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: aiam2439OpenMr. Pao-Yeh Hu, Manager, TYM Industries Co., Ltd., No. 2-26, Yeng Hang, Yongkang, Tainan-Hsian, Taiwan; Mr. Pao-Yeh Hu Manager TYM Industries Co. Ltd. No. 2-26 Yeng Hang Yongkang Tainan-Hsian Taiwan; Dear Mr. He: This is in reply to your letter of September 27, 1976, to the Nationa Highway Traffic Safety Administration, concerning lighting requirements for mopeds.; The headlamp must be designed to conform to SAE Standard J584 'Motorcycle and Motor Driven Cycle Headlamps,' April 1964. This Standard does not require a sealed beam headlamp, nor is a minimum wattage specified. Obtaining an AAMVA certificate is probably the best way of insuring that a State raises no obstacles to registry of your vehicle.; There is no minimum wattage for the taillamp or stop lamp. These tw lamps may be combined. There is no Federal requirement for SAE identification, however, most lamps are so identified, because of the requirements in the state of Virginia.; Sincerely, E. T. Driver, Director, Office of Crash Avoidance, Moto Vehicle Programs; |
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ID: aiam0404OpenMr. J. Wuddel, Westfalische Metall Industrie KG, Rusck and Company, 4760 Lippstadt, Postfach 604, Republic of West Germany; Mr. J. Wuddel Westfalische Metall Industrie KG Rusck and Company 4760 Lippstadt Postfach 604 Republic of West Germany; Dear Mr. Wuddel: This is in reply to your letter of July 7, 1971, to the Nationa Highway Safety Bureau (now the National Highway Traffic Safety Administration) concerning the requirements for sealed beam headlamp units.; The answers to your specific questions are as follows: >>>1. Sealed beam units must meet the photometric specifications in SA J579 at the design voltage at or below the maximum amperes specified in SAE J573.; 2. Tolerances are as follows: *Electrical power* - the maximum electrical power is the product, i watts, of the design voltage multiplied by the maximum amperes at design volts. There is no specified minimum electrical power.; *Maximum amperes* - There is no tolerance. Maximum amperes is th maximum specified in SAE J573.; *Design watts* - There is no tolerance. There is, however, a toleranc on the actual watts or electrical power as described above.; 3. & 4. The filament types and positions are illustrative of curren practice only. Any type or position may be used to meet the specifications of J579 and J573.; 5. All glass sealed beam units are not mandatory. There are n restrictions in Federal Motor Vehicle Safety Standard No. 108 or the SAE Standards on the number of pieces or the materials which are used to complete the assembled sealed beam unit as long as the specifications, including those in SAE J571, are met. Caution should be used, however, to ensure that a good and durable seal is obtained between the metal back, if used, and the other parts to optimize the useful service life of the sealed beam unit.<<<; Sincerely, E. T. Driver, Director, Office of Operating Systems, Moto Vehicle Programs; |
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ID: aiam5606OpenPatrick M. Raher, Esq. Hogan & Hartson, L.L.P. Columbia Square 555 Thirteenth Street, N.W. Washington, DC 20004-1109; Patrick M. Raher Esq. Hogan & Hartson L.L.P. Columbia Square 555 Thirteenth Street N.W. Washington DC 20004-1109; "Dear Mr. Raher: This responds to your request for an interpretation o the seat position specifications of Standards No. 208, Occupant Crash Protection, and No. 214, Side Impact Protection. These specifications, which are part of the test conditions for the standards' dynamic crash tests, indicate how a vehicle's seats are positioned in those tests. You asked how the specifications apply in the case of power seats which have different maximum seating locations in the forward and rearward position depending on seat height. As discussed below, the seats would be positioned midway between the forwardmost and rearmost positions (with the forwardmost and rearmost positions being determined irrespective of seat height), and at the lowest possible height at that midway position. This appears to correspond to Option 1 in your letter. In your letter, you described a power seat design whose seat position potential is trapezoidal rather than rectangular, due to the mechanism utilized in the power seat operation. In particular, the seat can move further forward in its highest position than in its lowest position, and further rearward in its lowest position than in its highest position. You also indicated that a lowering of the seat from a higher position has the effect of moving the seat backward. The seat position specifications of Standards No. 208 (S8.1.2) and No. 214 (S6.3) read as follows: Adjustable seats are in the adjustment position midway between the forwardmost and rearmost positions, and if separately adjustable in a vertical direction, are at the lowest position. If an adjustment position does not exist midway between the forwardmost and rearmost positions, the closest adjustment position to the rear of the midpoint is used. This provision sets forth two conditions concerning how an adjustable seat is positioned in a crash test. The first condition, for the longitudinal position of the seat, is for the seat to be in the adjustment position midway between the forwardmost and rearmost positions. The terms 'forwardmost' and 'rearmost' are not qualified by height, so the absolute forwardmost and rearmost