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: aiam0327OpenMr. Yoshiyuki Mizuno, Engineering Representative, Nissan Motor Co. Ltd., Liaison Office in U.S.A., 400 County Avenue, Secaucus, NJ 07094; Mr. Yoshiyuki Mizuno Engineering Representative Nissan Motor Co. Ltd. Liaison Office in U.S.A. 400 County Avenue Secaucus NJ 07094; Re: Interpretation of Motor Vehicle *Safety Standard No. 101*#Dear Mr Mizuno:#In your letter of April 27 you ask whether it is permissible to use the words 'emergency throttle' to identify the hand throttle which Standard No. 101 requires to be identified by the word 'throttle' alone.#In our opinion the use of identifying words or symbols in addition to those required or permitted by Standard No. 101 is permissible as long as the additional words or symbols do not conflict with those required or permitted. We see no such conflict in this instance and confirm your belief 'that this wording can be used.'#Sincerely, Lawrence R. Schneider, Acting Chief Counsel; |
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ID: aiam5125OpenMr. James L. Vasko 527 Old Canyon Road Fremont, CA 94536; Mr. James L. Vasko 527 Old Canyon Road Fremont CA 94536; Dear Mr. Vasko: This is in reply to your letter of January 13, 1993, t the agency in which you call our attention to your invention, the 'Front Brake Light System.' You have informed us that your invention utilizes 'the present turn signal lights . . . to notify the driver and or pedestrian in front of the vehicle that the vehicle is in a braking mode,' and that this is accomplished with only the present circuitry. You wish to 'open a dialogue' with us and will answer any questions we may have. We do have some questions about this invention. As you know, the individual front turn signal lamps also operate in tandem as hazard warning signal lamps, and flash simultaneously when the hazard warning switch is activated. We assume that your invention flashes both front signal lamps when the brake pedal is applied, and request confirmation of our assumption. We would also appreciate knowing how this is accomplished without 'necessity and expense of adding new, complicated apparatus' as you put it. If, on the other hand, the front signal lamps are activated in a steady-burning state, that would be of interest to us. Finally, we would appreciate your views as to how this device would enhance safety, as our concerns have been directed to warning those to the rear of the vehicle that it is about to stop, rather than those to the front. When we have this information, we shall be pleased to provide you with an interpretation as to the relationship of your invention to the statutes and regulations that this agency administers. Sincerely, John Womack Acting Chief Counsel; |
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ID: aiam3858OpenMr. M. Iwase, Manager, Technical Administration Department, Koito Mfg. Co., Ltd., Shizuoka Works, 500, Kitawaki, Shimuzu-shi, Shitzuoka-ken, Japan; Mr. M. Iwase Manager Technical Administration Department Koito Mfg. Co. Ltd. Shizuoka Works 500 Kitawaki Shimuzu-shi Shitzuoka-ken Japan; Dear Mr. Iwase: This is in reply to your letter of June 21, 1984, to Mr. Driver of thi agency asking for an interpretation of Motor Vehicle Safety Standard No. 108. Mr. Driver has not been an official of this agency for many years, and in the future, your request for interpretation should be addressed to the Chief Counsel, National Highway Traffic Safety Administration.; Your first question is whether Safety Standard No. 108 permits two-headlamp system on motorcycles. The answer is yes. Paragraph S4.1.1.34 specifies the lighting systems permissible on motorcycles. It allows two Type 2D1 or Type 2 (7 in.), or two Type 2B1 or Type 2B headlamps. Under Table IV, if two headlamps are used, they must be disposed symmetrically around the vertical center line. Two non-sealed headlamps meeting the requirements of SAE J584 may also be used, subject to the same mounting restriction. Therefore the system you propose appears acceptable under Standard No. 108.; You have also asked whether the two headlamps may be mounted one ato the other, rather than side by side. While Table IV specifies that a single headlamp must be mounted 'on the vertical centerline', it requires that two headlamps be disposed symmetrically around it. We do not interpret this language as allowing two headlamps to be mounted adjacent to each other on the vertical centerline.