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: 86-1.16OpenTYPE: INTERPRETATION-NHTSA DATE: 02/03/86 FROM: AUTHOR UNAVAILABLE; Erika Z. Jones; NHTSA TO: Mr. Donald L. Stephens TITLE: FMVSS INTERPRETATION TEXT:
February 3, 1986 Mr. Donald L. Stephens Paccar Technical Center 1261 Highway 237 Mount Vernon, Washington 98237 Dear Mr. Stephens: This responds to your letter of September 13, 1985, asking two questions regarding the legality of an air brake system which proportions the amount of air brake pressure delivered to the drive axles of a tandem drive tractor. By "proportions", you refer to the reduction of the applied air pressure at all treadle positions in rough proportion to the load carried by the tires. Your first question is whether an air brake system such as the one you described would be legal if it otherwise complies with Standard No. 121, Air Brake Systems, (49 CFR 571.121). You also would like to know if it would be legal for you to remove the front axle limiting valve in the design you propose. By way of background information, this agency does not give approvals of motor vehicles or equipment. The National Traffic and Motor Vehicle Safety Act places the responsibility on the manufacturer to ensure that its vehicles or equipment comply with all applicable requirements. A manufacturer then certifies that its vehicles or equipment comply with all applicable requirements. The following represents our opinion based on the facts provided in your letter. In response to your first question, the NHTSA's regulations do not address the matter of proportioning. Standard No. 121 does not specify the design of brake system components; rather, it establishes a performance level. A brake system which proportions the amount of air brake pressure delivered to the drive axles of a tandem drive tractor is not prohibited if it otherwise meets Standard No. 121. As to your second question, NHTSA regulations do not require nor do they prohibit a vehicle from having a front axle limiting valve. Therefore, vehicles need not have these valves in order to meet our standard and you are not prohibited from removing the front axle limiting valve in the design you propose. In fact, an interim technical report of the NHTSA Heavy Duty Vehicle Brake Research Program, published April, 1985, concluded that automatic front axle limiting valves in many vehicles. significantly degrade straight line performance in the empty mode and on wet surfaces. However, if a vehicle does have an automatic pressure limiting valve, it must meet the test requirements set out in S6.1.8.1 of Standard 121. Sincerely, Original Signed by Erika Z. Jones Chief Counsel |
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ID: nht91-4.12OpenDATE: June 3, 1991 FROM: Samuel Albury -- President, Three Wolves and Associates, Inc. TO: Chief Counsel, NHTSA TITLE: None ATTACHMT: Attached to letter dated 7-12-91 from Paul Jackson Rice to Samuel Albury (Signature by Ken Weinstein) TEXT: I am writing to get a rulling on a matter thats in the development stage. My company is now negotiating with a manufacturer of jeep converison kits. We are planning to use the kits to bring about a smarter looking Jeep. One that all age groups will like to own. The structure will be the same configuration as the present jeeps made by the Chrysler corporation. The body will be one solid piece, the wheel wells will be added. The doors, windshield (with the required safety glass) will be added. The top solid (or canvas) all designer series will be added. The roll bar will be dressed-up. We would buy the basic stripped down model jeep from the Chrysler Corp (if Possible) and add the body, stereo, a/c, tires, running lights, carpeting, high visibility seats OR purchase just the chassis with (engine, transmission, etc ) from Chrysler and add the above. We hope to make the first prototype for marketing by end of year. THE ONLY DIFFERENCE BETWEEN THE CHRYSLER JEEP AND WHAT WE PROPOSE IS THE BODY WILL BE VERY BRIGHT, RUST FREE AND A LITTLE HEAVIER. I was told that I might be considered the manufacturer of the jeeps by making the stated changes. Please provide some guidance in this matter. Attachment Photos of the jeep. (graphics omitted) |
