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: aiam1540OpenMr. John W. Kourik, Wagner Division, Wagner Electric Corporation, 11444 Lackland Road, St. Louis, MO 63141; Mr. John W. Kourik Wagner Division Wagner Electric Corporation 11444 Lackland Road St. Louis MO 63141; Dear Mr. Kourik: This responds to your March 12, 1974, request for interpretation of th volume requirements for service brake chambers in S5.1.2.1 and S5.2.1.2 of Standard No. 121, *Air Brake Systems*:; >>>S5.1.2 Total service reservoir volume shall be at least eight time the combined volume of all service brake chambers at maximum travel of the pistons or diaphragms.<<<; You also requested the addition of language equating brake chambe volume with brake chamber displacement, based on nominal effective area and rated stroke. In testing for compliance with S5.1.2.1 and S5.2.1.2, the NHTSA will accept a manufacturer's published 'rated volume' of the brake chamber with the piston or diaphragm at maximum travel. This means that the manufacturer may specify the full stroke of the piston or diaphragm and compute the 'rated volume' based on the designed volume of the chamber and the full stroke he has established. This volume may be somewhat larger than 'nominal brake chamber displacement' which does not necessarily account for the void ahead of the relaxed diaphragm or piston, the so-called 'pre-fill volume'. This volume must be included because it must be pressurized along with the displaced volume.; In the absence of manufacturer's published ratings, the NHTSA wil measure the brake chamber volume with the push rod at maximum stroke.; Your request to add explanatory language to the standard of th measurement technique is denied as unnecessary in view of this interpretation.; Sincerely, Robert L. Carter, Associate Administrator, Motor Vehicl Programs; |
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ID: aiam5503OpenMr. Harry C. Gough, P.E. State of Connecticut Department of Motor Vehicles 60 State Street Wethersfield, CT 06161; Mr. Harry C. Gough P.E. State of Connecticut Department of Motor Vehicles 60 State Street Wethersfield CT 06161; "Dear Mr. Gough: This responds to your letter to this office askin whether the retroreflective tape required to outline school bus emergency exits can, in the case of the rear emergency door, be placed on the door itself. The short answer is no. You stated that the State of Connecticut requires that school bus bumpers be black. You further stated that one school bus manufacturer supplied buses with the bottom piece of the retroreflective tape installed on the rear bumper. You then noticed that a number of school buses from a different manufacturer had the bottom part of the tape installed on the door itself. You asked whether the language of S5.5.3 of Federal Motor Vehicle Safety Standard (FMVSS) No. 217, Bus emergency exits and window retention and release, permitted the installation of the retroreflective tape on the door itself. Paragraph S5.5.3 of FMVSS No. 217 (49 CFR 571.217) provides: Each opening for a required emergency exit shall be outlined around its outside perimeter with a minimum 3 centimeters wide retroreflective tape, either red, white, or yellow in color, . . . This requirement was imposed by amendment to FMVSS No. 217 promulgated by a final rule published in the Federal Register on November 2, 1992 (57 FR 49413). In discussing this requirement in the preamble portion of the final rule, we said at 57 FR 49421: Accordingly, the final rule requires a minimum 1 inch wide strip of retroreflective tape, either red, white, or yellow in color, to be placed around the outside perimeter of the emergency exit opening, not the emergency exit itself (emphasis added). As you may know, the buses with the tape on the emergency exit doors have been recalled by the manufacturer. For information about the recall, you can contact the bus manufacturer, Thomas Built Buses, P. O. Box 2450, High Point, NC 27261. Enclosed for your information are two interpretative letters issued by this office on related issues pertaining to the retroreflective tape requirement. See letter to Mr. Thomas D. Turner, Manager, Engineering Services, Blue Bird Body Company, dated July 7, 1993, and letter to Mr. Turner dated March 28, 1994. I hope the above information is helpful to you. Should you have any further questions or need additional information, please feel free to contact Walter Myers of my staff at this address or at (202) 366-2992. Sincerely, Philip R. Recht Chief Counsel Enclosures"; |