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam1865OpenMr. A.F. Bleiweiss, P.Eng., Vice President, Dominion Auto, Accessories Limited, 420 Keele Street, Toronto 9, Canada; Mr. A.F. Bleiweiss P.Eng. Vice President Dominion Auto Accessories Limited 420 Keele Street Toronto 9 Canada; Dear Mr. Bleiweiss: This is in response to your letter of March 29, 1975, inquiring as t the permissibility of selling your 'Panamirror' in the United States as aftermarket equipment.; Motor Vehicle Safety Standard No. 111, *Rearview Mirrors*, Provide minimum performance requirements for rearview mirrors on passenger cars and multipurpose passenger vehicles. According to the standard, the inside rearview mirror must furnish the driver with a specified field of view to the rear of substantially unit magnification. Any vehicle manufactured for sale, sold, or introduced into interstate commerce must be equipped with an inside rearview mirror that meets the designated level of performance. It appears that the 'Panamirror' would not satisfy the requirements of the provision, because it is convex in structure and therefore would not provide a view of substantially unit magnification.; If the mirror were installed on a vehicle as aftermarket equipmen (after the vehicle's first purchase for purposes other than resale) in such a way as to render inoperative the inside rearview mirror, section 108(a)(2)(A) of the National Traffic and Motor Vehicle Safety Act (Pub. L. 89-563) as amended (Pub. L. 93-492) would apply where the installation was accomplished by a manufacturer, distributer, dealer, or motor vehicle repair business. The section prohibits the named parties from knowingly rendering inoperative a system installed in compliance with an applicable motor vehicle safety standard.; Yours truly, James C. Schultz, Chief Counsel |
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ID: aiam0777OpenMr. J. A. Westphal, Senior Staff Engineer, FWD Corporation, Clintonville, WI, 54929; Mr. J. A. Westphal Senior Staff Engineer FWD Corporation Clintonville WI 54929; Dear Mr. Westphal: This is in reply to your letter of July 7, 1972, concerning th application of Motor Vehicle Safety Standard No. 302, 'Flammability of Interior Materials', as to mattress assemblies.; Paragraph S4.1 of Standard No. 302 lists mattress covers only. Thi does not include the complete mattress assembly.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam5575OpenMr. Yoshiaki Matsui Manager Automotive Equipment Legal & Homologation Section Stanley Electric Co., Ltd. 2-9-13, Nakameguro, Meguro-ku Tokyo 153 Japan; Mr. Yoshiaki Matsui Manager Automotive Equipment Legal & Homologation Section Stanley Electric Co. Ltd. 2-9-13 Nakameguro Meguro-ku Tokyo 153 Japan; Dear Mr. Matsui: This responds to your letter of June 23, 1995, askin questions about neon high mounted stop lamps. The National Highway Traffic Safety Administration answered these questions in the preamble to a notice of proposed rulemaking that was published on June 19, 1995. We assume that you had not received it by the 23rd, and enclose a copy for your information. You will see (center column, page 31940) that Federal Motor Vehicle Safety Standard (FMVSS) No. 108 allows neon tubes as light sources for the center highmounted lamp. Under our interpretation of paragraph S5.1.1.16, FMVSS No. 108 also allows testing of a neon lamp with or without its ballast, in accordance with the directions of that paragraph. If you have any questions, you may refer them to Taylor Vinson of this Office. Sincerely, John Womack Acting Chief Counsel; |
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ID: aiam1536OpenGerahd(sic) P. Riechel, Attorney, Volkswagen of America, Inc., Englewood Cliffs, New Jersey 07632; Gerahd(sic) P. Riechel Attorney Volkswagen of America Inc. Englewood Cliffs New Jersey 07632; Dear Mr. Riechel: This is in reply to your letter of June 18, 1974 informing us tha Volkswagen of America, Inc. has decided not to initiate a notification campaign as a result of a technical violation of Motor Vehicle Safety Standard No. 110. You ask for our concurrence in your decision.; The designated seating capacity of the Dasher vehicle is 5 (2 in front 3 in rear) and you have informed us that 'some early production cars' bore tire inflation pressure labels stating that the capacity was 4 (2 in front, 2 in rear). The other required information (vehicle capacity weight, tire size designation, and recommended inflation pressures) are, you state, correctly indicated.; We agree with you that 'religious observance of the instruction contained on the placard would provide the car with additional load capacity that would go unused', and have concluded that the situation you describe does not indicate the existence of a safety-related defect.; Sincerely, Lawrence R. Schneider, Chief Counsel |
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ID: aiam4734OpenMr. William D. Falcon Commission on Accreditation for Law Enforcement Agencies, Inc. 4242B Chain Bridge Rd. Fairfax, VA 22030; Mr. William D. Falcon Commission on Accreditation for Law Enforcement Agencies Inc. 4242B Chain Bridge Rd. Fairfax VA 22030; "Dear Mr. Falcon: This responds to your letter to our agency concernin your law enforcement standard (71.4.1) for an interior partition you call a 'safety barrier.' I regret the delay in responding. The copy of 71.4.1 you provided states: 'Vehicles used primarily for transporting prisoners (80 percent of their use) should have the driver separated from the prisoner by a safety barrier.' The 'commentary' to 71.4.1 states that, 'The safety barrier may be of wire mesh or heavy gauge plastic to prevent the prisoner from having access to the driver's compartment ...' Mr. Steven Crowell wrote you last year suggesting that this commentary should be revised to state: 'The safety barrier must be one which has had a label or tag affixed to it which certifies compliance with all applicable' Federal motor vehicle safety standards (FMVSS's). Mr. Crowell believes such certification is required by Federal law, and apparently bases this on our September 13, 1985 letter to him. You ask whether his understanding is correct. Mr. Crowell is not entirely correct in his understanding of our certification requirements. Our regulations do not generally require materials in safety barriers to be certified, except for glazing materials in barriers. Standard No. 205, Glazing Materials, applies to all glazing installed in a motor vehicle, including the glazing used for an interior partition. The standard does not require labels or tags to certify the compliance of the glazing material with it. However, the standard does require that glazing material in a barrier must bear a mark to certify compliance with the standard. Standard No. 205 is the only FMVSS that applies directly to interior partitions (and only if the partition contains glazing material). There is no other FMVSS to which the partition itself would be certified. Since glazing material in safety barriers need not be certified by labels or tags, and because safety barriers made from materials other than glazing materials are not certified under Federal law, we believe 71.4.1's seeking to require affixing a certification label or tag on the barriers may engender confusion about NHTSA's requirements. We note also that there is no Federal requirement for persons to certify modifications made to used vehicles. Therefore, we recommend against 71.4.1's seeking to require certifications in the form of labels or tags affixed to safety barriers installed in new or used vehicles. However, we agree with Mr. Crowell that safety barriers should be installed in a safe manner, and believe that our regulations promote this to the extent possible under the Vehicle Safety Act. If a new vehicle is altered by the installation of a partition as original equipment (prior to the vehicle's first sale to a consumer), the person making the installation would be required by 49 CFR Part 567, Certification, to certify (by attaching a label to the vehicle) that the vehicle complies with all applicable FMVSS's. These FMVSS's include the standards for head restraints (Standard 202), interior impact protection (201), rearview mirrors (111), and crash protection (208). We know of no reason why a suitable partition can't be developed which could be placed in a vehicle equipped with head restraints and shoulder belts. Further, it does not seem to be a difficult matter for the barrier to be installed so that the vehicle would meet Standard 111's requirements for rearview mirrors. On the other hand, installation of the barrier could interfere with the compliance of the back of the front seat with Standard 201 (copy enclosed). Paragraph S3.2 of that standard sets energy-absorption requirements for the back of the front seat to protect the heads of rear seat occupants thrown forward in a crash. The partition design should be capable of meeting Standard 201's requirements for energy absorption and should not be hazardous to head impact. If the safety barrier were installed on a used vehicle by a vehicle manufacturer, distributor, dealer or repair business, the installer would be subject to a civil penalty of $1,000 per violation if he knowingly rendered inoperative the compliance of the vehicle with any safety standard. This prohibition is contained in 108(a)(2)(A) of the Vehicle Safety Act. The prohibition of 108(a)(2)(A) does not apply to individual vehicle owners who alter their own vehicles. Thus, under Federal law, they may install or remove any items of motor vehicle equipment regardless of its effect on compliance with Federal motor vehicle safety standards. Manufacturers of motor vehicle equipment, such as the safety barrier you described, also have responsibilities under the Vehicle Safety Act regarding safety defects and noncompliances in their products. Under 151 et seq., they must notify purchasers about safety-related defects and noncompliances and remedy the product free of charge. The Safety Act imposes a civil penalty of $1,000 per violation upon any manufacturer who fails to provide notification of or remedy for a defect or noncompliance in its motor vehicles or motor vehicle equipment. In view of the fact that a police department may alter its own vehicles without regard to 108(a)(2)(A), we believe Mr. Crowell might be suggesting that 71.4.1 recommend that the safety barrier should be installed in a manner that does not negatively affect the compliance of the vehicle with applicable FMVSS's. NHTSA generally encourages vehicle owners not to remove safety equipment or otherwise alter their vehicles if the modification would degrade the safety of the vehicle. Therefore, while we do not agree with Mr. Crowell that you should seek to require affixed certification labels or tags for barriers, we agree that installation of the barrier should be done in a manner that avoids degrading the overall safety of the vehicle. I hope this information is helpful. Please let me know if you have any further questions. Sincerely, Stephen P. Wood Acting Chief Counsel Enclosure"; |