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ID: nht95-6.33OpenTYPE: INTERPRETATION-NHTSA DATE: August 31, 1995 FROM: John Womack -- Acting Chief Counsel, NHTSA TO: Yvonne Anderson -- Todd Vans TITLE: NONE ATTACHMT: ATTACHED TO 7/13/95 LETTER FROM YVONNE ANDERSON TO MARY VERSAILLES (OCC 11047) TEXT: Dear Ms. Anderson: This responds to your letter of July 13, 1995, concerning a van which your company is modifying. The van is owned by a local school system. The school system has asked your company to raise the roof, extend the side door, install wheelchair tiedowns, and install a wheelchair lift. The vehicle was certified as a "bus," but your modification would reduce the seating capacity so that the vehicle would become a "multipurpose passenger vehicle" (MPV). You asked whether this vehicle must be certified following the modifications. The answer to your question is no. By way of background information, the National Highway Traffic Safety Administration (NHTSA) is authorized to issue Federal motor vehicle safety standards that apply to the manufacture and sale of new motor vehicles. A vehicle must be certified as complying with all applicable safety standards before it can be sold or imported. After the first retail sale, there is a limit on modifications made to vehicles. Manufacturers, distributors, dealers, and repair businesses are prohibited from "knowingly making inoperative" any device or element of design installed on or in a motor vehicle in compliance with an applicable safety standard (49 USC @ 30122). In general, the "make inoperative" prohibition would require a business which modifies motor vehicles to ensure that they do not remove, disconnect, or degrade the performance of safety equipment installed in compliance with an applicable safety standard. 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. |
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ID: nht95-4.11OpenTYPE: INTERPRETATION-NHTSA DATE: August 31, 1995 FROM: John Womack -- Acting Chief Counsel, NHTSA TO: Yvonne Anderson -- Todd Vans TITLE: NONE ATTACHMT: ATTACHED TO 7/13/95 LETTER FROM YVONNE ANDERSON TO MARY VERSAILLES (OCC 11047) TEXT: Dear Ms. Anderson: This responds to your letter of July 13, 1995, concerning a van which your company is modifying. The van is owned by a local school system. The school system has asked your company to raise the roof, extend the side door, install wheelchair tiedowns, a nd install a wheelchair lift. The vehicle was certified as a "bus," but your modification would reduce the seating capacity so that the vehicle would become a "multipurpose passenger vehicle" (MPV). You asked whether this vehicle must be certified foll owing the modifications. The answer to your question is no. By way of background information, the National Highway Traffic Safety Administration (NHTSA) is authorized to issue Federal motor vehicle safety standards that apply to the manufacture and sale of new motor vehicles. A vehicle must be certified as compl ying with all applicable safety standards before it can be sold or imported. After the first retail sale, there is a limit on modifications made to vehicles. Manufacturers, distributors, dealers, and repair businesses are prohibited from "knowingly making inoperative" any device or element of design installed on or in a motor veh icle in compliance with an applicable safety standard (49 USC @ 30122). In general, the "make inoperative" prohibition would require a business which modifies motor vehicles to ensure that they do not remove, disconnect, or degrade the performance of sa fety equipment installed in compliance with an applicable safety standard. 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. |
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ID: 11047Open Ms. Yvonne Anderson Dear Ms. Anderson: This responds to your letter of July 13, 1995, concerning a van which your company is modifying. The van is owned by a local school system. The school system has asked your company to raise the roof, extend the side door, install wheelchair tiedowns, and install a wheelchair lift. The vehicle was certified as a "bus," but your modification would reduce the seating capacity so that the vehicle would become a "multipurpose passenger vehicle" (MPV). You asked whether this vehicle must be certified following the modifications. The answer to your question is no. By way of background information, the National Highway Traffic Safety Administration (NHTSA) is authorized to issue Federal motor vehicle safety standards that apply to the manufacture and sale of new motor vehicles. A vehicle must be certified as complying with all applicable safety standards before it can be sold or imported. After the first retail sale, there is a limit on modifications made to vehicles. Manufacturers, distributors, dealers, and repair businesses are prohibited from "knowingly making inoperative" any device or element of design installed on or in a motor vehicle in compliance with an applicable safety standard (49 USC '30122). In general, the "make inoperative" prohibition would require a business which modifies motor vehicles to ensure that they do not remove, disconnect, or degrade the performance of safety equipment installed in compliance with an applicable safety standard. 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,
