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: nht76-4.30OpenDATE: 06/03/76 FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA TO: City of Marion TITLE: FMVSS INTERPRETATION TEXT: This responds to your May 6, 1976, request for permission to remove the brake system from two trucks that were manufactured with brake systems conforming to the requirements of Standard No. 121, Air Brake Systems. From the description of the problems you have encountered with the vehicles, I assume that you do not intend to remove the entire brake system, but only one or more antilock systems installed in satisfaction of the "no lockup" requirement of S5.3.1 of Standard No. 121. Section 108(a)(2)(A) of the National Traffic and Motor Vehicle Safety Act (15 U.S.C. @ 1397(a)(2)(A)) prohibits, with one exception, knowing disconnection of the antilock system by a manufacturer, distributor, dealer, or repair business. Your dealer's refusal to remove the devices is probably based on this prohibition. A person that does not fall into these categories is not prohibited from disconnection of the systems. Other State or Federal requirements, such as those of the Bureau of Motor Carrier Safety for operation in interstate commerce, may prohibit disconnection. In any case, the NHTSA urges that you not disconnect safety devices without consulting the vehicle manufacturer with regard to the safety configuration of the vehicle. SINCERELY, CITY OF MARION May 6, 1976 Gordon Lindquist Regional Office National Highway Safety Administration The City of Marion purchased two new Ford trucks in 1975 for use in the Sanitation Department, Serial No's N 80 FVW 47128 and N 80 FVW 47129. These trucks are used for garbage pickup within the city and the brake systems are presenting problems. As I understand this is the Federal Regulation SM2SF-121. I have asked the local Ford dealer, Kennedy Ford, Inc., to remove this system as we can not keep the trucks on the street due to downtime caused by this system. They, of course, refused to do so because of the regulation. The purpose of this letter is a request for permission from you to allow the system to be removed. These trucks have been out of service three times since the purchase and each time is for two to three weeks. I feel this brake system is a safety hazard when used for the purpose stated above. Thank you for your consideration. Charles N. Eblin Service Director |
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ID: nht76-4.33OpenDATE: 05/07/76 FROM: AUTHOR UNAVAILABLE; S. P. Wood; NHTSA TO: Free Enterprise Company TITLE: FMVSS INTERPRETATION TEXT: This responds to your March 12, 1976, request for a listing of Federal motor vehicle safety standards that apply to the manufacturer of a fiberglass hardtop for installation on a Jeep. I am assuming that this top is an aftermarket item and is not incorporated by the Jeep Corporation as the vehicle roof of its product. The only Federal motor vehicle safety standard applicable to this item of aftermarket motor vehicle equipment is Standard No. 205, Glazing Materials, 49 CFR 571.205. Standard No. 205 specifies requirements for glazing materials used in motor vehicles and motor vehicle equipment, including a vehicle top such as you describe. Any glazing material used in the construction of your Jeep top must be certified as being in compliance with Standard No. 205, even though the top itself does not have to be certified. Generally, the prime glazing manufacturer or the glazing fabricator certifies the glazing, so your main concern as manufacturer of the Jeep top is to make certain that you use glazing that has been certified as being in compliance with the standard. If you obtain sheets of glazing from a prime glazing manufacturer and fabricate or mold the glazing yourself, you must mark and certify the glazing as specified in paragraphs S6.4 and S6.5 of Standard No. 205. A copy of the standard is enclosed for your information. Enclosure ATTACH. March 12, 1976 Chief Council -- National Highway Traffic Safety Administration Re: Fiberglass Jeep Top - Safety Requirements Dear Chief Council: Our company is presently preparing to mass produce and market a fiberglass hardtop for Jeep Model CJ-5. The top will include five windows, three of which open, two side doors, and one rear lift-up door. Before we market any tops or commit ourselves irretrievably to a particular form, we need to find out what safety regulations might apply to our product. Therefore, please send us a listing of what requirements for general construction and materials (reinforcement, glass, crash tests, etc.) would apply. In particular, what do the regulations have to say about "suicide" doors (or, doors hinged at the back). Thank you for your assistance. Sincerely, Paula J. Redford (Mrs.) -- Manager, Free Enterprise Company |
