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: aiam0219OpenMr. D.J. Broom, Technical Manager (C.V.), The Society of Motor Manufacturers and Traders Limited, Forbes House Halkin Street, London SW1, England; Mr. D.J. Broom Technical Manager (C.V.) The Society of Motor Manufacturers and Traders Limited Forbes House Halkin Street London SW1 England; Dear Mr. Broom: Thank you for your letter of February 2, 1970, to the Federal Highwa Administration, Transmitting the August 1969, edition of the S.M.M.T Tyre and Wheel Engineering Manual.; Your letter also expressed your intention of having the 1969 manua supercede the 1965/66 data book as referenced in Section S3 of Standard No. 109. As we stated in our letter of March 14, 1969, to Mr, Woodbridge, Chief Engineer of S.M.M.T, 'Federal Motor Vehicle Safety Standard No. 109, within Section S3, lists the Tyre and Wheel Engineering Data Book dated 1965/66 of the Society of Motor Manufacturers and Traders Limited (S.M.M.T), 'as one of the references containing acceptable test rims. When Standards No. 109 and 110 were developed, the National Highway Safety Bureau accepted the S.M.M.T. 1965/66 Data Book tire and rim combinations based on established usage. We did not, nor do we at present intend to accept general updating of these referenced publications, either foreign or domestic, as valid reasons for amending Standards No. 109 and 110. Consequently, any new tire size designations or alternative rim sizes that you wish to list within Standards No. 109 and 110 will have to comply, on an individual basis, with the abbreviated guidelines as outline in the October 5, 1968, *Federal Register*.; Sincerely, Rodolfo A. Diaz, Acting Associate Director, Motor Vehicl Programs; |
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ID: aiam0541OpenMr. Howard E. Ballard, Ballard Manufacturing Company, 1063 E. Third Street, Pomona, CA, 91766; Mr. Howard E. Ballard Ballard Manufacturing Company 1063 E. Third Street Pomona CA 91766; Dear Mr. Ballard: This is in reply to your letter of July 17, 1972, concerning th application of Motor Vehicle Safety Standard No. 302, 'Flammability of Interior Materials.' You raise several questions in your letter which are restated below.; >>>1. 'What is the 'grace' period after the law comes into effect. .?'; Standard No. 302 was issued on December 9, 1970, and became effectiv with respect to vehicles manufactured on or after September 1, 1972.; 2. 'Are we correct in assuming that slide-in campers and trave trailers are not affected by this law. . .?'; The Standard applies to passenger cars, multipurpose passenge vehicles, trucks, and buses. It does not apply to trailers (including 'fifth-wheel trailers') or slide-in (including 'cab over') campers.; 3. 'Does the foam in quilted plastic material need to b flame-retardant if the plastic itself (non-quilted) is already flame-proofed?'; 4. 'If the 1/4 inch foam used in quilted material is flame-proofed must a 5 inch core of foam used in a fabricated cushion be flame-proofed, also?'; The Standard provides a detailed description of the components require to meet its requirements, and of the depth of the materials in those components that are required to be tested. Generally, the answer to both of these questions is yes, material within 1/2 inch of the surface of an item is subject to the requirements.; 5. 'On recover jobs, must we replace customer's old foam wit flame-retardant foam?'; Standard No. 302 does not apply to replacement parts of aftermarke materials.; 6. 'Must the plywoods used for backs in dinettes be flame-proofed i the plastic or cloth used to upholster them is already flame-proofed?'; You should note that the Standard does not require 'flame-proofing, rather that the specimens must not burn at more than 4 inches per minute. The test specimens are determined by depth, as stated in our preceding answer, not by the nature of the material. The answer would therefore depend on whether the plywood is within 1/2 inch of the surface.<<<; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam1006OpenMr. Carl Monk, 428 Southland Boulevard, Louisville, Kentucky 40214; Mr. Carl Monk 428 Southland Boulevard Louisville Kentucky 40214; Dear Mr. Monk: Dr. Brinegar asked that I review and respond to your letter of Decembe 23, 1972, regarding warning devices.; As you know from previous correspondence, the National Highway Traffi Safety Administration (NHTSA) issued a Notice of Proposed Rule Making on a standard for warning devices in November 1970. One of our major concerns in issuing this standard was the great variety of warning devices of all sizes, shapes, forms and configurations that were available to the motoring public. While many of these provided varying degrees of