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: aiam2903OpenMr. William Shapiro, Manager, Regulatory Affairs, Product Planning and Development, Volvo of America Corporation, Rockleigh, NJ 07647; Mr. William Shapiro Manager Regulatory Affairs Product Planning and Development Volvo of America Corporation Rockleigh NJ 07647; Dear Mr. Shapiro:#This is in response to your letter of September 20 1978, requesting an interpretation of Federal Motor Vehicle Safety Standard No. 101-80, *Controls and Displays*.#Specifically, you asked whether the km/h label on Volvo speedometers could appear in upper case letters instead of the lower case letters appearing in Table 2 of the standard. The answer is yes.#Section 5.2.3 of the standard provides that 'any such display for which no symbol is provided in Table 2 shall be identified by the word or abbreviation shown in column 3.' There is no requirement that the identifying words or abbreviations be in the same type face, type size, or case as those printed in the Federal Register. Therefore, as long as the abbreviations are the same as those appearing in Table 2 and are visible, no problem arises because Volvo wishes to use upper case, rather than lower case letters.#Sincerely, Joseph J. Levin, Jr., Chief Counsel; |
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ID: aiam4584OpenMr. Robert H. Munson Director, Automotive Safety Office Environmental and Safety Engineering Staff Ford Motor Company The American Road Dearborn, MI 48121; Mr. Robert H. Munson Director Automotive Safety Office Environmental and Safety Engineering Staff Ford Motor Company The American Road Dearborn MI 48121; "Dear Mr. Munson: This responds to your letter in which you suggeste that there are some apparently inconsistent provisions in Standard Nos. 208, Occupant Crash Protection (49 CFR /571.208) and 209, Seat Belt Assemblies (49 CFR /571.209). With respect to manual belt systems installed at front outboard seating positions in a vehicle which is certified as complying with the dynamic testing requirements in Standard No. 208, you asked whether those belt systems may be equipped with load limiters, such that the belt assembly does not comply with the elongation requirements in Standard No. 209. For the reasons explained below, the answer is no. Your letter suggested that Standard No. 209 contains two different provisions that yield inconsistent answers to this question. On the one hand, section S4.5(b) of Standard No. 209 reads as follows: 'A Type 1 or Type 2 seat belt assembly that includes a load limiter and that does not comply with the elongation requirements of this standard may be installed in motor vehicles only in conjunction with an automatic restraint system as part of a total occupant restraint system.' Section S3 of Standard No. 209 defines a 'load limiter' as 'a seat belt assembly component or feature that controls tension on the seat belt to modulate the forces that are imparted to occupants restrained by the belt assembly during a crash.' These provisions of Standard No. 209 seemingly preclude the use of a load limiter on manual belts, if the load limiter results in the belt assembly not complying with those elongation requirements, unless the seating position in which such manual belts is also equipped with an automatic restraint system. Accordingly, dynamically tested manual belts installed at seating positions that do not include any automatic restraint system could not be equipped with a load limiter, if the load limiter resulted in the belt no longer complying with the elongation requirements. On the other hand, section S4.6 of Standard No. 209 exempts dynamically tested manual belts from the elongation requirements of the standard, as well as the webbing width and strength requirements. This exemption applies without respect to whether the dynamically tested manual belt is equipped with a load limiter. Ford suggests that this provision means that a manual belt installed at a front outboard seating position could be equipped with a load limiter, even if the load limiter resulted in the belt assembly not complying with the elongation requirements, provided that the vehicle in which the belt was installed was certified as complying with the dynamic testing requirements in Standard No. 208. In your letter, you said that it was Ford's interpretation that the requirements of S4.6 of Standard No. 209 were meant to limit the prohibition in S4.5 of Standard No. 209, by permitting the use of load limiters that result in the belt assembly no longer complying with the elongation limits on either automatic belts or dynamically-tested manual belts. You suggested that the reasoning