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: aiam1322OpenMr. William A. Teeling, Somerset Motors Inc., U.S. Highway 22, White House, NJ 08888; Mr. William A. Teeling Somerset Motors Inc. U.S. Highway 22 White House NJ 08888; Dear Mr. Teeling: This is in reply to your letter of October 15, 1973, concerning th means by which you can establish that the odometer on a car you have purchased has been reset.; Without detailed information about the car and about the circumstance which lead you to believe that the odometer has been altered, we can only offer a broad outline of the possible methods of proof. One source might be a former owner who had registered more miles on the odometer when he sold the car than are shown upon subsequent resale. Another source might be a repair shop or service station that had worked on the car and recorded its earlier mileage. A third source would be physical evidence on the car itself: excessive engine wear, excessive brake lining wear, or physical marks of tampering on the odometer or odometer cables. We would be interested to learn of the outcome of your situation.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam4347OpenMr. Thomas Baloga, Safety Engineering, Mercedes-Benz of North America, Inc., P.O. Box 350, Montvale, NJ 07645; Mr. Thomas Baloga Safety Engineering Mercedes-Benz of North America Inc. P.O. Box 350 Montvale NJ 07645; Dear Mr. Baloga: Thank you for your letter of May 28, 1987, to Stephen Oesch of my staf concerning the requirements of Standard No. 301 *Fuel System Integrity*. You noted that there is a conflict in the standard about the correct ground clearance of the contoured impact surface used in the school bus impact test of the standard. You noted that S7.5.1 of the standard refers to the dimension between the ground to the lower edge of the impact surface as 5.25 + 0.5 inches, while figure 2 of the standard shows the ground clearance to be 12.25. As discussed below, the correct dimension is 5.25 + 0.5 inches.; The agency adopted the use of the contoured barrier in a final rul issued on April 16, 1975. The preamble to the final rule stated that 'The contoured barrier would incorporated the moving barrier specification of SAE Recommended Practice J972a (March 1973). However, the impact surface of the barrier would be at a height 30 inches above the ground level, rather than 37 inches as specified in the SAE provision. Studies have shown that a 30- inch test height is more representative of actual collisions. This would be a typical engine height of vehicles that might impact a school bus.' Thus, in S7.5.1 of the standard, the agency adopted the ground clearance as 5.25 inches + 0.5 inches to ensure that the top of the barrier would be 30 inches from the ground. In Figure 2, the agency apparently incorporated the barrier dimensions directly from the SAE Recommended Practice J972a, without changing the ground clearance dimension; We will publish an amendment to the standard that will correct th ground clearance dimension set out in Figure 2 of Standard No. 301.; If you have any further questions, please let me know. Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam0304OpenMr. Charles O. Verrill, Patton, Blow, Verrill, Brand & Boggs, 1200 17th Street, N.W., Washington, DC 20036; Mr. Charles O. Verrill Patton Blow Verrill Brand & Boggs 1200 17th Street N.W. Washington DC 20036; Dear Mr. Verrill: This is in reply to your letter of February 16, 1971, concerning th Tire Identification and Record Keeping Regulations, and your letter of March 12, 1971 submitting additional information.; Section 574.10 requires manufacturers to keep records of tires shippe 'on or in' a vehicle. This would cover the case you describe of tires shipped on a trailer, whether attached to the axle or merely strapped to the frame, providing that the tires were meant for use on that particular trailer.; If the tires are shipped separately, either attached to another traile or shipped in a separate package, they are not considered to be shipped 'on or in' the trailer within the meaning of section 574.10. Therefore, the provisions of section 574.9(b) would apply and the dealer would be required to record the appropriate tire information and communicate it to the tire manufacturer.; If the tires are shipped separately, under Part 574 the traile manufacturer would not be required to keep the records of the tires shipped. However, under section 113(f) of the National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1402), the manufacturer is responsible for maintaining the name and address of the first purchaser. A copy of the Act and the recent amendment to the Act, section 113, which added subsection (f), are enclosed for your information.; Should you so desire, you may submit a petition for rulemaking on thi subject under our rulemaking procedures (49 CFR 553).; Sincerely, Lawrence R. Schneider, Acting Chief Counsel |