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ID: nht76-4.5OpenDATE: 01/07/76 FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA TO: The Leithiser Company TITLE: FMVSS INTERPRETATION TEXT: This responds to your November 14, 1975, question whether an air-braked trailer that carries three spools of electric power line and is designed to pay out and tension the three lines over towers would be required to comply with Standard No. 121, Air Brake Systems. Section S3. (Application) states in part that ". . . the standard does not apply to any trailer whose unloaded vehicle weight is not less than 95 percent of GVWR [gross vehicle weight rating] . . ." It appears from your description that the trailer in question does not have either a passenger-carrying capacity or a rated cargo load. The unloaded vehicle weight would be equal to the GVWR and the trailer would be exculded from the requirements of the air brake standard. YOURS TRULY, The Leithiser Company November 14, 1975 Administrator, Dept. of Transportation National Highway Safety Administration Reference: Standard No. 121, Air Brake Systems, 49 CFR 571.121 Tensioner - Tri-Axle Mounted On March 15, 1974 we submitted a quotation to the Cleveland Electric Illuminating Co., Cleveland, Ohio covering the construction of a piece of special machinery for tensioning electric power lines. On April 10, 1974 we received a purchase order for the equipment. We are enclosing a line sketch of the referenced device. The machine is mounted on a tri-axle suspension because the gross weight of 34,000 lbs. exceeds by 2,000 lbs. the legal limit in Ohio for a tandem axle. Due to recent problems in the delivery of components, this machine will not be completed until March or April of 1976. The addition of "121" equipment to this device, particularly in view of the three axles, would increase the cost to our customer approximately $ 4,000,00. We feel that because this is a specialized piece of equipment that the econimic burden of acquiring certification and the increase in cost to our customer, should relieve us of the necessity for installing the "121" appliances. May we have a ruling in this matter as soon as possible? George L. Leithiser, Pres. (Graphics omitted) The LEITHISER Company York, Fa THREE REEL PAYOFF TRA. DCALO 1/32 "DWO MC. DATE 11/10/75 DWN. WY M. KLINK |
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ID: nht76-5.12OpenDATE: 11/10/76 FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA TO: Anshelewitz, Barr, Ansell & Bonello TITLE: FMVSS INTERPRETATION TEXT: This responds to your September 8, 1976, question whether the windows of "recreational vehicles" qualify as "secondary means of egress" and what Federal requirements would apply to them if they do so qualify. The only Federal requirement for the provision of emergency exists apply to buses (Standard No. 217, Bus Window Retention and Release, 49 CFR 571.217 (copy enclosed)). "Bus" is defined by our regulations to mean "a motor vehicle with motive power, except a trailer, designed for carrying more than 10 persons" (49 CFR 571.3). Thus, Standard No. 217 would apply to the vehicle you describe if it is designed to carry more than 10 persons (including the driver) while the vehicle is in motion. The standard does not use the term "secondary means of egress" but specifies a minimum area of unobstructed opening that may be provided by several means (e.g., emergency door, "push-out window"). SINCERELY, ANSCHELEWITZ BARR ANSEL & BONELLO SEPTEMBER 8, 1976 U.S. Department of Transportation National Highway Traffic Safety Administration Motor Vehicle Program Att: Conrad Cooke Re: Feimster v. Concord Motor Homes Our file #14247 Pursuant to Mr. Williams' telephone conversation with this office on 7 September 1976, he informed me that you have conducted an investigation relative to recreational vehicles having secondary means of egress. Concord Motor Homes, the defendant in the above-captioned matter, alleges that the windows of their recreational vehicle quali as secondary means of egress in that one can break the tempered glass and climb out. The windows involved in this accident were not the "pop-out" type. I do not agree with Concord Motor Homes' assumption that these windows qualify as a secondary means of egress. I would appreciate it if you would forward to me any information you may have with regard to whether or not windows of recreational vehicles qualify as secondary means of egress, and, if so, the standards said windows must comply with as a secondary means of egress. If there is a charge for this information, please advise and I will forward you a check at once. Thank you very much. Richard B. Ansell |