John Womack Acting Chief Counsel ref:VSA d:8/31/95
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1995 |
ID: nht88-4.31OpenTYPE: INTERPRETATION-NHTSA DATE: 12/09/88 EST FROM: ERIKA Z. JONES -- NHTSA CHIEF COUNSEL TO: WILLIAM SHAPIRO -- VOLVO CARS OF NORTH AMERICA TITLE: NONE ATTACHMT: FEDERAL MOTOR VEHICLE SAFETY STANDARD NUMBER 106, BRAKE HOSES-REQUEST FOR INTERPRETATION; DATED 6-7-88, OCC-2154, FROM WILLIAM SHAPIRO TEXT: This responds to your letter concerning the testing of hydraulic brake hose assemblies to the whip resistance requirement (S5.3.3) of Standard No. 106, Brake Hoses. I regret the delay in responding. Your question relates to Table II of Standard No. 106, which specifies the amount of slack that should be introduced when mounting brake hose assemblies on the whip test apparatus. (The amount of the hose indicated as "slack" in Table II is the differen ce between the projected length of the hose assembly (when mounted in the whip test machine) and the free length of the hose while maintained in a straight position.) Slack must be present in the hose when mounted on the whip test machine to enable the p roper "whipping" movement of a brake hose assembly. Without slack, an assembly would probably be incapable of withstanding any rotation of the movable header of the whip test apparatus described in Standard No. 106 without rupturing. Table II specifies the amount of slack for some sizes of assemblies, and not for others. You ask whether a hydraulic brake hose assembly of a size falling in the latter category -- viz., an assembly comprised of a brake hose that is 19 to 24 inches in f ree length, and which is more than one-eighth inch or three millimeters (mm.) in diameter -- "need not be tested to meet or exceed the whip resistance requirement" of the standard. With regard to NHTSA's Standard No. 106 compliance testing, your understanding is correct that Table II does not specify the amount of slack for testing assemblies of the size you describe. Due to the absence of the slack specification, NHTSA does not r equire testing of such assemblies to the whip resistance requirements of the standard. With regard to your certification that the brake hose assemblies you manufacture comply with all applicable requirements of Standard No. 106, you are correct that hydraulic brake hose assemblies of the size you describe are not subject to the whip resist ance requirements. However, the agency urges manufacturers to ensure that these assemblies perform in a safe manner while subject to environmental conditions of vehicle operations which may result in flexing of the brake hose or brake hose assembly. Please contact my office if you have further questions. |
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ID: 14668.ztvOpen Mr. Tommie Matthews Dear Mr. Mathews: This is in reply to your letter of March 31, 1997, to Taylor Vinson of this Office, asking how this agency would classify "a Velo Solex 'pedal assisted' bicycle." As you describe it, the Velo Solex is equipped with a small internal combustion engine. The vehicle can be operated as a bicycle driven solely by muscular power, "by leaving the motor in the 'pulled back' position." If the rider wishes to use the assist, the engine will not start until the vehicle reaches a speed of about 5 mph. If the rider stops pedaling, the vehicle will eventually come to a halt as the power of the engine alone is insufficient to keep the vehicle moving. This agency is authorized by Congress to regulate "motor vehicles". In part, a "motor vehicle" is defined as a vehicle driven by mechanical power (49 U.S.C. 30102(a)(6)). It is evident from your description that the primary driving force of the Velo Solex is muscular power, and that the mechanical power of the engine is not operative at all times the bicycle is in motion and only supplements the primary driving force. We have therefore concluded that the Velo Solex is not a "motor vehicle" subject to the regulation of this agency. The Federal agency that has jurisdiction over bicycles is the Consumer Product Safety Commission. If you have further questions, you may refer them to Taylor Vinson (202-366-5263). Sincerely, |
1997 |