effectiveness, the great variety also created confusion and misunderstanding to the motoring public. Standardization of these devices was therefore of prime importance.; In response to this notice many comments, designs and recommendation were suggested for inclusion in the standard. All responses were carefully reviewed and evaluated before we issued the final rule in March 1972. Federal Motor Vehicle Safety Standard No. 125 represents an attempt to achieve a balance between many factors including shapes, size, cost, visibility, stability and weight. Since these triangle are designed for ultimate use in all kinds of vehicles, from passenger cars to heavy trucks, we had to be careful not to specify requirements that would put them beyond the reach of the average motoring public.; We are appreciative of your comments to the docket and your subsequen correspondence of the Department of Transportation, regarding the wind stability requirement of the device. Vehicles traveling at 70 mph do not create an effective wind velocity of 70 mph off the roadside. Research data shows that warning devices designed to withstand wind velocities of approximately 40 mph will be sufficient for the majority of wind conditions created by truck turbulence and atmospheric wind velocities without unnecessary penalties in weight and cost. However, Standard No. 125 will in no way restrict the manufacture and sale of devices with higher wind-resistance capabilities for special uses. These are *minimum* standards.; Again, we appreciate your interest in this aspect of motor vehicle safety. it is the ideas and opinions of concerned individuals, such as yourself, that enable us to ensure rules and regulations that are meaningful and worthwhile to the motoring public. Thank you for writing E.T. Driver, Director, Office of Operating Systems, Motor Vehicle Programs; |
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ID: aiam2172OpenMr. Frank W. Allen, Assistant General Counsel, General Motors Corporation, General Motors Building, Detroit, Michigan 48202; Mr. Frank W. Allen Assistant General Counsel General Motors Corporation General Motors Building Detroit Michigan 48202; Dear Mr. Allen: This is in response to your letter of December 2, 1975, asking thi agency's opinion as to whether Federal Motor Vehicle Safety Standard No. 115, *Vehicle Identification Number*, would preempt any differing State law or regulation specifying the content of a vehicle identification number. You asked the question in the context of a vehicle equipment Safety Commission action recommending such a regulation to the States.; Standard No. 115 requires a vehicle identification that is unique to manufacturer during any ten-year period. It does not specify the length or the content of the number. The question, therefore, becomes whether the Federal safety standard on vehicle identification numbers was intended generally to cover all aspects of those numbers, and preempt any differing State rules, analogously to the situation in which Standard 108 was held to be preemptive in *Motorcycle Industry Council v. Younger*, No. CIV S74-126 (E. D. Cal. 1974). The guiding rule, as set forth by the U.S. Supreme Court in *Florida Lime & Avocado Growers v. Paul, 373 U.S. 132, 141-142 (1963), is 'whether both regulations can be enforced without impairing federal superintendence of the field.' Under the accepted doctrines as set forth in cases such as *Thorpe v. Housing Authority of Durham*, 393 U.S. 268 (1969), and *Chrysler v. Tofany*, 419 F.2d 499, 511-12 (2d Cir. 1969), the interpretation of this question by the administering agency is 'of controlling weight unless it is plainly erroneous or inconsistent with the regulation.'; The NHTSA has determined that the safety standard on vehicl identification numbers, No. 115, is intended to cover all aspects of vehicle identification numbering relative to the vehicles to which it applies, and that any aspects for which there are no specific requirements were intended by this agency to be left to the discretion of the manufacturers. State regulations differing from the Federal standard on this subject are found to 'impair the federal superintendence of the field,' within the meaning of the *Florida Lime* doctrine, and any such State regulation would be preempted under section 103(d), 15 U.S.C. 1392(d).; Sincerely, Frank A. Berndt, Acting Chief Counsel |