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ID: aiam1166OpenMr. Ray Hartman, Vice President-Engineering, Crown Coach Corporation, 2500 East Twelfth Street, Los Angeles, CA 90021; Mr. Ray Hartman Vice President-Engineering Crown Coach Corporation 2500 East Twelfth Street Los Angeles CA 90021; Dear Mr. Hartman: This is in reply to your letter of June 1, 1973, concerning Standar No. 217, Bus Window Retention and Release.' You raise two questions regarding the standard: the first concerns the incompatibility of the standard with buses designed to transport convicts or other persons under physical restraint, the second, the possibility that the standard may preclude the use of a push-button release mechanism for emergency exits which you apparently presently use in many buses you manufacture.; We have received other communications regarding the incompatibility o Standard No. 217 with buses designed to transport convicts and are presently considering requests that these buses be exempted from the standard.; With respect to the use of push-button emergency exit releas mechanisms, Standard No. 217 does not specify the design of the emergency exit release mechanisms but, rather, specifies requirements which these release mechanisms, regardless of design, are required to meet. These requirements essentially specify the magnitude and direction of release forces necessary to operate the emergency exit release mechanism. If these requirements do preclude the use of a push-button release mechanism you wish to use, the appropriate procedure for you to follow is to petition for rulemaking to amend the standard, in accordance with NHTSA regulations (49 CFR SS553.31 *et seq.*, copy enclosed). We recommend that you include detailed information on the type of release you wish to use as part of any such petition.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam4364OpenLarry F. Wort, Chief, Bureau of Safety Programs, Division of Traffic Safety, Illinois Department of Transportation, 2300 S. Dirksen Parkway, Springfield, IL 62764; Larry F. Wort Chief Bureau of Safety Programs Division of Traffic Safety Illinois Department of Transportation 2300 S. Dirksen Parkway Springfield IL 62764; Dear Mr. Wort: This responds to your May 26, 1987, letter to me asking about ou requirements in Standard 222, *School Bus Passenger Seating and Crash Protection,* for restraining barriers and seat back height. I appreciate this opportunity to explain our requirements. In this discussion, I would also like to go over preemption issues that are raised by the state law you describe.; In your letter, you said that Illinois has recently enacted a la requiring 28-inch-high seat backs on new large school buses (i.e., buses with gross vehicle weight ratings greater than 10,000 pounds). You ask whether the 28-inch-high seat backs would negate the requirement for a restraining barrier in front of the front passenger seat. the answer is no.; Paragraph S5.2 of Standard 222 specifies: 'Each vehicle shall b equipped with a restraining barrier forward of any designated seating position that does not have the rear surface of another school bus passenger seat within 24 inches of its seating reference point . . . .' The standard makes no exception for any type of school bus passenger seat. The reason for the broad application is clear, since restraining barriers are needed to compartmentalize the seating area.; Your second question was whether the height of the restraining barrie must be as high as the height of the extended seat back. The answer is no. The requirements for restraining barrier surface area are found in paragraph S5.2.2 of Standard 222. That section states: 'in a front projected view of the bus, each point of the barrier's perimeter coincides with or lie outside of the perimeter of the seat back of the seat for which it is required.' The seat back of the seat for which a restraining barrier is required has dimensions specified in S5.1.2 of the standard. A restraining barrier must therefore only coincide with or lie outside of the seat back surface required by S5.1.2. If a seat back surface exceeds the size required in Standard 222, the size of the restraining barrier need not coincide. The preemption issue you raise related to the Illinois law mandating the 28-inch-high seat backs and FMVSS 222's seat back height requirement. I have enclosed a copy of our recent letter to Mr. Melvin Smith of your Department which explains that the Illinois law for 28-inch high seat backs is preempted by Federal law. However, as discussed in our letter, the State may require the high seat backs for public school buses.; 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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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.