subject to Standard No. 121. As such it is exempted from the parking brake system requirements (S5.6) and its emergency braking capability is not required to be applied by an emergency source, such as a spring brake, that is not affected by loss of air pressure or brake fluid pressure in the service brake system.; If a truck manufacturer utilizes the Jifflox as an additional axle i the suspension of its vehicle, the truck manufacturer must assure that the truck meets the requirements applicable to it with the Jifflox incorporated in it. This means that, if the truck is manufactured to accept the Jifflox dolly and the truck is rated for a gross vehicle weight rating that depends on inclusion of the axle, the truck must comply with all applicable requirements of the standard with the Jifflox attached. If the truck manufacturer determines that parking brakes are required on the Jifflox axle to meet S5.6.1 or S5.6.2, those parking brakes would have to be applied by an energy source that is not affected by loss of air pressure or brake fluid pressure in the service brake system.; Yours truly, Richard B. Dyson, Acting Chief Counsel |
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ID: aiam3702OpenMr. Roger E. Maugh, Director, Automotive Safety Office, Ford Motor Company, The American Road, Dearborn, MI 48121; Mr. Roger E. Maugh Director Automotive Safety Office Ford Motor Company The American Road Dearborn MI 48121; Dear Mr. Maugh: This responds to your letter of June 2, 1983, regarding Ford's desir to equip 2,500 of its vehicles with Securiflex windshields to obtain field data regarding glass- plastic glazing. You state that such a test fleet would provide Ford with information regarding concerns it has about in-plant handling, vehicle assembly, mirror attachment, haze, scratching, delamination durability, and performance in accidents.; As you are probably aware, General Motors made a similar reques regarding a test fleet of Securiflex windshields last fall. We can give Ford the same assurances that were given to General Motors in response to their request. Under the limited and special circumstances of the field test described in your letter, the agency can firmly state that it would not enforce the abrasion requirement of Safety Standard No. 205 as it now stands since it does not appear to be appropriate for technology like the Securiflex windshield (Securiflex apparently cannot pass the existing abrasion requirements). That technology was developed after the standard was originally issued, and the standard did not contemplate assymetrical (sic) glazing of this type. Equally important, the agency notes that all current information indicates that glass- plastic glazing does have a great potential for reducing lacerative injuries in accidents. The experimental use which you propose should provide valuable information regarding injury reduction and some of the remaining problems which do appear to exist with regard to this type windshield. We also note your statement that the Securiflex windshields you plan to install on the test fleet would comply with the proposed requirements for glass-plastic glazing issued by the agency March 10, 1983 (48 FR 10097).; In light of the agency's policy decision to foster the use of ne safety technology by permitting the field test you propose, the agency expects your company to monitor closely the test fleet and to rectify any problems that may develop. Ford would, of course, remain responsible for meeting its obligation under the Vehicle Safety Act regarding any safety related defects. The agency also expects to be apprised of all information that Ford obtains from this field test.; Sincerely, Diane K. Steed, Acting Administrator |
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ID: aiam2180OpenMr. L. David Minsk, Research Physical Scientist, Department of the Army, U.S. Army Cold Regions, Research and Engineering Laboratory, Hanover, NH, 03755; Mr. L. David Minsk Research Physical Scientist Department of the Army U.S. Army Cold Regions Research and Engineering Laboratory Hanover NH 03755; Dear Mr. Minsk: This responds to your December 11, 1975, request for copies of th Federal laws relevant to the use of trucks as carriers for snowplows and spreader bodies.; The National Highway Traffic Safety Administration (NHTSA) primaril regulates the manufacture of motor vehicles and motor vehicle equipment pursuant to authority of the National Traffic and Motor Vehicle Safety Act of 1966. You requested copies of the Federal laws pertinent to the 'use' of a particular motor vehicle, but standards or laws regulating use are promulgated by the jurisdiction in which a motor vehicle is registered or driven.; It might be noted, however, that motor vehicle safety standards ar applicable to the installation of snowplows and spreader bodies on new trucks. For example, paragraph S4.3.1.1 of Motor Vehicle Safety Standard No. 108, *Lamps, reflective devices, and associated equipment* (49 CFR 571.108), specifies that if motor vehicle equipment, including snowplows, would otherwise prevent compliance with the Standard by any required lamp or reflective device, an auxiliary lamp or reflective device meeting the requirements of the Standard must be provided. Similarily (sic), when a spreader body is installed on a chassicab, the completed trucks must comply with all applicable Federal standards.; The truck dealer or other person who installs motor vehicle equipmen on a truck that is certified as being in compliance with motor vehicle safety standards, prior to first sale of the vehicle, is responsible for ensuring that the truck remains in conformity. Failure to do so would constitute a violation of section 108(a)(1) of the National Traffic and Motor Vehicle Safety Act, and subject the responsible party to the civil penalty provisions and other sanctions of the Act.; When a truck has been sold and is in 'use', the Act prohibits manufacturer, distributor, dealer, or repair business from making alterations that render inoperative any devices or elements of design installed in compliance with the Fderal (sic) safety standards.; Please contact us if we can be of any further assistance. Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam2181OpenMr. L. David Minsk, Research Physical Scientist, Department of the Army, U.S. Army Cold Regions, Research and Engineering Laboratory, Hanover, NH 03755; Mr. L. David Minsk Research Physical Scientist Department of the Army U.S. Army Cold Regions Research and Engineering Laboratory Hanover NH 03755; Dear Mr. Minsk: This responds to your December 11, 1975, request for copies of th Federal laws relevant to the use of trucks as carriers for snowplows and spreader bodies.; The National Highway Traffic Safety Administration (NHTSA) primaril regulates the manufacture of motor vehicles and motor vehicle equipment pursuant to authority of the National Traffic and Motor Vehicle Safety Act of 1966. You requested copies of the Federal laws pertinent to the 'use' of a particular motor vehicle, but standards or laws regulating use are promulgated by the jurisdiction in which a motor vehicle is registered or driven.; It might be noted, however, that motor vehicle safety standards ar applicable to the installation of snowplows and spreader bodies on new trucks. For example, paragraph S4.3.1.1. of Motor Vehicle Safety Standard No. 108, *Lamps, reflective devices, and associated equipment* (49 CFR 571.108), specifies that if motor vehicle equipment, including snowplows, would otherwise prevent compliance with the Standard by any required lamp or reflective device, an auxiliary lamp or reflective device meeting the requirements of the Standard must be provided. Similarily (sic), when a spreader body is installed on a chassicab (sic), the completed trucks must comply with all applicable Federal standards.; The truck dealer or other person who installs motor vehicle equipmen on a truck that is certified as being in compliance with motor vehicle safety standards, prior to first sale of the vehicle, is responsible for ensuring that the truck remains in conformity. Failure to do so would constitute a violation of section 108(a)(1) of the National Traffic and Motor Vehicle Safety Act, and subject the responsible party to the civil penalty provisions and other sanctions of the Act.; When a truck has been sold and is in 'use', the Act prohibits manufacturer, distributor, dealer, or repair business from making alterations that render inoperative any devices or elements of design installed in compliance with the Fderal (sic) safety standards.; Please contact us if we can be of any further assistance. Yours truly, Richard B. Dyson, Assistant 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.