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: aiam4620OpenMs. Gay M. Arthur 20096 Park Hill Dr. Barrington, IL 60010; Ms. Gay M. Arthur 20096 Park Hill Dr. Barrington IL 60010; Dear Ms Arthur: This is in reply to your letter to Taylor Vinson o this Office. You have asked if 'detachable, lighted novelty items are legally allowable on passenger cars,' specifically 'for the exterior roof.' You appear to have in mind an item of aftermarket equipment, that is to say, an item which is not original equipment on a car, but one that the vehicle owner purchases during the course of his ownership. There is no restriction under Federal law as to roof-mounted novelty items if they are installed by the vehicle owner. If they are installed by a manufacturer, distributor, dealer, or motor vehicle repair business, they are permissible as long as they do not render inoperative, in whole or in part, equipment that is installed pursuant to a Federal motor vehicle safety standard. For example, if installation of the novelty light affected the wiring and hence the performance of lighting equipment installed on the vehicle by its manufacturer, that would be a 'rendering inoperative' within the meaning of the prohibition. Use of the novelty light would be determined by the laws of a State in which it is operated. We are unable to advise you on State laws, and suggest that, for further information, you consult the American Association of Motor Vehicle Administrators, 4600 Wilson Boulevard, Arlington, VA 22203. Sincerely, Stephen P. Wood Acting Chief Counsel; |
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ID: aiam1422OpenMr. C. W. Mohr, Vice President-Marketing, Certain-Teed Products Corporation, 2901 Lakeview Road, P.O. Box 366, Lawrence, KS 66044; Mr. C. W. Mohr Vice President-Marketing Certain-Teed Products Corporation 2901 Lakeview Road P.O. Box 366 Lawrence KS 66044; Dear Mr. Mohr: This responds to your January 25, 1974, question whether failure of 'common' clampband assembly on the 'Camtite' emergency and parking spring brake, which would cause complete loss of air to the service brake system and failure of the emergency/parking brake portion of one unit, would be in violation of paragraph S5.7.2.2 of Standard 121.; The answer is no. S5.7.2.2 requires that failure of components commo to the service and emergency braking systems shall not result in a loss of air that causes the parking brake to be inoperable. We interpret 'parking brake' to mean the entire parking brake system. The failure you describe would not render the entire system inoperable, because all parking brakes other than the affected unit would remain operable.; This letter will be placed in the public file for the information o other interested persons.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam5461OpenMr. Tom Determan Engineering Manager Brownie Tank Mfg. Co. 1241 - 72nd Ave. N.E. Minneapolis, MN 55432; Mr. Tom Determan Engineering Manager Brownie Tank Mfg. Co. 1241 - 72nd Ave. N.E. Minneapolis MN 55432; Dear Mr. Determan: This is in reply to your letter of September 2 1994, to Taylor Vinson of this Office. You have inquired about the mounting height requirements specified in Motor Vehicle Safety Standard No. 108 for side marker lamps and reflex reflectors installed on tank trucks. You understand that 'side marker lamps must be mounted at any height above 15' from ground level, and reflex reflectors must be mounted between 15' and 60' from ground level.' You are correct. Standard No. 108 (Tables II and IV) specifies that side reflex reflectors on trucks shall be mounted not less than 15 inches nor more than 60 inches above the road surface, and that side marker lamps must be mounted not less than 15 inches above the road surface. This means that side marker lamps may be placed at heights greater than 60 inches. Noting your thought that enforcement personnel are mistakenly applying requirements for trailers to tank trucks of your customers, I would like to say that the requirements are the same for trailers, except that, under Table II which applies to trailers whose overall width is 80 inches or more, the rear side marker lamps are subject to the same 60-inch height limitation as the side reflex reflectors. I hope that this is helpful in resolving your problem. Sincerely, Philip R. Recht Chief Counsel; |
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ID: aiam0399OpenMr. Fred W. Cords, O.E.M. Marketing Manager, Minnesota Automotive, Inc., 502 Patterson Avenue, Mankato Minnesota 56001; Mr. Fred W. Cords O.E.M. Marketing Manager Minnesota Automotive Inc. 502 Patterson Avenue Mankato Minnesota 56001; Dear Mr. Cords: This is in reply to your letter of June 29 asking whether th installation of MICO brake locks, as a supplemental parking brake system, is acceptable to the National Highway Traffic Safety Administration.; We understand that the MICO brake lock is used only in hydraulic brak systems of trucks. There is no Federal motor vehicle safety standard currently in effect covering truck hydraulic brake systems, and installation of MICO brake locks by a dealer, prior to first sale of a vehicle, is permissible as long as the lock does not impair conformance of brake hoses and brake hose assemblies with Federal Motor Vehicle Safety Standard No. 106. That the installation might impair conformance is inferred in the Chevrolet Dealer letter, DD-1412, May 10, 1971, which you enclosed.; A proposal has been issued (Docket No. 70-27) that would require truck equipped with hydraulic brake systems to meet certain performance requirements, effective with trucks manufactured on or after October 1, 1972. If this proposal is adopted as a Federal standard, installations of the MICO supplemental brake system on a truck, by a dealer, prior to first sale of a vehicle would be allowable as long as the installation does not affect conformance of the required mechanical parking brake system with Federal requirements, or with Standard No. 106.; Sincerely (signature illegible) |