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ID: aiam1813OpenMr. Tatsuo Kato, Staff, Safety, Nissan Motor Co., Ltd., P.O. Box 1606, Englewood Cliffs, N.J. 07632; Mr. Tatsuo Kato Staff Safety Nissan Motor Co. Ltd. P.O. Box 1606 Englewood Cliffs N.J. 07632; Dear Mr. Kato: #This is in reply to your letter of January 21, 1975 requesting an opinion on whether either Federal Standard No. 109 or No. 119, or both, apply if Nissan equips a truck with a passenger car tire size (6.95 x 14-4PR). #Standards Nos. 109 and 119 apply to the tire only. consequently, the manufacturer of the tire has presumably made determination as to which standard applied when he manufactured the tire. There is no prohibition in the Federal safety standards to the use of a 'passenger car tire' on a truck. The truck manufacturer should, of course, ensure that the tire has a sufficient load carrying capacity for safe use on a truck. #Yours truly, #Richard B. Dyson, Assistant Chief Counsel; |
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ID: aiam0701OpenNorman W. Quinn, Esq., Messrs,(sic) Nickell, Quinn & Mah, 2131 Seattle First National Bank Building, 1001 Fourth Avenue, Seattle, WA 98154; Norman W. Quinn Esq. Messrs (sic) Nickell Quinn & Mah 2131 Seattle First National Bank Building 1001 Fourth Avenue Seattle WA 98154; Dear Mr. Quinn: This is in reply to your letter of May 5 on behalf of your client Le Ross. Mr. Ross has developed a motor vehicle deceleration warning system that, as described by you, activates two amber lights on the rear of a vehicle. Your letter indicate that these lamps would be incorporated into a vehicle back-up lamp system and that Mr. Ross envisions his system as an aftermarket accessory item rather than as new vehicle original equipment. You state your understanding that Motor Vehicle Safety Standard No. 108 would not preclude marketing the system as an aftermarket accessory, and that back-up lamps are required to be white in color. You ask our advice whether Standard No. 108 prohibits amber lamps in the back-up lighting system and, if so, whether a proposal for amendment of the Standard to allow the system would be feasible.; Standard No. 108 would in certain instances preclude the aftermarke sale of an amber deceleration warning system incorporated into a back-up lamp system. Standard No. 108 as of January 1, 1972, does cover certain aftermarket equipment items, and in some instances would preclude the sale of a back-up light system with amber lamps. Lighting equipment manufactured on or after that date as replacement for similar equipment on vehicles manufactured on or after January 1, 1972, must meet Standard No. 108 which, as you have noted, requires that the color of the back-up lamps be white. Federal law would not preclude sale of this system for use on motor vehicles manufactured before January 1, 1972, or purchase of an amber system by the owner of a vehicle manufactured after that date if he wished to change over from a white to amber system. As a practical matter, however, I believe That(sic) virtually every State has a requirement that back-up lamps be white, and that a back-up light with amber bulbs or lenses would be forbidden. Standard No. 108 would not preclude sale of the Ross System as a separate lighting device. I do not know what position the States would take on such a matter.; Our research contracts on deceleration warning system indicate tha further development and testing under field conditions is necessary before specific proposals can be made by NHTSA. Therefore, I do not think action on a proposal by Mr. Ross would be feasible at this time, though we would welcome his comments to our Docket 69-19 as a comment to be considered in future rulemaking on this subject.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam3984OpenCorporal Frank Browne, Supervisor - Property Services, Santa Ana Police Department, 24 Civic Center Plaza, Santa Ana, CA 92702; Corporal Frank Browne Supervisor - Property Services Santa Ana Police Department 24 Civic Center Plaza Santa Ana CA 92702; Dear Corporal Browne: Thank you for your letter of July 5, 1985, concerning Federa regulations on safety belts in your patrol vehicles. You specifically asked about regulations affecting either the removal of the shoulder belt portion of a lap-shoulder belt system or the replacement of lap-shoulder belt systems with lap belt only systems. I hope that the following discussion answers your questions.; The National Traffic and Motor Vehicle Safety Act authorizes our agenc to establish Federal Motor Vehicle Safety Standards applicable to all new motor vehicles sold in the United states. We have issued Standard No. 208, *Occupant Crash Protection*, which requires the installation of crash protection systems, such as safety belts, in the front and rear seats of motor vehicles. We have also issued Standard No. 209, *Seat Belt Assemblies*, which sets performance requirements for safety belts