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ID: aiam1848OpenMr. G. Meier, Technical Service Manager, Volkswagen of America, Inc., Englewood Cliffs, NJ 07632; Mr. G. Meier Technical Service Manager Volkswagen of America Inc. Englewood Cliffs NJ 07632; Dear Mr. Meier: This is in reference to your safety defect notification and remed campaign (NHTSA No 75-0022) concerning a nut used to secure the front exhaust pipe bracket to the automatic transmission housing which may loosen.; The letter which you have sent to the owners of the subject vehicle does not entirely meet the requirements of section 153 of the 1974 amendment to the National Traffic and Motor Vehicle Safety Act of 1966. Specifically, your letter fails to inform recipients that they may notify the Secretary of Transportation if they are unable to have the defect remedied without charge, as required by section 153(a)(6). The address for this purpose may be given as: Administrator, National Highway Traffic Safety Administration, Washington, D. C. 20590. We also believe that your statement, 'although the possibility of a fire is remote,' is a disclaimer, and is prohibited by 49 CFR S577.6. Likewise use of the word 'may' in your second sentence implies that possibly a defect does not exist and is therefore also prohibited. Your letter also fails to contain an evaluation of the risk to motor vehicle safety as required by section 153(a)(2).; It is therefore necessary that you revise the owner notification lette and send a copy to each owner whose vehicle has not yet been corrected. A copy should also be sent to this office.; If you desire further information, please contact Messrs. W. Reinhar or James Murray of this office at (202) 426-2840. A copy of the 1974 amendment is enclosed.; Sincerely, Andrew G. Detrick, Director, Office of Defect Investigation, Motor Vehicle Programs; |
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ID: aiam2774OpenMr. Philip A. Hutchinson, Jr., Volkswagen of America, 475 L'Enfant Plaza, S.W., Suite 2450, Washington, DC 20024; Mr. Philip A. Hutchinson Jr. Volkswagen of America 475 L'Enfant Plaza S.W. Suite 2450 Washington DC 20024; Dear Mr. Hutchinson: This responds to your January 30, 1978, request for confirmation tha no requirement in S 581.5(c) of the Part 581 *Bumper Standard* limits damage to the supporting ribs inside a plastic bumper face bar component or to the bumper face bar reinforcement component of the bumper system that lies within and reinforces the bumper face bar itself. You also requested confirmation that bumper 'end cuffs' are part of a bumper face bar if they are impacted by the impact ridge of the pendulum test device.; As we understand your description of the bumper reinforcement, it i not a bumper face bar, an exterior surface of the vehicle, or one of the other regulated portions of the vehicle. Therefore, it would not be regulated by the standard.; Internal deformation or cracking of the bumper face bar component doe not violate the provisions of S 581.5(3) as long as the dent and set requirements of (c)(11) are otherwise met.; 'Bumper face bar' is defined in S4 as 'any component of the bumpe system that contacts the impact ridge of the pendulum test device.' Protective ends or cuffs on a steel bumper face bar are considered components of the bumper system and, if contacted by the impact ridge of the pendulum test device, qualify under the definition as a portion of the bumper face bar subject to the same damageability limits as the rest of the bumper face bar.