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ID: aiam1971OpenD. R. Bernard, Esq., Messrs. Bernard & Bernard, 4100 One Shell Plaza, Houston, TX 77002; D. R. Bernard Esq. Messrs. Bernard & Bernard 4100 One Shell Plaza Houston TX 77002; Dear Mr. Bernard: This is in reply to your letter of May 28, 1975, providing furthe information for our determination whether certain 'safety lights' would violate the National Traffic and Motor Vehicle Safety Act of 1966.; There is no Federal prohibition against sale of this accessory in th aftermarket. It would, however, be subject to regulation by the states. For the following reasons, it could not be used as original equipment. Standard No. 108 requires a minimum spacing of 4 inches (edge to edge) between the stop lamps and the rear turn signal lamps and a minimum spacing of 9 inches (centerline to centerline) between the turn signals. The purpose of this spacing is to provide a distinctive indication of the turning direction. A flashing stop lamp located in close proximity to the steady-burning stop lamp required by Standard No. 108 would, in our opinion, impair the effectiveness of the rear turn signal within the meaning of S4.1.3, during a combined braking and turning operation. Such a lamp would also be prohibited by S4.6(b) which, in effect, requires all original equipment stop lamps to be steady burning.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam0663OpenMr. Louis C. Lundstrom, Director, Automotive Safety Engineering, General Motors Technical Center, Warren, MI 48090; Mr. Louis C. Lundstrom Director Automotive Safety Engineering General Motors Technical Center Warren MI 48090; Dear Mr. Lundstrom:This is in reply to your letter of February 28 1972, in which you asked to be referred to the information on which we based our statement in the notice of February 24, 1972, that systems meeting the injury criteria of Standard 208 are available using current seat belt technology.; Research data on the capabilities of seat belts are found in severa places in the public docket, notably in the progress reports from our Safety Systems Laboratory and from Cornell Aeronautical Laboratory (69-7 General Reference Nos. 74, 75, 83, 96, 102, 117, 120 and 135). There are records of vehicle tests in which current lap and shoulder belt systems have met the injury criteria (see, e.g. N13-69-7-20, N13-69-7-37). Also, the record contains information on energy absorbing webbing and anchorages, both of which are improvements within the current state of the art (see, for example, the 6th progress report from Cornell, runs no. 625-630, 69-7 General Reference No. 135, the data from Toyota in N13-69-7-23, and the Takata Koyjo data in N16-69-7-1).; Although the behavior of the head seems to be a greater problem fo belt systems than the behavior of the chest, due in part to the effects of rebound, the changes in the head injury criteria proposed in Notice 17 should ease the problem considerably.; Sincerely, Douglas W. Toms, Administrator |
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ID: aiam5031OpenMr. Michael F. Hecker Micho Industries P.O. Box 1791 Goleta, CA 93116; Mr. Michael F. Hecker Micho Industries P.O. Box 1791 Goleta CA 93116; "Dear Mr. Hecker: This responds to your letter of June 8, 199 concerning how the 'R-Bar' should be positioned during testing under Standard No. 222, School bus passenger seating and crash protection. The R-BAR is a padded restraining device, and the ends of the device attach to the rear of a school bus seatback. The device folds down for the purpose of restraining the passengers seated in the next rearward seat. Your letter states that, under the test condition set forth in S6.4 of the standard, you believe that the test should be performed with the R- Bar in its most upright position. As discussed below, your understanding is incorrect. Section S6 of Standard No. 222 sets forth a number of test conditions which apply to the requirements specified in section S5 of the standard. One of these requirements, set forth in section S6.4, reads as follows: 'If adjustable, a seat back is adjusted to its most upright position.' This test condition addresses seat backs which may be adjusted to different angles for the comfort of the seat occupant. Your letter raises the issue of whether this condition also addresses the position of a restraining bar which is attached to the seat back. It is our opinion that S6.4 only addresses the position (degree of uprightness) of a seat back as a whole, and not the position of individual components that can separately be placed in different positions without affecting the degree of uprightness of the seat back. In the case of the R-Bar, the position of the R- Bar (up or down) has no effect on the degree of uprightness of the seat back. Therefore, Standard No. 222 does not expressly address the position of a device such as the R-Bar. As a general matter, when a standard does not specify a particular test condition, there is