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ID: aiam5465OpenSamson Helfgott, Esq. Helfgott & Karas, P.C. 60th Floor Empire State Building New York, NY 10118-6098 Re: Your Ref. No.: 12.065; Samson Helfgott Esq. Helfgott & Karas P.C. 60th Floor Empire State Building New York NY 10118-6098 Re: Your Ref. No.: 12.065; "Dear Mr. Helfgott: We have received your letter to John Womack, th former Acting Chief Counsel of this agency, responding to his letter to you of July 20, 1994. Thank you for enclosing a copy of his letter for ready reference. Our previous letter to you was without the benefit of the diagram of the Caine system which you have now enclosed. The system is intended to be placed 'along the side of trucks and other vehicles.' It consists of three red lamps mounted over three amber (yellow) ones, the array installed between the amber front side marker lamp and the red rear side marker lamp. In normal operation the amber lamps are used as 'running lights' but will be turned off when the red lamps are illuminated in a steady burning state upon application of the brake pedal. The three amber lamps will flash to indicate that the vehicle is turning. All six lamps will flash when the hazard indicator switch is on. If the turn signal is on and the driver's foot is on the brake pedal, the amber lamps will flash while the red ones illuminate in a steady burning state. At 32 candela, the turn signal lamps will be at a higher intensity than the running lamps which operate at 3 to 5 candela. These are within NHTSA specifications. You ask whether this system will be in violation of Standard No. 108. This office has corresponded with you on lighting matters on a number of occasions and you are well aware that supplementary lighting equipment is prohibited as original equipment only if it impairs the effectiveness of lighting equipment that is required by Standard No. 108. This determination is to be made by the manufacturer or dealer who installs the equipment and NHTSA will not question it unless it is clearly erroneous. Sincerely, Philip R. Recht Chief Counsel"; |
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ID: aiam2769OpenMr. Bradford H. Banks, President, Midland Machinery Company, Inc., 101 Cranbrook Ext., Tonawanda, NY 14150; Mr. Bradford H. Banks President Midland Machinery Company Inc. 101 Cranbrook Ext. Tonawanda NY 14150; Dear Mr. Banks: This responds to Midland Machinery Company's February 20, 1978, reques for confirmation that Standard No. 121, *Air Brake Systems*, does not apply to an air braked trailer that carries no cargo and consists entirely of a portable mixing plant.; Section S3 of Standard No. 121 contains an exclusion for any traile whose unloaded vehicle weight is not less than 95 percent of its gross vehicle weight rating (GVWR). 'Unloaded vehicle weight' means the weight of a vehicle with maximun (sic) capacity of all fluids necessary for operation of the vehicle, but without cargo or occupants. You state that the portable mixing plant trailer carries no cargo, and it would thus be excluded from the requirements of Standard No. 121.; Enclosed are copies of Standard No. 108 and 120, along with a information sheet that explains how copies of these and other NHTSA regulations may be obtained.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam2256OpenHonorable Marvin L. Esch, House of Representatives, Washington, DC 20515; Honorable Marvin L. Esch House of Representatives Washington DC 20515; Dear Mr. Esch: The Secretary of Transportation has asked me to respond to your Marc 16, 1976, request for all information submitted to him since December 31, 1975, concerning the safety and economic feasibility of air cushion restraint systems or, in the alternative, the specific basis for withholding particular documents. We interpret your request to include documents submitted to the Office of the Secretary or to the public docket on passive restraints.; All materials concerning the safety and economic feasibility of ai cushion systems that have been placed in the public docket are enclosed. These documents include all material on air cushion systems provided to the Asistant (sic) Secretary for Systems Development and Technology and to the Assistant Secretary for Environment, Safety and Consumer Affairs during their recent visits to General Motors Corporation, Ford Motor Company, and Chrysler Corporation. Films submitted to the docket that support this material are available for viewing at your request.; The NHTSA has provided material to the Office of the Secretary tha discusses the value of requiring passive restraints in motor vehicles. All of this material consists of intro-agency memoranda that contain the opinions of agency staff on the considerations underlying a decision concerning passive restraints. The preparation of this material involved choosing and weighing data and making certain assumptions. I conclude that it is important to have full and free staff input to this decision-making process. Accordingly, I deny your request for this information pursuant to the exemption in the Freedom of Information