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam5296OpenMr. Don Vierimaa Truck Trailer Manufacturers Association 1020 Princess Street Alexandria, VA 22314; Mr. Don Vierimaa Truck Trailer Manufacturers Association 1020 Princess Street Alexandria VA 22314; Dear Mr. Vierimaa: This responds to your FAX of January 11, 1994, t Pat Boyd of this agency requesting an interpretation of the trailer conspicuity requirements of Standard No. 108. In the future, please address your requests for interpretations to the Chief Counsel. You have asked 'may a manufacturer install a 4 inch (100 mm) wide retrofrelective sheeting instead of 2 inch (50 mm) sheeting on the side of new trailers?' Paragraph S5.7.1.3(d) of Standard No. 108 states that retroreflective sheeting shall have a width of 50 mm (Grade DOT-C2), 75 mm (Grade DOT-C3), or 100 mm (Grade DOT-C4). Paragraph S5.7.1.4.2(a), as amended on October 6, 1993 (58 FR 52021 at 52026), sets forth the requirements for application of retroreflective sheeting to the side of trailers. Without elaboration, it simply identifies it as 'a strip of sheeting.' This means that the manufacturer of the trailer is permitted his choice of Grade DOT-C2, -C3, or -C4 material. Therefore, a manufacturer may install sheeting that has a width of 100 mm on the side of a trailer. Sincerely, John Womack Acting Chief Counsel; |
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ID: aiam1318OpenHonorable John B. Conlan, House of Representatives, Washington, DC 20515; Honorable John B. Conlan House of Representatives Washington DC 20515; Dear Mr. Conlan: This will supplement the Bureau of Motor Carrier Safety's reply o October 30, 1973, to your letter of September 21, 1973, to the Interstate Commerce Commission, concerning Mr. William H. Arendell's automatic light-blinking device for truck signaling. The Bureau has referred your letter to us for further reply.; Enclosed for your constituent's information is a copy of Federal Moto Vehicle Safety Standard No. 108, entitled, 'Lamps, Reflective Devices and Associated Equipment.' The effect of paragraph S4.6 of the standard is to prohibit the use of automatic flashing clearance lamps for signaling purposes on vehicles manufactured on or after January 1, 1972. The term 'flash' is defined (paragraph S3) as 'a cycle of activation and deactivation of a lamp by automatic means continuing until stopped either automatically or manually.'; It appears that the device described in your constituent's letter fall within the prohibition of Standard No. 108, and could not be used as original equipment on vehicles. Its use as an aftermarket device would be subject to regulation by the individual States.; I trust the above information will be of interest to Mr. Arendell. Sincerely, Robert L. Carter, Associate Administrator, Motor Vehicl Programs; |
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ID: aiam2525OpenMr. Sergio Campanini, Vice President and General Manager, The Berg Manufacturing Company, Iola, KS 66749; Mr. Sergio Campanini Vice President and General Manager The Berg Manufacturing Company Iola KS 66749; Dear Mr. Campanini: This responds to Berg Manufacturing Company's February 9, 1977, reques for confirmation that the emergency and parking brake requirements for trailers contained in Standard No. 121, *Air Brake Systems*, would be satisfied by use of an emergency relay valve (ERV) that, upon a single failure in the service brake system upstream from the ERV, automatically directs the application of service brake air through the antilock valve to service brake chambers in proportion to the amount of air loss being experienced. While parking brake force is supplied first by service brake air and subsequently by means of spring brakes, the spring brake force is not utilized until service brake air pressure is lost in the service brake chamber. This occurs because the spring brakes are held off directly by service reservoir air pressure without provision of an isolated reservoir, controlled by a separate valve that directs spring brake application in response to loss of air pressure in the supply line.; From your description, it does not appear that the system complies wit S5.2.1.1 of Standard No. 121. Section S5.2.1.1 specifies that a reservoir shall be provided on a trailer that is capable of releasing the vehicle's parking brakes at least once and that is 'unaffected by loss of air pressure in the service brake system.' This requirement has been interpreted to mean that a single failure of the service brake system would not result in loss of the isolated air supply. A copy of this interpretation is enclosed for your information. It appears that a single failure of the service brake reservoir in the system you describe would result in the loss of the isolated air required by S5.2.1.1.; In other respects the system you describe does not appear to violat the requirements of Standard No. 121. The use of service air pressure to actuate the parking brakes has been used in certain bus applications and is permissible as long as a source of energy to apply the parking brakes is usable at all times and is unaffected by any single failure in the service brake system.; Sincerely, Frank Berndt, Acting Chief Counsel |