positions would be used, irrespective of seat height at those positions. The second condition, for the vertical position of a seat which is separately adjustable in a vertical direction, is for the seat to be in the lowest position. We interpret this to refer to the lowest vertical position that can be attained at the longitudinal position described above. Therefore, in positioning a seat for a crash test, we would not change the longitudinal position of the seat merely because the mechanism was designed so that lowering the seat from a higher position had the effect of moving the seat backward. Instead, we would find the lowest vertical position that could be attained at the specified longitudinal position. I hope this information is helpful. If you have any further questions, please feel free to call Edward Glancy of my staff at 366-2992. Sincerely, John Womack Acting Chief Counsel"; |
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ID: aiam4914OpenMr. Marc M. Baldwin Parker, McCay & Criscuolo Suite 401 Three Greentree Centre Route 73 & Greentree Road Marlton, NJ 08053; Mr. Marc M. Baldwin Parker McCay & Criscuolo Suite 401 Three Greentree Centre Route 73 & Greentree Road Marlton NJ 08053; "Dear Mr. Baldwin: This responds to your September 25, 1991, letter i which you asked 'the specific date when 2-point seatbelts were outlawed.' Lap, or 2-point, belts have never been outlawed by this agency. Rather, 3-point, or lap/shoulder belts have been required at certain seating positions in certain vehicles. Lap belts are still permitted as the only occupant restraint at a seating position in all vehicles at some seating positions. Such seating positions include all seating positions that are not outboard seating positions and all seating positions that are not forward-facing. Your letter mentioned that you are specifically interested in this information for pending litigation regarding a 1984 passenger car convertible. Passenger car convertibles manufactured in 1984 were permitted to have lap belts installed at all seating positions. The following discussion should clarify NHTSA regulations regarding safety belts. S4.1.2 of Standard No. 208 gives vehicle manufacturers a choice of three options for providing occupant crash protection in passenger cars. Option 1, set forth in S4.1.2.1, requires vehicle manufacturers to provide automatic protection at the front outboard seating positions, lap or lap/shoulder safety belts at all other seating positions, and either meet the lateral crash protection and rollover requirements by means of automatic protection systems or have manual safety belts at the front outboard seating positions such that those positions comply with the occupant protection requirements when occupants are protected by both the safety belts and the automatic protection. Option 2, set forth in S4.1.2.2, requires vehicle manufacturers to provide a lap or lap/shoulder safety belt at every seating position, have automatic protection for the front outboard seats, and have a warning system for the safety belts provided. Option 3, set forth in S4.1.2.3, requires the manufacturer to install lap or lap/shoulder safety belts at every seating position and to have a warning system for those belts. Beginning on September 1, 1986, manufacturers were required to begin phasing-in the installation of automatic restraint systems, such as automatic belts and airbag systems, in their passenger cars. For example, S4.1.3.1 of Standard No. 208 required manufacturers to certify that at least ten percent of their passenger cars manufactured on or after September 1, 1986, and before September 1, 1987, complied with S4.1.2.1. S4.1.3.2 required 25 percent of passenger cars manufactured on or after September 1, 1987, and before September 1, 1988, to comply with S4.1.2.1, and S4.1.3.3 required 40 percent of passenger cars manufactured on or after September 1, 1988, and before September 1, 1989, to comply with S4.1.2.1. However, the agency temporarily excluded convertibles from the automatic restraint requirement during the phase-in period. This exclusion meant that convertibles did not have to be counted in the total passenger car production to determine the percentage of total passenger car production equipped with automatic restraints. Instead of automatic restraints, convertibles manufactured prior to September 1, 1989, were allowed to have either a manual lap or lap/shoulder belt at each seating position. All passenger cars, including convertibles, manufactured on or after September 1, 1989, must be certified as complying with S4.1.2.1. There are also currently requirements for lap/shoulder belts in some rear seating positions in convertibles. Again, however, these requirements would not have applied to the 1984 convertible involved in your litigation. For your information, S4.1.4 of Standard No. 208 includes additional requirements for forward-facing rear outboard seating positions in passenger cars. All passenger cars, except convertibles, manufactured on or after December 11, 1989, were required to have lap/shoulder belts at these seating positions. All convertibles manufactured on or after September 1, 1991, are required to have lap/shoulder belts at these positions. I hope this information is helpful. If you have any more questions about this issue, feel free to contact Mary Versailles of my office at this address or by telephone at (202) 366-2992. Sincerely, Paul Jackson Rice Chief Counsel"; |