ID: 1985-02.2OpenTYPE: INTERPRETATION-NHTSA DATE: MARCH 20, 1985 FROM: LARRY GIFFORD -- SERVICE REP., YOKOHAMA TIRE CORPORATION TO: WES SPRUNK -- SAF-TEE SIPING & GROOVING INC. TITLE: NONE ATTACHMT: DECEMBER 30, 1988 LETTER FROM JONES TO SPRUNK, OCTOBER 8, 1987 LETTER FROM SPRUNK TO JONES, BROCHURES ON TIRE SIPING, 1978 NSC WINTER TEST REPORT, AUGUST 19, 1986 LETTER FROM KEIL TO SPRUNK, ARTICLE FROM AUGUST 19, 1986 ISSUE OF "SCHOOL BUSINESS AFFAIRS," ARTICLE ENTITLED "SLASHING TIRES FOR SAFETY AND SAVINGS" FROM DECEMBER 1984 "NATIONAL SCHOOL BUS REPORT," OCTOBER 15, 1982 LETTER FROM PALMER TO MARCY MANUFACTURING, AND APRIL 1983 AND APRIL 1984 ARTICLES FROM "GW SAFETY TALK" TEXT: Reference is made to our conversation concerning truck tire siping at the N.W.T.D.A. meeting here in Portland 2/7/85. Several of our dealers, mainly in Montana and Colorado, have been making this service a practice for many years. In doing so, it achieves three main benefits; improved traction, less free roll wear on radials (steer & trailer positions) and extends mileage. I also mentioned going a step further and have had three sets of our logging tires siped at 11/32 depth. The tire is our 710 and originates with 25/32. The results were about 40% less usage of chains; less abrasive damage to tread area and 7-10% more mileage. The tires are not to recap stage, but I do not expect any carcass failures from the siping. I surely recommend this service now in all types of tire usage. |
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ID: nht71-5.1OpenDATE: 11/17/71 FROM: AUTHOR UNAVAILABLE; J. W. Carson for E. T. Driver; NHTSA TO: Ward School Bus Mfg., Inc. TITLE: FMVSS INTERPRETATION TEXT: Your letter of October 28, 1971, to Mr. Stan Haranski, Truck Body and Equipment Association, Inc., concerning switching arrangements for school bus red signal lamps, has been forwarded to this Office for reply. Paragraph S4.1.4(a) of Federal Motor Vehicle Safety Standard No. 108 requires that the four red signal lamps be controlled by a manually actuated switch. A two-way switch, whereby all four lamps are activated when the switch is in one position, and the two rear lamps only are activated when the switch is in the opposite position, would not be in violation of this requirement of Standard No. 108. |
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ID: 2841oOpen The Honorable Terry L. Bruce Dear Mr. Bruce: I have been asked to respond to the letter which you wrote, on behalf of Mid America Design, Inc., to Mr. Daniel C. Holland, the District Director for the United States Customs Service in Seattle, Washington. That company attempted to import a shipment of "spinner hubcaps" from Taiwan. These hubcaps were seized by the U.S. Customs Service for failing to conform with the requirements of Federal Motor Vehicle Safety Standard No. 211, Wheel Nuts, Wheel Discs, and Hubcaps (49 CFR 571.211). In your letter to Mr. Holland, you asked to be furnished with an official statement that "spinner hubcaps" do not comply with Standard No. 211, and asked why these imported "spinner hubcaps" are treated differently from those currently available in this country. I am pleased to have this opportunity to explain our regulations to you. I have enclosed copies of my May 13, 1987 letter to the Honorable William E. Dannemeyer and my November 13, 1987 letter to Mr. William J. Maloney. In these letters, I reaffirmed our interpretations from the past 20 years stating that spinner hub caps do not comply with the requirements of Standard No. 211, and have not complied with that Standard since it became effective on January 1, 1968. Section 108(a)(1)(A) of the National Traffic and Motor Vehicle Safety Act [15 U.S.C. 1397(a)(1)(A)] makes it illegal to "manufacture for sale, sell, offer for sale, or introduce or deliver for introduction in interstate commerce, or import into the United States" any hub caps that do not comply with Standard No. 211 (Emphasis added). Therefore, the U.S. Customs Service was enforcing the law properly when it seized the spinner hubcaps Mid America sought to import. You also stated in your letter that spinner hubcaps are currently available in the United States, and enclosed some advertisements offering spinner hubcaps for sale. I would like to thank you for bringing this matter to our attention. We have referred this information to our enforcement staff for appropriate action. I hope this information is helpful. If you have any further questions or need more information, please do not hesitate to contact me. Sincerely,
Erika Z. Jones Chief Counsel Enclosures ref:211 d:3/16/88 |
1988 |
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.