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ID: aiam2508OpenMr. W. G. Whitehead, Manager, Product Safety and Regulatory Affairs, Union Carbide Corporation, 270 Park Avenue, new York, N.Y. 10017; Mr. W. G. Whitehead Manager Product Safety and Regulatory Affairs Union Carbide Corporation 270 Park Avenue new York N.Y. 10017; Dear Mr. Whitehead: This responds to your January 31, 1977, question whether Safet Standard No. 116, *Motor Vehicle Brake Fluids*, currently requires a border around the safety warnings that are required to be placed on brake fluid containers.; Standard No. 116 was recently amended (41 FR 54942, December 16, 1976 to specify color coding requirements for hydraulic brake system fluids and to make a minor change in the required warning label. The proposal preceding this amendment did specify that the safety warnings on brake fluid containers be surrounded by a color coded border (40 FR 56928, December 5, 1975). However, after reviewing the comments submitted regarding the cost of the proposed borders and after reevaluating the expected safety benefits, the agency has decided to withdraw the proposed requirements. The final rule, therefore, did not include a requirement for color borders.; Although Standard No. 116 does not require a border around the safet warnings on brake fluid containers, manufacturers are permitted to use a border if they choose.; Sincerely, Frank Berndt, Acting Chief Counsel |
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ID: aiam3638OpenMr. T. Asai, Manager, Tokai Rika Co., Ltd., New York Office, One Harmon Plaza, Secaucus, NJ 07094; Mr. T. Asai Manager Tokai Rika Co. Ltd. New York Office One Harmon Plaza Secaucus NJ 07094; Dear Mr. Asai: THis responds to your letter of October 15, 1982, asking about Federa Motor Vehicle Safety Standard No. 101, *Controls and Displays*. Your letter concerned the symbols specified by that standard for the windshield defrosting and defogging system control and the rear window defrosting and defogging system control. You asked whether it is permissible to use the symbols specified by EEC Directive 78/316/EEC for those controls, stating that there are only slight differences between the symbols specified by Standard No. 101 and the EEC directive. As explained below, the answer to your question is yes.; The preamble to the final rule establishing current Standard No. 10 explained that minor deviations are allowed from the symbols designated by the standard, as long as the symbol used substantially resembles that specified in the standard. 43 FR 27541, June 26, 1978. (This statement was noted in your letter.); For the windshield defrosting and defogging system control, both ou standard and the EEC directive specify three curving arrows (representing rising air) superimposed on a form representing a windshield. For the rear window defrosting and defogging system control, both documents specify three curving arrows superimposed on a form representing a rear window. The forms representing the windshield and the rear window are the same for both Standard No. 101 and the EEC directive. Further, the three curving arrows are superimposed over the windshield or rear window by both documents in the same manner. The only apparent difference between the symbols specified by the two documents is the number of curves in each of the three arrows. The arrows specified by the EEC directive have two curves each, while the arrows specified by Standard No. 101 have three curves.; In our opinion, the deviation you described falls within the intent o the June 1978 statement to permit symbols that are identical to the pictured ones except in some minor respect. The deviation is indeed minor since one must closely examine the two EEC symbols in question and those specified by Standard No. 101 to determine if there is any difference at all.; Sincerely, Frank Berndt, Chief Counsel |
Request an Interpretation
You may email your request to Interpretations.NHTSA@dot.gov or send your request in hard copy to:
The Chief Counsel
National Highway Traffic Safety Administration, W41-326
U.S. Department of Transportation
1200 New Jersey Avenue SE
Washington, DC 20590
If you want to talk to someone at NHTSA about what a request for interpretation should include, call the Office of the Chief Counsel at 202-366-2992.
Please note that NHTSA’s response will be made available in this online database, and that the incoming interpretation request may also be made publicly available.