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: aiam3262OpenMr. Nicholas M. Stefano, Manager, Mechanical Device Development Advanced Systems Engineering, TRW, Inc., Building E2, Room 4062, One Space Park, Redondo Beach, California 90278; Mr. Nicholas M. Stefano Manager Mechanical Device Development Advanced Systems Engineering TRW Inc. Building E2 Room 4062 One Space Park Redondo Beach California 90278; Dear Mr. Stefano: This responds to your letter of January 7, 1980, in which you describ an automotive, electronic display device being designed by TRW and asked for a legal opinion as to its potential compliance with Federal Motor Vehicle Safety Standard No. 127, *Speedometers and Odometers*. You noted that, upon installation in a motor vehicle, TRW's device would continuously display vehicle and engine speed readings in the form of a bargraph. In potentially hazardous situations requiring the driver to take extra caution or to shut down the vehicle's engine, the TRW device would intermittently interrupt the display of vehicle and engine speeds with sequences of verbal messages. In light of this, you asked whether the fact that TRW's device would not display the vehicle speed during every moment of vehicle operation would prevent it from complying with Safety Standard No. 127.; Based on our understanding of your design, it appears that alternatin the display of speed and verbal messages would not violate the standard. Although the future development of electronic digital speedometers was considered in the development of Safety Standard No. 127, the specific type of device described in your letter was not contemplated. The agency had expected that all speedometers would continuously display vehicle speed. While the intermittent display feature would apparently not violate Safety Standard No. 127 as it is now written, we are concerned about the possible adverse impact upon traffic safety that this feature might have. In particular, we have in mind the effects of a driver's(sic) being unable to determine vehicle speed when he or she is approaching or negotiating a curve or exit ramp. Rapid deceleration to a particular speed is typically necessary in such situations.; In the case of a speedometer which periodically does not displa vehicle speed for periods of 5 seconds, a vehicle traveling at 55 mph would cover approximately 400 feet in that interval and a vehicle traveling at 40 mph, approximately 300 feet. Although your alternative mode of operation would reduce this interval through flashing the speed for periods of 0.10 seconds, we question whether such a short period would be sufficient to enable drivers to read their speedometers. We solicit any test or research that TRW has done on the safety side effects of your design. A member of the agency's accident avoidance division will contact you to discuss this issue further.; In looking at your design, we noted several aspects of it that woul apparently not comply with Safety Standard No. 127. The design does not appear to be graduated in both miles and kilometers per hour as required by section 4.1.2. Further, the design neither has the numeral 55 nor highlights either that numeral of the point at which vehicle speed equals 55 mph as required by section 4.1.5.; Finally, I would emphasize that this letter represents only th agency's opinion based on the information supplied in your letter. The NHTSA does not formally render judgement on the compliance of any vehicle or equipment design with any safety standard before the manufacturer's certification of its product. It is the manufacturer's responsibility under the law to determine whether its vehicle or equipment comply with all applicable safety standards and regulations and to certify its vehicles in accordance with that determination.; I hope that your will find this response helpful and have not bee inconvenienced by our delay in sending it to your.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam3798OpenRichard W. Janney, Captain, Commander, A.S.E.D., Maryland State Police, 6601 Ritchie Highway, Glen Burnie, MD 21062; Richard W. Janney Captain Commander A.S.E.D. Maryland State Police 6601 Ritchie Highway Glen Burnie MD 21062; Dear Captain Janney: This is to follow-up your phone conversation with Stephen Oesch, of m staff concerning the agency's letter of December 20, 1983, on Standard No. 205, *Glazing Materials*. I hope that the following discussion will clarify the relationship between the requirements of Standard No. 205 and the render inoperative provision of the National Traffic and Motor Vehicle Safety Act (the Act).; Section 108(a)(2)(A) of the Act prohibits motor vehicle manufacturers distributors, dealers, and motor vehicle repair shops from knowingly rendering inoperative any device or element of design installed in compliance with a Federal motor vehicle safety standard. Standard No. 205 sets performance requirements, including requirements for light transmittance and abrasion resistance, for all glazing materials used in motor vehicles. Those performance requirements may vary depending on the vehicle type involved and the place in the vehicle where the glazing is used. For example, the luminous transmittance and abrasion resistance requirements apply to all windows in a passenger car, but only to windshield