that caused the agency to limit the use of load limiters that result in the belt not complying with the elongation requirements to automatic belts only, in section S4.5, does not apply to dynamically tested manual belts. You quoted the following language from the notice that established S4.5: T here are currently no dynamic performance requirements or injury criteria for manual belt systems used alone. There are no requirements to ensure that a load-limiting belt system would protect vehicle occupants from impacting the steering wheel, instrument panel, and windshield, which would be very likely if the belts elongated beyond the limits specified in Standard No. 209. Therefore, the elongation requirements are necessary to ensure that manual belts used as the sole restraint system will adequately restrain vehicle occupants. 46 FR 2618, at 2619, January 12, 1981. You noted that this reasoning is now outmoded for some manual belts, because dynamic testing requirements have been established for certain manual belts. In fact, you asserted that the agency has expressly recognized this by exempting dynamically-tested manual belts from the elongation requirements of Standard No. 209. Accordingly, you believe that S4.5 of Standard No. 209 should be interpreted to permit the use of load limiters that cause the belt to no longer comply with the elongation requirements on either automatic belts or dynamically tested manual belts. As further support for this position, your letter suggested that the agency's notices establishing dynamic testing requirements for manual belt systems show an intent to treat dynamically-tested manual belts in the same way as automatic belts for the purposes of Standard No. 209. You referred to our rule adopting dynamic testing requirements for manual safety belts in front outboard seating positions of passenger cars (51 FR 9800, March 21, 1986), the rule extending dynamic testing requirements to manual belts installed at front outboard seating positions of light trucks and multipurpose passenger vehicles (52 FR 44898, November 23, 1987), and the denial of petitions for reconsideration asking the agency to rescind the exemption of automatic belts and dynamically tested manual belts from the webbing width, strength, and elongation requirements of Standard No. 209 (53 FR 5579, February 25, 1988). Because of the agency's consistent expression in these three notices of its intent to treat dynamically tested manual belts in the same way automatic belts are treated under Standard No. 209, you believe that the reference in S4.5(b) of Standard No. 209 permitting load limiters on belts used 'in conjunction with an automatic restraint system' should be interpreted to mean load limiters may be installed on belts used in conjunction with an automatic or dynamically tested manual restraint system. I do not concur with your suggested interpretation. I believe that sections S4.5 and S4.6 yield inconsistent answers to your question. Section S4.6(a) exempts manual belts from elongation requirements. However, it does not speak to the consequence of installing a load limiter on a belt that does not comply with those requirements. Section S4.5(b) does speak to this issue. It says that such a belt may be used only in conjunction with an automatic restraint. To be more specific, section S4.5 expressly provides that a belt assembly that 'includes a load limiter and that does not comply with the elongation requirements of this standard may be installed in a motor vehicle only in conjunction with an automatic restraint system as part of a total occupant restraint system.' I appreciate that the discussion you quoted from the 1981 notice is consistent with your argument that load limiters should be permitted on any dynamically-tested manual belt. Nevertheless, regardless of whether you believe that NHTSA intended to make or should have made such a change when in adopting dynamic testing requirements for manual belts, it is not possible to interpret the term 'automatic restraint system,' as used in S4.5, to mean 'automatic restraint system or dynamically tested manual restraint system.' An interpretation cannot add or delete requirements that are not contained in the language of the standard itself. When the agency promulgates a safety standard specifying performance requirements for vehicles or items of equipment to accomplish a particular safety purpose, that safety standard sets forth all the requirements with which the vehicles or equipment must comply. If the requirements in the safety standard do not fully address or ensure the implementation of some aspect of the underlying safety purpose, that aspect is not part of the standard. Since an interpretation cannot amend the language of a safety standard, the agency's only recourse in these situations is to undertake rulemaking to amend the language of the standard. You asked that we treat your request for an interpretation as a petition for rulemaking if, as we have done, we concluded that your suggested interpretation was incorrect. We will notify you of our response to this petition as soon as we complete our review of it. Sincerely, Erika Z. Jones Chief Counsel"; |