used in motor vehicles. A copy of each standard is enclosed for your reference. As you know, each new motor vehicle sold to your Department must be certified by its manufacturer as complying with all applicable Federal Motor Vehicle Safety Standards, including Standards Nos. 208 and 209.; The alteration of a safety belt system in a used vehicle is affected b section 108(a)(2)(A) of the Vehicle Safety Act. A copy of that section of the Act is enclosed. That section provides, in part, that:; >>>No manufacturer, distributor, dealer or motor vehicle repai business shall knowingly render inoperative, in whole or part, any device or element of design installed on or in a motor vehicle or item of motor vehicle equipment in compliance with an applicable Federal motor vehicle safety standard....<<<; Thus, none of those commercial businesses could alter or replace th safety belts in your vehicles, if by doing so they would 'render inoperative' the compliance of the vehicle or the safety belt system with Standard Nos. 208 and 209. Removal of a portion of a belt system or the substitution of a lap belt for a lap-shoulder belt would have that effect. Note that Section 108(a)(2)(A) does not apply to individual vehicle owners. Therefore, your Department can remove or alter your safety belts in any manner without violating Federal Law. Such removals or alterations could be affected by State law.; I urge you to carefully consider the effects of altering or removin safety belts, even though Federal law would not prohibit you from making such modifications yourself. Our accident and test data show that lap-shoulder belts are very effective in reducing deaths and injuries in vehicle crashes. Particularly since your officers face the possibility of pursuit situations, we believe that it is important that they have safety belt systems that will effectively protect them in a crash.; I hope this information is of assistance. Please let me know if yo have any further questions.; Sincerely, Jeffrey R. Miller, Chief Counsel |
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ID: aiam2696OpenMr. Norman N. Loper, State Coordinator of Pupil Transportation, Alabama Department of Education, State Office Building, R-515, Montgomery, AL 36130; Mr. Norman N. Loper State Coordinator of Pupil Transportation Alabama Department of Education State Office Building R-515 Montgomery AL 36130; Dear Mr. Loper: This responds to your October 7, 1977, letter to and conversation wit Mr. Roger Tilton of my staff concerning the applicability of the Federal school bus standards to college buses.; The National Highway Traffic Safety Administration has determined tha colleges do not fall within the ambit of the school bus regulations. I am enclosing a copy of a previous letter on this issue. Accordingly, seat spacing in buses used to transport college students can be determined by the particular state in which the bus will be operated.; Your problem appears to be somewhat more complex than the abov description, however, since you require the college bus to be painted yellow, have flashing lights, and be labeled 'school bus.' It is unlikely that any manufacturers will sell you a bus marked and painted as a school bus that does not comply with the Federal school bus requirements. Were they to do this, it would subject them to liability if the bus were misused to transport school children, which from all outward appearances it would be designed to do. We suggest that you label the bus with the name of the college or other institution and drop the 'school bus' designation. This would permit manufacturers to supply the bus without fear of violating Federal requirements.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam5153OpenMr. Carl W. Ruegg President Carlo International, Inc. P.O. Box 250 Selma, CA 93662; Mr. Carl W. Ruegg President Carlo International Inc. P.O. Box 250 Selma CA 93662; Dear Mr. Ruegg: This responds to your letter of March 29, 1993, t Taylor Vinson of this Office. In response to your request for 'information and regulations regarding the importation of non-conforming vehicles for research, investigation, studies, demonstrations,' I enclose a copy of 49 CFR Part 591, the regulation governing the importation of motor vehicles and equipment subject to the regulations of this agency, and a copy of a final rule published March 8, 1993, that amends the regulations. Sections 591.5(j), 591.6(g) (as amended), and 591.7 (as amended) apply to your inquiry. If you have any questions regarding the interpretation of the regulation or amendments, you may contact Mr. Vinson (202-366-5263). Questions regarding the implementation of the regulations, such as the information deemed acceptable to acquire the agency's pre-entry letter of approval, should be addressed to the Office of Vehicle Safety Compliance. You may contact Clive Van Orden with questions of this nature (202-366-2830). Sincerely, John Womack Acting Chief Counsel Enclosure; |