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ID: aiam2069OpenMr. Tokio Iinuma, Nissan Motor Co., Ltd., 560 Sylvan Avenue, Englewood Cliffs, NJ 07632; Mr. Tokio Iinuma Nissan Motor Co. Ltd. 560 Sylvan Avenue Englewood Cliffs NJ 07632; Dear Mr. Iinuma: This is in response to your letter of September 17, 1975, in which yo ask whether a permanent label affixed to the inside surface of a hubcap would satisfy the requirements of a new proposed paragraph S3.2 of Standard No. 211.; The intent of the proposed labeling requirements, part of a genera identification scheme for motor vehicle equipment manufacturers, is to ensure rapid and efficient identification of the manufacturer of a defective or nonconforming part or vehicle. The placement of an identifying label on the inside of a hubcap would not hinder rapid identification of the manufacturer. Therefore, the National Highway Traffic Safety Administration would consider that a label that is permanently affixed to the inside surface of a hubcap and contains the information specified in proposed paragraph S3.2 of Standard No. 211 would comply with the requirements of S3.2.; We hope this answer is satisfactory. If you have any other questions please contact us.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam0054OpenMr. H.G. Webster, Director and Chief Engineer, The Standard-Triumph Motor Company, Limited, Coventry, England; Mr. H.G. Webster Director and Chief Engineer The Standard-Triumph Motor Company Limited Coventry England; Dear Mr. Webster: #This letter is in response to your February 27 1968, request for approval of equivalent rims for use in the following tire and rim combinations: #>>>A. *Bias Ply Tires* #1. 5.20-13 on 4 1/2J rim. #2. 5.60-13 on 3 1/2J rim. #B. *Radial Ply Tires* #1. 145-13 on 3 1/2J rim. #2. 145-13 on 4 1/2J rim. #3. 185-15 on 4 1/2J rim.<<< #On the basis of the supporting information submitted, your request for approval of the equivalent rims and proposed tire combinations listed above is granted. #Sincerely, George C. Nield, Acting Director, Motor Vehicle Safety Performance Service; |
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ID: aiam2593OpenMr. James M. Beach, Director of Engineering, Collins Industries, Inc., P.O. Box 58, Hutchinson, KS 67501; Mr. James M. Beach Director of Engineering Collins Industries Inc. P.O. Box 58 Hutchinson KS 67501; Dear Mr. Beach: This responds to your April 28, 1977, letter in which you ask severa questions concerning Standard No. 222, *School Bus Passenger Seating and Crash Protection*, and the definition of school bus.; You first ask whether the seat spacing requirements found in S5.2.1 o the standard are applicable to buses with gross vehicle weight ratings (GVWR) equal to or less than 10,000 pounds. Buses in this weight classification do not have to comply with the mandatory seat spacing requirements. Since these buses are equipped with seat belts, the mandatory seat spacing is not necessary to provide adequate occupant crash protection.; Your second question concerns those areas required to meet the hea protection zone requirements. You ask whether the window frame, window supporting structure, and window glass are included within the head protection zone requirements.; The NHTSA issued an amendment of the standard (Notice 6, 41 FR 28506 in an attempt to clarify those portions of the bus subject to the head protection zone requirements. In this notice (copy enclosed), we stated that the sidewall, window and door structures were never intended to be included within the zone and are not subject to the requirements for head protection. However, the roof structure, if it falls within the zone, is subject to the requirements. If you need further information to determine the portions of your bus that would be included within the head protection zone requirements, I suggest that you send the agency sketches of your bus interior depicting those areas of concern.; Concerning seat orientation, you question whether the requirements fo forward facing seats found in S5.1 of the standard applies to buses with GVWR's of 10,000 pounds or less. S5(b) of the standard lists the paragraphs of the standard applicable to buses in the above-mentioned weight classification. S5(b) does not refer to S5.1 which contains the requirement for forward facing seats. This omission was an oversight that occurred during the drafting of the regulation. The agency intended that seats in all school buses be forward facing, unless designed for handicapped or convalescent passengers as permitted in Notice 6. This intent is obvious since, as you note, we require these seats to comply with forward and rearward performance requirements. The NHTSA will soon issue an amendment of the standard to correct this omission.; Your final question concerns the definition of school bus whic excludes common carriers in urban transportation. Your interpretation of this exclusion is correct. These buses are permitted to transport children to and from school but need not comply with the school bus construction standards.