and windows to the immediate right and left of the driver in a truck or multipurpose passenger vehicle.; The application of tinting materials to glazing does not, in and o itself, constitute a violation of the render inoperative provision of section 108(a)(2)(A) of the Act. To violate section 108(a)(2)(A), manufacturers, distributors, dealers, and motor vehicle repair shops that install tinting materials must knowingly install materials which render inoperative the glazing material's compliance with Standard No. 205. Thus, for example, a motor vehicle repair shop would be in violation of section 108(a)(2)(A) of the Act if it knowingly installed in a passenger car a tinting material which would render inoperative the glazing's compliance with the abrasion resistance requirements of the standard. In each case, there will be a factual question of whether the glazing material, as tinted, will continue to meet the abrasion resistance requirements of the standard.; If you are aware of any manufacturers, distributors, dealers, or moto vehicle repair shops that are in apparent violation of section 108(a)(2)(A), please provide information concerning those apparent violations to our Office of Vehicle Safety Compliance. The information should be sent to:; >>>Mr. Francis Armstrong, Director Office of Vehicle Safety Compliance National Highway Traffic Safety Administration Room 6113 400 Seventh Street,S.W. Washington, D.C. 20590<<< I hope this discussion will be of assistance to you. If you have an further questions, please let me know.; Sincerely, Frank BErndt, Chief Counsel |
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ID: aiam4773OpenHerr Hanno Westermann Hella KG Hueck & Co Postfach 28 40 4780 Lippstadt W. Germany; Herr Hanno Westermann Hella KG Hueck & Co Postfach 28 40 4780 Lippstadt W. Germany; Dear Herr Westermann: This is in reply to your letter to Dr. Burgett o this agency with respect to 'multi bulb devices', specifically 'how the requirements for one-, two-, or three compartment lamps (lighted sections) as it is documented in FMVSS No. 108, Figure lb have to be interpreted. . . .' You have asked this question because 'Hella would like to equip motor vehicles with signalling devices which have --opposite to conventional lamps--a great number of replaceable miniature bulbs instead of e.g. one 32 cp bulb.' Your question assumes that Standard No. 108 is to be interpreted in a manner that equates the number of lighted sections with the number of bulbs providing the light. Finally, you have stated that the total area of the lamp is not larger than current one-compartment lamps. We regret the delay in responding to your letter, but we have recently completed rulemaking, begun in September l988, which is relevant to your question. On May 15, l990, an amendment to Standard No. 108 was published, effective December 1, l990, the effect of which is to restrict Figure 1b to replacement equipment. I enclose a copy of the amendment for your information. Your question relates to 'signalling devices' for new motor vehicles, and Figure 1b shows that, specifically, you refer to turn signal lamps. Beginning December l, l990, Standard No. 108 will specify two different standards for turn signal lamps. If the lamp is intended for use on multipurpose passenger vehicles, trucks, buses, and trailers whose overall width is 80 inches or more, it must be designed to conform to SAE Standard J1395 APR85 Turn Signal Lamps for Use on Motor Vehicles 2032 mm or More in Overall Width. SAE J1395 also provides that these lamps may be used on vehicles less than this width, except for passenger cars. If a motor vehicle is not equipped with a turn signal lamp designed to conform to SAE J1395, it must be equipped with a turn signal lamp designed to conform to SAE Standard J588 NOV84 Turn Signal Lamps for Use on Motor Vehicles Less Than 2032 mm in Overall Width. In the May l990 amendments, section S3 of Standard No. 108 was amended to add a definition for 'Multiple Compartment Lamp'. Such a lamp is 'a device which gives its indication by two or more separately lighted areas which are joined by one or more common parts, such as a housing or lens.' The multiple bulb device that you described appears to meet this definition. SAE J1395 establishes luminous intensity minima and maxima photometric requirements without reference to either compartments or lighted sections, and all that is required is for the lamp to comply at the individual test points specified. New section S5.1.1.31 clarifies that measurements of a multiple compartment turn signal lamp on vehicles to which SAE J1395 applies are to made for the entire lamp and not for the individual compartments. However, SAE J588 NOV84 continues to specify different minimum photometric requirements for one, two, and three 'lighted sections'. Because the SAE does not prescribe photometric requirements for more than three lighted sections, we have concluded that any device that contains more than three lighted sections need only comply with the requirements prescribed for three lighted sections. I hope that this is responsive to your request. Sincerely, Paul Jackson Rice Chief Counsel; |