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ID: aiam3241OpenMr. Richard C. Stehlik, President, R.C.S. Enterprises, Inc., P.O. Box 925, Waynesboro, VA 22980; Mr. Richard C. Stehlik President R.C.S. Enterprises Inc. P.O. Box 925 Waynesboro VA 22980; Dear Mr. Stehlik: This responds to your letter of February 12, 1979, to Mr. Vladisla Radovich asking whether your 'Kar-Kot' rear seat extension must comply with the Federal motor vehicle safety standard covering child restraints. Your letter was forwarded to my office for reply.; The Federal standard currently in effect for child restraints, Standar No 213, *Child Seating Systems* (49 CFR 571.213), does not apply to 'systems for use only by recumbent or semi-recumbent children.' According to the literature you enclosed with your letter, the Kar-Kot 'has been designed to span the rear floor area and greater part of rear seat' and was 'developed for sleeping/resting'. Since the Kar- Kot is to be used only by recumbent or semi-recumbent children, it is thus exempt from the current standard.; The upgraded version of the child restraint standard, Standard No. 213 *Child Restraint Systems* (44 FR 72131, December 13, 1979), is scheduled to go into effect on June 1, 1980. That standard applies to any device, including devices for use by recumbent or semi-recumbent children, 'designed for use in a motor vehicle to restrain, seat , or position children who weigh not more than 50 pounds.' If the 'Kar-Kot' will only be used by children larger than those intended to be covered by Standard No. 213, *Child Restraint Systems*, your product would not be required to meet the performance requirements of the standard. We note that the literature accompanying your letter makes no mention of any size or age limitations for child (sic) using your product. If the Kar-Kot is not to be used by children under 50 pounds, it should be clearly and permanently labeled to show that it is to be used by a specific size and age range of children.; Regardless of whether it is covered by the standard or not, you product is an item of motor vehicle equipment. Therefore, the recall and remedy provisions of the National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1411-1420) would apply to any safety- related defects in the Kar-Kot.; If you have any further questions, please let me know. Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam1786OpenMr. J.C. Eckhold,Ford Motor Company,Dearborn, Michigan 48121; Mr. J.C. Eckhold Ford Motor Company Dearborn Michigan 48121; Dear Mr. Eckhold:#This responds to your letter of December 19, 1974, t Dr. Gregory, requesting confirmation of your interpretation of Federal Motor Vehicle Safety Standard No. 106-74, *Brake Hoses*.#You described a brake booster system which combines vacuum and hydraulic boost, with the latter supplied by the power steering pump. In a Federal Register notice on June 28, 1974 (39 FR 24012, Docket No. 1-5, Notice 11) the NHTSA exempted certain hydraulic booster hoses from the requirements of Standard No. 106-74. Although no power steering fluid accumulator is used, the hydraulic booster hose which you described is exempt from the requirements of the standard because of the presence of redundant booster power supplied by the independent vacuum booster system.#A future amendment to Standard No. 106-74 to eliminate ambiguity respecting the standard's applicability to hydraulic booster hoses is currently under consideration.#Yours truly,Richard B. Dyson,Acting Chief Counsel; |
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ID: aiam0894OpenMr. Tatsuo Kato, Engineering Representative, Nissan Motor Co., Ltd., 560 Sylvan Avenue, Englewood Cliffs, NJ 07632; Mr. Tatsuo Kato Engineering Representative Nissan Motor Co. Ltd. 560 Sylvan Avenue Englewood Cliffs NJ 07632; Dear Mr. Kato: This is in reply to your letter of August 14, 1972, on the subject o the test dummy specifications of Standard No. 208. I apologize for our delay in replying.; The alignment procedures of S8.1.11 of the standard cause the head t be aligned so that its vertical axis is almost in the same plane as the dummy's back. The necks on most commercial dummies are made of rubber and are installed at such an angle that, as you noted, the specified head alignment cannot be maintained. To correct this misalignment, the necks must be adjusted by shims or other means so that the correct alignment can be maintained.; The center of gravity of the upper thorax is approximated by dimension C and D in Table I and Figure 1 of SAE Recommended Practice J963. The precise location may vary slightly from one dummy model to another due to variances in the distribution of mass in the thoracic area.; Truly yours, Richard Dyson, Assistant Chief Counsel |