Act for intra-agency memoranda (5. U.S.C. S 552(b)(5)). I am the person responsible for this decision.; Pursuant to the Regulations of the U.S. Department of Transportatio (49 CFR 7), this decision, to the extent information you seek is not released, may be appealed to John Hart Ely, Esq., General Counsel of the Department, whose decision will be administratively final. Your application for reconsideration must be made in writing within sixty days from the date of receipt of the original denial and must include all information and arguments relied upon in your original request. Such application must indicate that it is an appeal from a denial of a request made under the Freedom of Information Act and the envelope in which the application is sent must be prominently marked with the letters 'FOIA'.; Sincerely, Robert L. Carter, Associate Administrator, Motor Vehicl Programs; |
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ID: aiam0673OpenMr. Philip P. Friedlander, Jr., Director of Communications, National Tire Dealers & Retreaders Association, Inc., 1343 l Street, N.W., Washington, D.C. 20005; Mr. Philip P. Friedlander Jr. Director of Communications National Tire Dealers & Retreaders Association Inc. 1343 l Street N.W. Washington D.C. 20005; Dear Mr. Friedlander: This is in response to your letter of March 28, 1972, asking whethe passenger car tires that have been reclassified, under Standard 109, as 'Unsafe for Highway Use' because they do not conform to the standard may be sold with, or for use on, a vehicle other than a passenger car. For the reasons given below, our answer to your question is no.; Section 108(a)(1) of the National Traffic and Motor Vehicle Safety Ac states that:; >>>'*no person shall* manufacture for sale, *sell*, offer for sale, o introduce or deliver for introduction in interstate commerce, or import into the United States, *any* motor vehicle or *item of motor vehicle equipment* manufactured on or after the date *any applicable Federal motor vehicle safety standard* takes effect under this title *unless it is in conformity* with such standard except as provided in subsection (b) of this section.' (Emphasis supplied.)<<<; We presume that the argument for allowing use of a nonconformin passenger car tire on another type of vehicle (in your case a boat trailer) would be that by so using the tire, it ceases to be a 'tire for use on passenger cars' in the words of the application section of Standard 109, that the standard does not apply to it, and since there is currently no standard for tires on vehicles other than passenger cars, anything may be used on such vehicles.; We would reject this argument. We interpret Standard 109 as applying t tires that are designed and produced for use on passenger cars, and in this view a tire so designed and produced does not become something else because it is ultimately used for a different purpose. the effect of section 108, then, is not merely to prohibit nonconforming passenger car tires from being sold on passenger cars, but to prohibit them from being sold at all, as 'motor vehicle equipment.'; As an entirely separate matter, any reclassified tire sold as moto vehicle equipment would be presumed to contain a safety-related defect within the meaning of sections 111 and 113 of the Act.; Sincerely, Lawrence R. Schneider, Chief Counsel |
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ID: aiam1864OpenMr. D. F. Ryman, Assistant Counsel, Clark Equipment Company, Buchanan, MI 49107; Mr. D. F. Ryman Assistant Counsel Clark Equipment Company Buchanan MI 49107; Dear Mr. Ryman: This is in acknowledgment of your Defect Information Report, i accordance with the defect reporting regulations, Part 573.; The Defect Information Report involves: 57 Brown trailers equipped wit a Kelsey Hayes anti-lock braking system which may malfunction. The following National Highway Traffic Safety Administration identification number has been assigned to the campaign *75-0051*. The first quarterly status report for this campaign is required to be submitted by August 5, 1975. Please refer to the above number in all future correspondence concerning this campaign.; The letter which you have sent to the owners of the subject vehicle does not meet the requirements of Part 577(49 CFR), the Defect Notification regulation. It also does not meet the requirements of the Motor Vehicle and Schoolbus Safety Amendments of 1974. Specifically it does not have the statements required by Part 577.4(a) and (b). The first sentence of your letter should have described the defect as existing in the vehicle itself rather than in the brake control system, since a vehicle manufacturer can only determine the existence of a defect in his vehicles. Properly