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ID: aiam0351OpenMr. Martin Rothfield, Manager, Quality Assurance, Ideal Corporation, 435 Liberty Avenue, Brooklyn, NY, 11207; Mr. Martin Rothfield Manager Quality Assurance Ideal Corporation 435 Liberty Avenue Brooklyn NY 11207; Dear Mr. Rothfield: In your letter of May 4, 1971, to Francis Armstrong you reques permission to conduct testing of turn signal and hazard warning signal flashers pursuant to SAE Standard J823b, 'Flasher Test Equipment,' April 1968.; Federal Motor Vehicle Safety Standard No. 108 incorporates by referenc SAE Standard J590b, 'Automotive Turn Signal Flashers,' October 1965, and SAE Recommended Practice J945, 'Vehicular Hazard Warning Signal Flasher,' February 1966, both of which specify test circuitry and equipment according to 'SAE J823.' It is my understanding that the major difference between J823 and J823b, which becomes the appropriate sub-referenced standard on January 1, 1972, is the specification in the latter that 'The required voltage tests [for variable-load flashers] with maximum bulb load shall be conducted without readjusting each corresponding power supply voltage, previously set with minimum bulb load.' It appears that J823 was written before variable load flashers were in general use and that this is the reason for omission of this specification from J823. Since J823b includes all the requirements of the presently referenced SAE standard, you may proceed to implement it immediately.; Sincerely, Robert L. Carter, Acting Associate Administrator, Moto Vehicle Programs; |
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ID: aiam1393OpenMr. Lee Moses, Trailer Coach Association, 3855 East LaPalma Avenue, Anaheim, CA, 92806; Mr. Lee Moses Trailer Coach Association 3855 East LaPalma Avenue Anaheim CA 92806; Dear Mr. Moses: This is in response to your telephone request of February 6, 1974 concerning the application of Standard No. 302, *Flammability of Interior Materials.*; The standard applies to passenger cars, multipurpose passenge vehicles, trucks, and buses. It does not apply to trailers, the vehicle category which includes mobile homes and other towed recreational vehicles, but it does apply to motor homes and to those campers that are constructed on new chassis. Accordingly, any of the components listed in paragraph S4.1 that are installed in the occupant compartments of the motor vehicles to which the standard is applicable must meet the standard's requirements.; You also asked whether a State may have a motor vehicle safety standar applicable to vehicles covered by a Federal standard that differs from the requirements of the Federal standard. The answer is no. Under the preemption provision of the National Traffic and Motor Vehicle Safety Act, section 103(d), 15 U.S.C. 1392(d), State motor vehicle requirements, if any, have to be identical to the requirements of the Federal standard. Any differing requirements would be void.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam1669OpenMr. Donald D. Wahlin, President, Stoughton Trailers, 416 South Academy Street, Stoughton, WI 53589; Mr. Donald D. Wahlin President Stoughton Trailers 416 South Academy Street Stoughton WI 53589; Dear Mr. Wahlin: This responds to your October 15, 1974, letter to the Bureau of Moto Carrier Safety asking if a trailer is subject to Standard No. 121, *Air brake systems*, if its buyer certifies, for tax purposes, that the vehicle in fact uses the highways only incidentally.; I have enclosed a discussion of our regulatory authority over moto vehicles, which does not include vehicles intended and sold solely for off-road use. However, we do regulate vehicles which use the highway on a necessary and recurring basis, whether or not this use is infrequent and incidental to the vehicle's working function.; We do not base this distinction on the same considerations as underl excise tax regulations and laws. The statutory definition of 'motor vehicle' and the regulations in the tax area differ from ours, as they are only directed to taxing regular highway users who should bear the burden of maintaining the roads. In contrast, our statute and regulations are directed to safe vehicle design, which is important for all vehicles designed to use the highways, whether or not their use is on a regular basis. We conclude that the revenue considerations involved in tax cases are not relevant to our safety regulation requirements.; Yours truly, Richard B. Dyson, Acting 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.