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ID: aiam2000OpenMr. Russell O. Lightcap, Chief, Office of Equipment, Department of Transportation, P.O. Box 9067, Sacramento, CA 95816; Mr. Russell O. Lightcap Chief Office of Equipment Department of Transportation P.O. Box 9067 Sacramento CA 95816; Dear Mr. Lightcap: This responds to your letter of June 12, 1975, requesting confirmatio that you as a final-stage manufacturer would only have to check the application and release times of a truck whose chassis you shortened or lengthened in order to certify that vehicle to the requirements of Federal motor vehicle safety standard (FMVSS) No. 121, *Air Brake Systems*.; Certification of vehicles to the standard is an area which ou statutory scheme leaves to the manufacturers, and in which, aside from discussion of general principles, the agency has declined to issue statements of approval.; The National Highway Traffic Safety Administration has stated tha actual road tests by final stage manufacturers are not necessary to establish compliance with Standard No. 121 or other standards, where other reasonable means, such as engineering calculations coupled with laboratory tests, can be used to the same effect. The agency has recognized that small organizations cannot be expected to test to the same scale or by the same methods as the large integrated automotive manufacturers. Supplier warranties and instructions are one of the primary means by which smaller assemblers are expected to use statutory 'due care' to see that their products conform.; From this discussion it should be apparent that verifying only th brake actuation and release functions will probably be an insufficient basis for certifying that the vehicle will comply, for example, with the stopping distance requirements of the standard. Engineering calculations may, however, satisfy you, in the exercise of due care, that the vehicle as modified meets all the requirements of the standard.; The incomplete vehicle documentation provided with the vehicle woul generally serve as the basis of certification to equipment requirements, to the degree that the equipment is undisturbed. The addition of an axle may cause the air reservoirs to no longer satisfy the air volume requirements of the standard.; Sincerely, Frank Berndt, Acting Chief Counsel |
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ID: aiam2450OpenMr. K. W. Schang, Director - Vehicle Safety, Programs, American Motors Corporation, 14250 Plymouth Road, Detroit, MI 48232; Mr. K. W. Schang Director - Vehicle Safety Programs American Motors Corporation 14250 Plymouth Road Detroit MI 48232; Dear Mr. Schang:#This responds to American Motors Corporation's (AMC's September 9, 1976, request for confirmation that Standard No. 101, *Control Location, Identification, and Illumination*, permits the addition of a 'fan' symbol to a control that is identified by the word 'fan' in accordance with the requirements of S4.2.1.#The AMC interpretation is incorrect. Section S4.2.1 states in part:#>>>S4.2.1 . . . . A control may, in addition, be identified by a symbol, but only a symbol shown in column 3 or 4 shall be used. However, if the word 'None' appears in column 3, no symbol shall be provided. . . .<<<#Table I, whose columns are referred to in S4.2.1, contains an entry for 'Heating and Air Conditioning System,' and column 3 for that entry contains the word 'None'. This means that no symbol can be used in addition to the word 'fan' on the control for the fan control switch.#The language in the preambles to three proposals to amend Standard No. 101 that you list in your letter does not have the effect of amending the requirements of the standard itself. As you are no doubt aware, a recent proposal would amend Table I to include a symbol for the heating and air conditioning system, but this proposal has not yet been made final. A copy of the proposal is enclosed for your information.#Sincerely, Frank A. Berndt, Acting Chief Counsel; |