a presumption that the requirements of the standard must be met at all such test conditions. This presumption that the standard must be met at all positions of unspecified test conditions may be rebutted if the language of the standard as a whole or its purposes indicate an intention to limit unspecified test conditions to a particular condition or conditions. In the case of Standard No. 222, nothing in the language of the standard suggests that the test procedures is only to be performed with a device such as the R-Bar in only one particular position. Indeed, the purpose of the standard is to reduce the possibility of death or injury to school bus occupants during crashes and sudden driving maneuvers. To serve this purpose, the vehicle must be capable of meeting the requirements of Standard No. 222 with the R-Bar in any position in which it may be placed, since the R-Bar could be at any such position when the seat is occupied. I hope you find this information helpful. If you have any other questions, please contact Mary Versailles of my staff at this address or by phone at (202) 366-2992. Sincerely, Paul Jackson Rice Chief Counsel"; |
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ID: aiam0233OpenMr. Donald B. Haaversen, 2833 Harriet Avenue, South, Minneapolis, Minnesota 55408; Mr. Donald B. Haaversen 2833 Harriet Avenue South Minneapolis Minnesota 55408; Dear Mr. Haaversen: Thank you for your letter of March 9, 1970, to the National Highwa Safety Bureau, concerning our Federal motor vehicle tire standards.; The only tire standard promulgated to date is Federal Motor Vehicl Safety Standard No. 109, 'New Pneumatic Tires-Passenger Cars' which was effective January 1, 1968. This standard specifies minimum performance for size, strength, endurance, high speed laboratory testing and labeling. For your information, I have enclosed a copy of Standard No. 109 and No. 110 with amendments.; The replies to your specific questions are as follows: >>>1. *Question:* New American made tires have DOT load ranges, loa capacity and inflation pressures molded into the sidewall. Is this required (that they be *permanently* marked), or is it sufficient to affix a temporary marking (such as a sticker) with this same information?; *Response:* Section S4.3 states that this information shall b permanently molded into or onto all new passenger car tires manufactured after August 1, 1968. If the tire was manufactured between January 1, 1968 and July 31, 1968 the labeling requirements may be met by use of a label or tag.; 2. *Question:* How is load capacity information arrived at? Is it b manufacturer certification, government conducted tests, or some other method?; *Response:* The load/inflation schedule is calculated by use o empirical formulas and coordinated through the various Tire and Rim Associations as well as the Society of Automotive Engineers.; 3. *Question:* Is it necessary that these tires be subject to safet tests? These particular tires are already imported by another organization and may already have passed the necessary tests, if any.; *Response:* The application of the 'DOT' recital to a tire, is the tir manufacturers self certification that his tire conforms to all the minimum performance standards of Federal Motor Vehicle Safety Standard No. 109.<<<; I have also enclosed for your review and information the followin data:; >>>1. U.S. Customs Regulations for Importation of Motor Vehicles an Items of Motor Vehicle Equipment.; 2. Automobiles Imported Into the United States.<<< Sincerely, Rodolfo A. Diaz, Acting Associate Director, Motor Vehicl Programs; |
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ID: aiam4509OpenTerry K. Brock, National Sales Manager Coons Manufacturing Inc. 2300 West Fourth Street/Box 489 Oswego, KS 67356; Terry K. Brock National Sales Manager Coons Manufacturing Inc. 2300 West Fourth Street/Box 489 Oswego KS 67356; "Dear Mr. Brock: This is a response to your letter of last year seekin an interpretation of Standard 217, Bus Window Retention and Release (49 CFR 571.217). I apologize for the delay in this response. Specifically, you asked whether the front entrance door of a bus may be considered as an emergency exit under Standard 217. You stated that some of your company's buses have the front entrance door labeled as an emergency exit, and equipped with the emergency release mechanism required by Standard 217. You enclosed an August 28, 1987 letter from the New Jersey Department of Transportation referencing Federal Motor Carrier Safety Regulations that 'require...emergency exits (to) comply with' Standard 217. The letter from New Jersey states that a 'front entrance door cannot be considered (as an emergency exit) since the intent of the regulations is to provide emergency escape through push out windows and roof escape hatches.' You asked whether we interpret Standard 217 as precluding front entrance doors from also serving as emergency exits. The answer to your question is no. As long as the front door meets all applicable requirements for emergency exits under Standard 217, the door can be considered as an emergency exit. Contrary to the opinion stated in the New Jersey letter, it never has been this agency's position that only push-out window and roof exits may be used to satisfy Standard 217 requirements. (See 37 FR 9394, 9395, May 10, 1972, copy enclosed.) The question of whether a front entrance door may be a required emergency exit under Standard 217 depends upon (1) the vehicle's gross