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ID: nht74-4.12OpenDATE: 07/10/74 FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA TO: Flyer Industries Limited TITLE: FMVSS INTERPRETATION TEXT: This responds to your June 5, 1974, question whether electric trackless trolley coaches are motor vehicles under the National Traffic and Motor Vehicle Act of 1966, and if so, whether Standard No. 121, Air brake systems, or any other special requirements must be met by this type of vehicle. Section 102(3) of the Act defines motor vehicle: "Motor vehicle" means any vehicle driven or drawn by mechanical power manufactured primarily for use on the public streets, roads, and highways, except any vehicle operated exclusively on a rail or rails. An electric trackless trolley coach is a motor vehicle under this definition, and Standard No. 121, Air brake systems, applies to a coach equipped with an air brake system. No special requirements apply to trackless trolley coaches. Standard No. 121, Air brake systems, requires stopping distance performance which must be met by any bus equipped with air brakes, whether or not it is equipped with supplementary dynamic braking means. In evaluating a vehicle's compliance with the stopping distance performance requirements of S5.3 and S5.7.2.3, auxiliary braking devices may be utilized in making the stops provided such devices are engaged by means of the same service brake pedal or parking brake control that operates the air brakes. It should be noted, however, that these stops must be made with the transmission selector control in neutral or the clutch disengaged (S6.1.3). FLYER INDUSTRIES LIMITED June 5, 1974 Department of Transportation Att: Office of Legal Information ELECTRIC TRACKLESS TROLLEYS File: 600 E13, E75/50 Dear Sir, We are currently in the negotiation stages for an order to manufacture a number of electric trackless trolley coaches for a number of U.S. transit properties. These vehicles are similar to standard diesel buses in that they are fitted with air brakes, cir suspension, and power steering. Coaches also have electrical braking of the rear wheels. We would be interested to know if HVSS 121, Air Brake Systems Trucks, Buses and Trailers, is applicable to electrically driven vehicles operating from overhead wires. Are there any other special regulations that must be met by this type of vehicle? Yours very truly, A. Deane Director of Engineering |
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ID: nht73-1.32OpenDATE: 07/20/73 FROM: AUTHOR UNAVAILABLE; L. R. Schneider for J. E. Wilson; NHTSA TO: Oregon Traffic Safety Commission TITLE: FMVSS INTERPRETATION TEXT: Thank you for the copy of Oregon House Bill 2721 that you enclosed in your letter of June 25, 1973. We have reviewed it carefully, and have concluded that virtually all of Section 2 is preempted by 15 U.S.C. 1392(d) (copy enclosed). As you may know, this section of the National Traffic and Motor Vehicle Safety Act prohibits a State from having a safety standard applicable to the same aspect of performance as a Federal safety standard unless it is identical to the Federal standard. In this instance, the relevant Federal standard is 49 CFR @ 511.108 Standard No. 108, Lamps, reflective devices, and associated equipment. Section 2 of HB 2721 requires motor vehicles manufactured after October 1, 1975, to be equipped with a green-yellow-red rear mounted lighting system. The NHTSA considers Standard No. 108 to include within its scope all lighting equipment required to be used on the rear of motor vehicles to which it applies. Any State requirements that have the effect of regulating such equipment must therefore be identical to the relevant provision of Standard No. 108. Section 2 of HB 2721 is not identical to the Federal standard relating to that aspect of performance, and must therefore be considered as invalidated as that category of vehicle is expressly excluded from Standard No. 108. Portions of Section 3 (ORS 483.412(3)(a) and (b)) are invalidated for the same reason. The remainder of Section 3 and Section 4 does not conflict with the relevant provisions of Standard No. 108. The guiding principle that we have applied to this situation is that the State requirements that regulate the design of motor vehicles must be identical to the Federal standards. It was clearly the intent of Congress to provide for uniformity of regulation of the manufacturer in areas where the Federal agency has acted, and they did so by the identity requirements of section 1392(d). Sincerely, Enclosures OREGON TRAFFIC SAFETY COMMISSION June 25, 1973 James E. Wilson -- Associate Administrator for Traffic Safety Programs, U.S. Department of Transportation, National Highway Traffic Safety Administration Dear Mr. Wilson: The Oregon Legislature passed H.B. 2721 which allows a green, yellow and red taillight system. A copy is attached for your information. Sincerely, Gil W. Bellamy [Enclosure Omitted.] |