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ID: aiam1571OpenMr. John H. Mueller,The Weatherhead Company,300 East 131st Street,Cleveland, Ohio 44108; Mr. John H. Mueller The Weatherhead Company 300 East 131st Street Cleveland Ohio 44108; Dear Mr. Mueller:#This responds to your July 10, 1974, request t modify the hose labeling provisions of Standard No. 106-74, *Brake hoses*, to permit DOT labeling of 1/8-inch O.D. nylon tubing.#To the best of our knowledge 1/8-inch O.D. tubing is not used as brake hose as it is defined by the standard:#>>>'Brake hose' means a flexible conduit manufactured for use in a brake system to transmit or contain the fluid pressure or vacuum used to apply force to a vehicle's brakes'<<<#The tubing is used for pressure gauge lines and in two-speed differentials, but is apparently not used to transmit or contain the pressure used to apply force to a vehicle's brakes. As it is not considered to be brake hose under the standard, it should not be labeled with the DOT symbol.#Aside from this prohibition on the use of the DOT symbol, you are free to label 1/8-inch O.D. nylon tubing as you choose.#Yours truly,Richard B. Dyson,Acting Chief Counsel; |
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ID: aiam4289OpenMr. George Ziolo, 16182 Arena Drive, Ramona, CA 92065; Mr. George Ziolo 16182 Arena Drive Ramona CA 92065; Dear Mr. Ziolo: This letter responds to your inquiry concerning Federal Motor Vehicl Safety Standard No. 111. I apologize for the delay. As I understand your question, you are concerned with a passenger car whose inside rearview mirror apparently does not meet the field-of-view specifications in S5.1 of FMVSS 111 and therefore that must have an outside passenger side mirror in order to comply with the standard. You wish to know whether the need to inscribe the convex mirror in accordance with S5.4.2 is eliminated when the passenger side of the car has both a complying mirror of unit magnification and a convex mirror.; Please understand that the National Highway Traffic Safet Administration (NHTSA) does not approve motor vehicles or motor vehicle equipment. Under the National Traffic and Motor Vehicle Safety Act, it is the manfuacturer's responsibility to ensure that its vehicle or equipment complies with applicable standards. Therefore, this letter is an opinion based on the facts you provide in your letter.; The answer to your question is 'yes.' The passenger side of a new ca would need an outside convex mirror inscribed in accordance with S5.4..2 only if its inside rearview mirror failed to meet the S5.1.1 field of view specifications, and the manufacturer chose to comply with the requirement of S5.3 for an outside passenger side mirror by installing a convex passenger-side mirror. S5.4 provides that the requirements in S5.4.1 - S5.4.3 are applicable to a convex mirror only if that mirror is used to comply with S5.3. In your example, a mirror of unit magnification is used to comply with S5.3. I should add that the manufacturer would have to ensure that installing the convex mirror does not take the mirror of unit magnification out of compliance with FMVSS 111.; Please let me know if you have any further questions. Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam4323OpenMr. Albert Schwarz, Senior Engineer, Product Development, Imperial Clevite Inc., Imperial Eastman Division, 6300 W. Howard Street, Chicago, IL 60648-3492; Mr. Albert Schwarz Senior Engineer Product Development Imperial Clevite Inc. Imperial Eastman Division 6300 W. Howard Street Chicago IL 60648-3492; Dear Mr. Schwarz: This responds to your January 12, 1987 letter to the National Highwa Traffic Safety Administration (NHTSA) concerning Standard No. 106, *Brake Hoses.* You ask whether the standard applies to flexible conduits (i.e., hoses and plastic tubing) used to transmit air pressure to accessories such as horns and Windshield wipers. The answer to your question is yes, if a failure of such a conduit results in a loss of air pressure in the brake system.; On August 3, 1984, NHTSA issued an interpretation of Standard No. 10 to Mr. Terry Teeter of the Eaton Corporation, who asked the same question you did about the applicability of the standard to conduits used for accessories. Our letter explains that flexible hoses (and tubing) connected to accessories are 'brake hoses' and subject to the standard if they transmit or contain the air pressure used to apply force to the vehicle s brakes--i.e., a failure of such a hose would result in a loss of air pressure in the brake system. I have enclosed a copy of our letter to Mr. Teeter for your information.; I understand that Ms. Hom of my staff sent you a copy of a Federa Register notice issued by NHTSA on April 17, 1986, which terminated rulemaking on whether the air brake hose tensile requirement of Standard No. 106 should be reduced for hoses typically used for accessories. NHTSA decided to terminate rulemaking because the agency believed that it would be in the interest of safety for the smaller-diameter hoses to comply with current requirements of the standard. Since you might want to review this notice in light of the information provided you in this letter, I have enclosed a duplicate for your convenience.; You also ask whether there are requirements other than those include in Standard No. 106 that must be met by accessory lines. The answer to your question is no. The air brake hoses you intend to use in