vehicle weight rating (GVWR), and (2) whether the vehicle is a school bus, or a bus other than a school bus. I will address each of the possibilities separately. Bus Other Than a School Bus, and With a GVWR of More Than 10,000 Lbs. A front entrance door can serve as a required emergency exit under Standard 217 in a bus that is not a school bus, and that has a GVWR of more than 10,000 pounds. For such buses, paragraphs S5.2.1 and S5.2.1.1 of Standard 217 generally require the bus to have 'side exits and at least one rear exit,' or 'one side door for each three passenger seating positions.' If the bus configuration precludes installing an accessible rear exit, then a manufacturer may install a roof exit under the conditions set out in S5.2.1. Bus Other Than a School Bus, and With a GVWR of 10,000 Lbs. or Less A front entrance door can also serve as a required emergency exit for buses other than school buses with a GVWR of 10,000 pounds or less. For these buses, the vehicle must have windows or other emergency exits that meet the requirements set out in paragraphs S5.2.2, or S5.3 through 5.5 of the Standard. If the vehicle's emergency exits are standard, roll-down windows, or the vehicle's entrance and exit doors, then these exits must meet the specifications of S5.2.2(b). Under that provision, the windows and doors must be manually operable, and must open to a position that provides a specified area for getting out. Note that under S5.5.1, these exits do not have to meet Standard 217 marking requirements. The agency has determined that people who are old enough to read instructions generally are familiar with the operation of standard, roll-down windows and doors, and that there is little justification for requiring emergency exit markings for these exits. (40 FR 17266, April 18, 1975.) If the vehicle's emergency exits are push-out windows or some other emergency exit, then the vehicle must comply with paragraphs S5.3 through S5.5. A manufacturer must label these exits under S5.5 because they are specially-installed emergency exits whose means of operation may not be obvious to the passengers. School Buses A front entrance door can not serve as a required emergency exit in a school bus, regardless of the vehicle's weight. Paragraph S5.2.3 of Standard 217 requires all school buses to have either (1) one rear emergency door, or (2) 'one emergency door on the vehicle's left side that is in the rear half of the bus passenger compartment and is hinged on its forward side, and one push-out window.' A manufacturer who chooses to meet school bus emergency exit requirements under the second option could not use the front entrance door as a required emergency exit under Standard 217, since that door would not be in the rear half of the passenger compartment. However, if a manufacturer chose to install an 'additional' emergency exit such as a front entrance door, NHTSA regulations would not prohibit installing this exit. As the agency long has held, any 'extra' emergency exit installed in a school bus must comply with Standard 217 provisions applicable to emergency exits in buses other than school buses. Please understand that this letter addresses only Standard 217, and does not address or interpret any Federal Motor Carrier regulations. If you have any questions about those regulations, you should contact the Federal Highway Administration. I hope you find this information helpful. If you have further questions, please contact Joan F. Tilghman of my staff, at (202) 366-2992. Sincerely, Erika Z. Jones Chief Counsel Enclosure"; |
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ID: aiam3736OpenJohn G. Sims, Federal Compliance Engineer, Champion Home Builders Co., Dryden, MI 48428; John G. Sims Federal Compliance Engineer Champion Home Builders Co. Dryden MI 48428; Dear Mr. Sims: This responds to your letter to Mr. Kratzke of my staff, concerning th emergency exit requirements of Safety Standard No. 217, *Bus window retention and release*, that apply to a 22 passenger bus with a gross vehicle weight rating in excess of 10,000 pounds. You indicated that your company counts the area provided by side doors in determining the total emergency exit openings for these buses. However, a state regulatory agency has advised you that side doors may not be used in computing the total emergency exit area required by S5.2 of Standard No. 217. Your letter stated that the state regulatory agency believes that the emergency exit opening for side exits must be provided by windows. The state regulatory agency is incorrectly interpreting the requirements of Standard No. 217 if they hold the position you have stated.; Section S5.2 of Standard No. 217 specifies requirements for th provision of emergency exits for buses, and S5.2.1 sets forth more specific requirements for buses with a gross vehicle weight rating of more than 10,000 pounds. As long as side doors meet all requirements applicable to emergency doors in Standard No. 217, they can be considered emergency exits for purposes of compliance with that standard. The agency has stated this position in several past interpretations, and has never indicated that only window emergency exits could be considered as side exits for purposes of compliance with section S5.2.1.; Should you have any further questions or need further information i this area, please contact Mr. Kratzke at this address, or by telephone at (202) 426-2992.; Sincerely, Frank Berndt, 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.