modified, your first sentence should then be used after the statement required by Part 577.4(a).; Your notification letter also does not inform recipients that they ma inform the Secretary of Transportation if they are unable to have the defect remedied without charge, as required by section 153(a)(6) of the 1974 amendment. The address for this purpose may be given as: Administrator, National Highway Traffic Safety Administration, Washington, D. C. 20590. Also, in response to section 153(a)(5), we believe that an actual date should be given as the earliest date when the defect will be remedied free of charge, since remedy without charge is contingent on actual dates.; It is therefore necessary that you revise the owner notification lette and send a copy to each owner whose vehicle has not yet been corrected. Mailing of the notifications should follow the procedure specified by section 153(c). Please note also that section 153(c)(5) requires that defect notifications (and defect reports) be sent to this office by certified mail.; A copy of Part 577 and the 1974 Amendment is enclosed. If you desir further information, please contact Messrs. W. Reinhart or James Murray of this office at (202) 426-2840.; Sincerely, Andrew G. Detrick, Director, Office of Defect Investigation, Motor Vehicle Programs; |
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ID: aiam4543OpenMr. Davis Thekkanath Sr. Supervising Engineer Oshkosh Truck Corporation P.O. Box 2566 2307 Oregon Street Oshkosh, WI 54903-2566; Mr. Davis Thekkanath Sr. Supervising Engineer Oshkosh Truck Corporation P.O. Box 2566 2307 Oregon Street Oshkosh WI 54903-2566; "Dear Mr. Thekkanath: This responds to your letter requesting a interpretation of Safety Standard No. l2l, Air Brake Systems. Section S5.l.l of the standard requires trucks and buses to have an air compressor of sufficient capacity to bring the pressure in the supply and service reservoirs from 85 psi to l00 psi within a specified time. You inquired about the meaning of this requirement in the context of a truck with a trailer behind it. You particularly asked whether the air compressor capacity requirement includes the volume of service reservoirs for the trailer. As discussed below, only the truck reservoirs need to be considered for this requirement. By way of background information, the National Highway Traffic Safety Administration does not provide approvals for 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 and equipment meet applicable standards. The following represents our opinion based on the facts provided in your letter. Sections S5.l and S5.l.l of Standard No. l2l read as follows: S5.l Required equipment--trucks and buses. Each truck and bus shall have the following equipment: S5.l.l Air Compressor. An air compressor of sufficient capacity to increase air pressure in the supply and service reservoirs from 85 pounds per square inch (p.s.i.) to l00 p.s.i. when the engine is operating at the vehicle manufacturer's maximum recommended r.p.m. within a time, in seconds, determined by the quotient (Actual reservoir capacity x 25)/Required reservoir capacity. The reference in section S5.l.l to 'supply and service reservoirs' refers only to the supply and service reservoirs in the truck or bus subject to the requirement. Similarly, the term 'actual reservoir capacity' refers only to the actual reservoir capacity of that truck or bus, and the term 'required reservoir capacity' refers only to the reservoir capacity required for that truck or bus. Thus, for a truck designed to tow an air-braked trailer, only the truck's reservoirs need to be considered for this requirement. For purposes of testing, the towing vehicle protection system would be activated. While Standard No. l2l does not specify air compressor capacity for towing vehicles in terms which address towed vehicles, we assume that manufacturers of vehicles designed to tow air-braked vehicles will design them to have sufficient air compressor capacity to ensure safe braking performance under conditions of reasonably forseeable use, including when they are towing air-braked vehicles. Sincerely, Erika Z. Jones Chief Counsel"; |
Request an Interpretation
You may email your request to Interpretations.NHTSA@dot.gov or send your request in hard copy to:
The Chief Counsel
National Highway Traffic Safety Administration, W41-326
U.S. Department of Transportation
1200 New Jersey Avenue SE
Washington, DC 20590
If you want to talk to someone at NHTSA about what a request for interpretation should include, call the Office of the Chief Counsel at 202-366-2992.
Please note that NHTSA’s response will be made available in this online database, and that the incoming interpretation request may also be made publicly available.