accessory lines need comply only with Standard No. 106 to be manufactured and sold in this country.; I hope this information is helpful. Please contact my office if yo have further questions.; Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam1121OpenMr. W. H. Blaine, Manager, Southern California Edison Company, Automotive; Mr. W. H. Blaine Manager Southern California Edison Company Automotive; Dear Mr. Blaine: This is in response to your letter of April 13, 1973, in which you as whether the installation of a truck body or derrick on a new chassis-cab by your company for its own use makes it a final-stage manufacturer subject to the identification and certification provisions implementing the Highway Traffic and Motor Vehicle Safety Act, Public Law 89- 563.; The answer to your question is yes. The completion of a motor vehicl by a manufacturer for its own use does not relieve it of responsibility for certification.; As a final-stage manufacturer, you are required to submit th information specified in 49 CFR Part 566, Manufacturer Identification. I am enclosing a copy of Part 566 for your information. No specific format is required, and a letter report will suffice.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam5162OpenAIR MAIL Mr. T. Kouchi Director Stanley Electric Co., Ltd. 2-9-13, Nakameguro, Meguro-ku Tokyo 153, Japan; AIR MAIL Mr. T. Kouchi Director Stanley Electric Co. Ltd. 2-9-13 Nakameguro Meguro-ku Tokyo 153 Japan; Dear Mr. Kouchi: This responds to your letter of April 2, 1993, to Pau Jackson Rice, the former Chief Counsel of this agency. You refer to Mr. Rice's letter of December 30, 1992, which you interpret as saying that 'any device that contains more than three lighted sections, or LEDs, need only comply with the requirements prescribed for three lighted sections.' You consider 'that the lamps having three lighted sections described in the attached drawing No. 1 & No. 2 need only comply with the photometric requirements prescribed for three lighted sections.' You ask 'if our idea is appropriate.' We confirm your interpretation with respect to drawing No. 1, which appears essentially the same as covered by Mr. Rice's interpretation. With respect to drawing No. 2, this lamp appears to be composed of a panel of LEDs flanked by two incandescent bulbs. When the LED panel alone is operated, or when it is operated in conjunction with either one or both of the incandescent bulbs the requirements applicable to three lighted sections will apply. However, each bulb is regarded as being a single light source so that if the bulbs are operated individually, only the requirements for single lighted sections apply. If the bulbs are operated simultaneously to perform the same function, the requirements for two lighted sections apply. However, if the bulbs are operated simultaneously to perform different functions, the single lighted section requirements apply and all other requirements such as contrast ratios (e.g., the l:5 for tail and stop lamps) must be met. Sincerely, John Womack Acting Chief Counsel; |
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ID: aiam1988OpenMr. W.J. Joyce, Jr.,Consultant, International Business,Grosse Pointe Plaza Bldg.,22725 Mack Avenue,St. Clair Shores, Michigan 48080; Mr. W.J. Joyce Jr. Consultant International Business Grosse Pointe Plaza Bldg. 22725 Mack Avenue St. Clair Shores Michigan 48080; Dear Mr. Joyce:#This responds to your June 18, 1975, question whethe S5.3 of Standard No. 105-75, *Hydraulic Brake Systems*, requires that the brake fluid level warning system specified by S5.3.1 be instantaneous when the brake fluid level reaches the condition described in S5.3.1(b).#The answer to your question if no. The National Highway Traffic Safety Administration recognizes that a minimal interval between the occurrence of the specified condition and the appearance of the required signal is a physical fact. I enclose a copy of an interpretation of a similar require- ment of Standard No. 105-75 for your information. In the case of the brake fluid level indicator, a time interval that is insignificant with respect to the time required to respond to the signal would be permissible.#Sincerely,Frank A. Berndt,Acting Chief Counsel; |
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ID: aiam0360OpenMr. G.K. Pilz, Product Compliance, Mercedes-Benz of North America, Inc., 158 Linwood Plaza, P.O. Box 318, Fort Lee, New Jersey 07024; Mr. G.K. Pilz Product Compliance Mercedes-Benz of North America Inc. 158 Linwood Plaza P.O. Box 318 Fort Lee New Jersey 07024; Dear Mr. Pilz: #This is in reply to your May 21, 1971, letter to Mr E.H. Wallace to determine whether Dunlop is in compliance as to the use of spaces in the tire identification number. #There are no objections to the spaces between the different parts of the number. However, the photograph illustrates another problem, that of a dual size marked tire. Dual size marked tires are not permissible. The tire can be labeled as one size tire with the indication that t replaces another size tire. For example, 20SR14 replaces ER70-14. #The General Secretary of ETRTO has been advised of the 'dual marked' tire usage. #Sincerely, E.T. Driver, Director, Office of Operating Systems, Motor Vehicle Programs; |
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.