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam5256OpenThe Honorable Phil Gramm United States Senate 2323 Bryan Street, #1500 Dallas, TX 75201; The Honorable Phil Gramm United States Senate 2323 Bryan Street #1500 Dallas TX 75201; "Dear Senator Gramm: Thank you for your inquiry on behalf of you constituent, Mr. Thomas J. Devon of Longview, Texas. The Federal Highway Administration (FHWA) referred your inquiry to this office, since the National Highway Traffic Safety Administration (NHTSA) administers Federal safety standards for tires. In his communication with you, Mr. Devon expressed concern about separated treads from retreaded large truck tires. He referred to the deaths of two young women reportedly caused when they lost control of their vehicle after striking a separated tread in the road. Mr. Devon is concerned that retreaded tires do not meet the same standards as new tires and requested data on accidents caused by separated tire tread sections on the roadway. By way of background information, the National Traffic and Motor Vehicle Safety Act of 1966, 15 U.S.C. 1381, et seq. (Safety Act) authorizes NHTSA to issue safety standards applicable to new motor vehicles and new items of motor vehicle equipment. Pursuant to that authority, NHTSA has issued various Federal Motor Vehicle Safety Standards (FMVSS) applicable to tires: FMVSS Nos. 109 and 110 for new pneumatic passenger car tires, FMVSS Nos. 119 and 120 for new pneumatic tires for other than passenger cars, and FMVSS No. 117 for retreaded passenger car tires. There is currently no standard applicable to retreaded tires for vehicles other than passenger cars. This is because the agency is not aware of any data suggesting a safety need for such a standard. With respect to tire tread separation, examination of actual tire scraps from the nation's highways have indicated that about 60 percent came from retreaded tires and 40 percent from original tires. Because of the many complaints about heavy truck tire tread scraps on and around the highways, the University of Michigan conducted a study in the mid-1980s entitled 'Large Truck Accidents Involving Tire Failure.' That study concluded that most large truck tire failures are caused by vehicle overload and/or tire underinflation. Underinflation causes excessive flexing of the tire. The friction resulting from that flexing causes excessive heat buildup which can, in turn, result in tread separation or other tire failure. Indeed, the heat buildup has been known to be so extreme as to cause the tire to burst into flame. The findings from the Michigan study led the FHWA to prohibit the operation of commercial motor vehicles with overloaded and underinflated tires, unless the vehicle is operated pursuant to a special permit issued by a state. That permit, however, requires a reduced speed to compensate for the increased tire loading. In addition, the vehicle and the tires must be maintained in a safe operating condition at all times. FHWA conducts roadside inspection programs to ensure that such requirements are being met. While scraps of tires on the roadway could pose a safety hazard to motorists, this agency has no real world crash data to indicate what percentage of motor vehicle crashes could be attributed to separated tire treads. Our crash data are limited to the general category of tire failure. Please be assured that NHTSA and FHWA, as well as the tire industry itself, are engaged in ongoing efforts to alleviate this problem by appropriate publicity to large truck owners and operators regarding proper tire care and maintenance and by vigorous vehicle inspection programs. I hope this information is helpful. If your constituent has any further questions, he may contact Walter Myers of this office at this address or at (202) 366-2992. Sincerely, John Womack Acting Chief Counsel Enclosure Constituent's Correspondence"; |
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ID: aiam1215OpenMr. Keitaro Nakajima, 1099 Wall Street, West, Lyndhurst, NJ 07071; Mr. Keitaro Nakajima 1099 Wall Street West Lyndhurst NJ 07071; Dear Mr. Nakajima: This is in reply to your letter of July 24, 1973, concerning th meaning of the phrase 'remain in adjustment' in S5.3.5 of Motor Vehicle Safety Standard No. 215. You ask whether this criterion, when applied to the alignment of the front wheels, would permit misalignment as a result of the test, so long as the misalignment could be corrected to within the 'inspection limit' under which vehicle operation is considered to be normal.; Our reply is that impact-related misalignment beyond the inspectio limit is considered to be a noncompliance with S5.3.5, even though a mechanic could bring the wheel within the inspection limit without recourse to extraordinary techniques. Some variance in alignment would be permitted, in that tests are begun with the wheels aligned as closely as possible to the manufacturer's nominal adjustment limit which may be tighter than the inspection limit. This variance, however, is considerably less than what you envision in your letter.; Yours truly, Richard B. Dyson, Assistant Chief Counsel |
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ID: aiam3228OpenMr. David Williams, Box 4091, Wilmington, DE 19807; Mr. David Williams Box 4091 Wilmington DE 19807; Dear Mr. Williams: I would like to clarify my remarks of March 17, 1980, with respect t the applicability of Federal motor vehicle safety standards to imported vehicles.; In that letter I implied that there was a prohibition against importin cars that didn't meet Federal standards and that such vehicles had to comply with standards in effect on the date of importation. Actually, a non-conforming vehicle may be imported under bond if it will be brought into compliance within 120 days of entry with all applicable standards in effect on the date of its manufacture.; 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.