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ID: aiam5395OpenMr. Donald P. Green 809 Huasna Road Arroyo Grande, CA 93420; Mr. Donald P. Green 809 Huasna Road Arroyo Grande CA 93420; Dear Mr. Green: This responds to your letter to this agency askin whether there is a State or Federal regulation prohibiting the use of passenger radial tires on recreational 'pull type' trailers. I regret the delay in responding. You explain that you were told by various tire dealers that radial tires should not be used on trailers because the soft sidewalls of radial tires could cause an uncontrollable swaying that could result in a serious accident. You then state that while towing a trailer mounted with four radial tires, you were caught in a crosswind which caused the trailer to jackknife, resulting in a serious accident. To begin, I am sorry to hear about your accident but am thankful that no one was hurt. The tire safety standards and regulations issued by the National Highway Traffic Safety Administration (NHTSA) require tires to be able to safely carry the load on a vehicle and to be labeled with important safety information, such as tire size, construction, and inflation pressure. There is nothing in our standards or regulations that prohibits the use of passenger car radial tires on trailers. In fact, Federal Motor Vehicle Safety Standard No. 120, 'Tire selection and rims for motor vehicles other than passenger cars,' expressly permits the use of passenger car tires on vehicles like trailers, provided that adjustment is made to the tire's load-carrying capacity. NHTSA also issues consumer advisories to alert consumers to certain practices that should be avoided, such as mixing radial and non-radial tires. However, we have never issued a consumer advisory on the use of passenger car radial tires on trailers, and we are not aware of any widespread hazard due to the use of such tires on trailers. Your State could have requirements for the use of tires on trailers. We suggest that you check with the California Highway Patrol for information on that issue. We regret we are unable to be more helpful. Should you have any further questions, please feel free to contact Walter Myers of my staff at this address or at (202) 366-2992. Sincerely, John Womack Acting Chief Counsel; |
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ID: aiam0197OpenMr. Bernard Belier, U. S. Resident Engineer, U. S. Technical Research Corporation, 801 Second Avenue, New York, NY 10017; Mr. Bernard Belier U. S. Resident Engineer U. S. Technical Research Corporation 801 Second Avenue New York NY 10017; Dear Mr. Belier:#This is in reply to your letter, dated November 11 1969, in which you seek an interpretation as to how Federal Motor Vehicle Safety Standards (FMVSSs) 103 and 104 are applicable to cars equipped with right-hand drive or a central steering wheel.#For motor vehicles equipped with right-hand drive, the windshield areas to be defrosted and wiped by FMVSSs 103 and 104 respectively, are mirror images of those areas required for vehicles equipped with left-hand drive.#More information is required before a reply can be given on vehicles equipped with a central steering wheel. Defrosting and wiping areas requirements would naturally vary depending on the number and location of the front seat passenger seating positions in the vehicle equipped with a central steering wheel.#We trust that we have been of assistance to you.#Sincerely, Robert Brenner, Acting Director; |
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ID: aiam1155OpenMr. J. W. Lane, Manager, Product Promotion, Technical, Publications and Packaging, Mobil Oil Corporation, 150 East 42nd Street, New York, New York 10017; Mr. J. W. Lane Manager Product Promotion Technical Publications and Packaging Mobil Oil Corporation 150 East 42nd Street New York New York 10017; Dear Mr. Lane: This is in reply to your letter of June 1, 1973 and confirms th telephone conversation with Mr. Vinson of my staff on June 14, 1973.; The amendments to Motor Vehicle Safety Standard No. 116 published o May 17, 1973 modified container labeling requirements only for silicone-based brake fluid and hydraulic system mineral oil (paragraph S5.2.2.3) and did not affect the requirements for conventional DOT 3 and DOT 4 fluids (paragraph S5.2.2.2) as your assumed. Therefore you appear to have no problem, and it is not necessary to consider your letter as a petition for reconsideration.; The sample label you enclosed appears to designate the contents a 'Super Heavy Duty Brake Fluid', rather than 'DOT 3 MOTOR VEHICLE BRAKE FLUID' as paragraph S5.2.2.2(e) requires. Otherwise, it is adequate compliance with paragraph S5.2.2.2.; Sincerely, Lawrence R. Schneider, 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.