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ID: nht73-1.34OpenDATE: 06/13/73 FROM: AUTHOR UNAVAILABLE; L. R. Schneider; NHTSA TO: The Grote Manufacturing Company TITLE: FMVSS INTERPRETATION TEXT: In your letter of June 4, 1973 you have asked whether a manufacturer may comply with revisions made by the SAE to SAE standards incorporated by reference in Standard No. 108 in the absence of an amendment by NHTSA. The answer is no, and your understanding is correct. A manufacturer must comply with the specific SAE standard and revision set forth in Standard No. 108, regardless of any succeeding revisions made by the SAE. Sincerely, June 4, 1973 U.S. Department of Transportation National Highway Traffic Safety Administration Attention Lawrence R. Schneider -- Chief Counsel Dear Mr. Schneider: The Grote Manufacturing Company is an independent manufacturer of vehicle lighting equipment. In addition to supplying replacement items, we also supply a large number of original equipment vehicle manufacturers. Recently, it has come to our attention that some vehicle manufacturers are under the impression that if an SAE Lighting Standard is referenced in Federal Motor Vehicle Safety Standard 108, they are then permitted to comply to that basic standard, even if the SAE adopts a revision to the standard. For the purpose of citing an example only, MVSS 108 currently requires that turn signal lamps comply with SAE J588d, June, 1966. A later standard, SAE J588e was adopted by the SAE in September of 1970. The specific point in question is whether or not a vehicle manufacturer has the option of complying with the later SAE standard, rather than the one specifically referenced in MVSS 108. A further example could be cited where sidemarker lamps are currently required to comply with SAE J592c. The SAE has again modified this standard and adopted J592d. Specifically, must the manufacturer comply with the referenced DOT standard or does he have the option of adopting the later revision which SAE has issued? It has always been our understanding that the referenced SAE standards apply not only to the basic standards, such as a stop lamp, but rather to the very specific standard including the suffix letter which are cited in MVSS 108. However, we want to be certain we are correct before passing this information on to those customers who have raised this question. Yours very truly, THE GROTE MANUFACTURING COMPANY -- Paul G. Scully, Vice President |
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ID: nht75-5.44OpenDATE: 08/25/75 FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA TO: Harney, Bambic & Moore TITLE: FMVSS INTERPRETATION TEXT: Please forgive the delay in responding to your letter of April 5, 1975, requesting an interpretation of Section 202 of the National Traffic and Motor Vehicle Safety Act of 1966. Section 202 does not directly require any motor vehicle to be equipped with appropriate tires. It instructs this agency to establish, by regulation, motor vehicle safety standards which will in turn require vehicles to be so equipped. Standard No. 110, Tire selection and rims -- passenger cars, implements this instruction with respect to passenger cars. A three-quarter-ton pick-up truck, however, would be subject instead to proposed Standard No. 120, Tire selection and rims for motor vehicles other than passenger cars (copy enclosed). The National Highway Traffic Safety Administration expects to act on that proposal in the near future. Standards issued pursuant to Section 202 do not apply to vehicles after they have been purchased for the purpose of being rented or leased to the general public; they are applicable only to vehicles up to the point of first purchase. SINCERELY, HARNEY, BAMBIC & MOORE ATTORNEYS AT LAW April 5, 1975 Department of Transportation I have a specific question with regard to the applicability of Section 202 of the National Traffic and Motor Vehicle Safety Act of 1966. Does Section 202 apply to three-quarter ton pick-up trucks? If so, does the Act, pursuant to regulations promulgated under the Act, require that a vehicle such as a three-quarter ton pick-up truck be equipped with tires which, according to regulations (perhaps the Tire and Rim Association), are capable of carrying the gross vehicle weight as that gross vehicle weight is identified by the truck manufacturer (such as General Motors Corporation)? My next question is whether or not Section 202 is meant to apply to companies or businesses which engage in the renting or leasing of such types of trucks to the general public. I would very much appreciate any assistance you can give me with regard to the interpretation of Section 202 as outlined above. Thank you very much for your courtesy and cooperation. William S. Hart |
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ID: nht75-2.26OpenDATE: 11/10/75 FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA TO: DPD Mfg. Co., Inc. TITLE: FMVSS INTERPRETATION TEXT: This is in response to your letter of September 22, 1975, requesting information concerning the applicability of Federal motor vehicle safety standards to automatic cruise control devices. As you were advised by telephone, Motor Vehicle Safety Standard No. 124, Accelerator Control Systems, does not preclude the use of cruise control units. While Standard No. 124 requires that the accelerator control device return to "idle" when the operator removes his foot from the accelerator or when the system itself fails, the term "idle position" is defined in S4.1 of the standard to include the position set by a throttle setting device. The rationale for not regulating automatic speed control devices is found in the preamble to the standard, issued on April 8, 1972 (37 FR 7097), which states: The rule does not contain requirements for automatic speed control devices. It was found that although nine recall campaigns involving 61,176 vehicles have concerned these devices, no relationship to accelerator overspeed accidents could be established from automatic speed controls. Of the 540 multi-disciplinary accident reports that were studied in formulating the final rule, none mentioned the automatic system. There are no other Federal motor vehicle safety standards which are concerned with the use of automatic cruise control devices. I trust this information will be useful to you. I have enclosed a copy of Standard No. 124 for your future reference. YOURS TRULY, September 22, 1975 U.S. Department of Transportation Federal Highway Administration National Highway Safety Bureau Enclosed is a copy of our request to you for automatic cruise control safety standards. Your telcon to us revealed that there were no safety standards applicable to cruise control. However, we need this information, in writing, to provide to our customers s required. Thank you for an early reply. DPD MFG. CO., INC. O. D. Hunter Director of Training and Publications May 21, 1975 U.S. Department of Transporation Federal Highway Administration National Highway Safety Bureau We are embarked on a project to manufacture automobile, automatic cruise control devices. Accordingly, please forward appropriate safety standards for our guidance. Thank you for an early reply. DPD MFG. CO., INC. O. D. Hunter Director of Training and Publications |
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ID: nht75-2.48OpenDATE: 07/17/75 FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA Z. VINSON FOR RICHARD B. DYSON -- NHTSA TO: D. R. Bernard, Esq. TITLE: FMVSS INTERPRETATION TEXT: This is in reply to your letter of May 28, 1975, providing further information for our determination whether certain "safety lights" would violate the National Traffic and Motor Vehicle Safety Act of 1966. There is no Federal prohibition against sale of this accessory in the aftermarket. It would, however, be subject to regulation by the states. For the following reasons, it could not be used as original equipment. Standard No. 108 requires a minimum spacing of 4 inches (edge to edge) between the stop lamps and the rear turn signal lamps and a minimum spacing of 9 inches (centerline to centerline) between the turn signals. The purpose of this spacing is to provide a distinctive indication of the turning direction. A flashing stop lamp located in close proximity to the steady-burning stop lamp required by Standard No. 108 would, in our opinion, impair the effectiveness of the rear turn signal within the meaning of S4.1.3, during a combined braking and turning operation. Such a lamp would also be prohibited by S4.6(b) which, in effect, requires all original equipment stop lamps to be steady burning. Yours truly, ATTACH. BERNARD & BERNARD -- ATTORNEYS AT LAW May 28, 1975 Richard B. Dyson -- Assistant Chief Counsel, U.S. Department of Transportation, National Highway Traffic Safety Administration Re: N40-30 (ZTV) Dear Mr. Dyson: Pursuant to your letter, we are providing the following supplemental information in order for you to reach a decision in regard to the proposed safety lights. 1. The flashing lights will be no brighter than the standard brake light, but will be mounted in close proximity to the said brake lights. 2. The flashing lights will be a different color from the turn signals and will not interfere with the operation nor be confused with the turn signals. 3. The flashing lights will be the same color normally as the brake lights and will have a frequency of flashes approximately twice the speed of the signal light for turns. It is hoped that this information will be satisfactory to you, and your conclusion as soon as possible would be appreciated. Yours truly, D. R. Bernard |
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.