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: 2414yOpen Ms Margaret Schmock Dear Ms Schmock: This is in reply to your FAX of March 6, l990, with respect to the relationship between Federal Motor Vehicle Safety Standard No. l08, and "CAC Title 13, Article 9". You have indicated that CAC requires a headlamp adjustment range in the horizontal of at least +/- 4 degrees, whereas Standard No. l08 requires a horizontal adjustment range of not less than 2.5 degrees. You have asked whether Bosch headlamps still must have an adjustment range of +/-4 degrees in the horizontal although Standard No. l08 has been changed. We understand that "CAC" refers to "California Administrative Code". The effect of the preemption provisions of the National Traffic and Motor Vehicle Safety Act is to prohibit California from adopting and enforcing a minimum horizontal headlamp adjustment range greater or less than 2.5 degrees. Thus, a State requirement that a headlamp have a horizontal range of +/- 4 degrees is invalid because it differs from a corresponding Federal requirement. We are unable to answer your further questions with respect to the California code, and suggest that, for further information you write Department of Motor Vehicles, State of California, 2415 First Avenue, Sacramento, California 95818, ATTN: Mr. A. A. Pierce, Director (FAX 916-732-7854). Sincerely, Stephen P. Wood Acting Chief Counsel ref:l08 d:4/25/90 |
1990 |
ID: nht93-7.32OpenDATE: October 21, 1993 FROM: James "Bubba" Schaub -- Midas Muffler and Brake TO: John Womack -- Acting Chief Council, NHTSA TITLE: None ATTACHMT: Attached to letter dated 5/8/94 from John Womack to James Schaub (A42; Std. 105; Part 570) TEXT: First allow me to introduce myself. My name is James "Bubba" Schaub. I manage a Midas Muffler and Brake Shop in Slidell, Louisiana, located at 180 Gause Blvd., and have for 9 years now. My concern is in the area of ethical and sound business practice. I'm taught by Midas to replace brake rotors and/or brake drums when they exceed the minimum thickness (on disc rotors) or maximum diameter (on drums), published by Original Equipment Manufacturers. My questions are as follows: 1. Please interpret F.M.V.S.S. 105 HYDRAULIC BRAKE SYSTEMS. 2. Is there any basis for fraud in following this policy? (Of disc rotor and/or drum replacement when out of manf. safety tolerances). Please understand that my concern lies only with doing the right thing - the safe way, for our costumers. Let it be known that the local auto dealership service dept.'s are not following their own recommendations, for safety in this matter, which causes my costumers to believe that we (Midas) are fraudulently selling and installing parts on their vehicles when they're not needed. But, if I can present an established standard to our (Midas) costumers, I can prevent them from feeling they've been taken advantage of. |
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ID: nht75-2.15OpenDATE: 04/21/75 FROM: AUTHOR UNAVAILABLE; J. C. Schultz; NHTSA TO: Dominion Auto Accessories Limited TITLE: FMVSS INTERPRETATION TEXT: This is in response to your letter of March 20, 1975, inquiring as to the permissibility of selling your "Panamirror" in the United States as aftermarket equipment. Motor Vehicle Safety Standard No. 111, Rearview Mirror, provides minimum performance requirements for rearview mirrors on passenger cars and multipurpose passenger vehicles. According to the standard, the inside rearview mirror must furnish the driver with a specified field of view to the rear of substantially unit magnification. Any vehicle manufactured for sale, sold, or introduced into interstate commerce must be equipped with an inside rearview mirror that meets the designated level of performance. It appears that the "Panamirror" would not satisfy the requirements of the provision, because it is convex in structure and therefore would not provide a view of substantially unit magnification. If the mirror were installed on a vehicle as aftermarket equipment (after the vehicle's first purchase for purposes other than resale) in such a way as to render inoperative the inside rearview mirror, section 108(a) (2) (A) of the National Traffic and Motor Vehicle Safety Act (Pub. L. 89-563) as amended (Pub. L. 93-492) would apply where the installation was accomplished by a manufacturer, distributor, dealer, or motor vehicle repair business. The section prohibits the named parties from knowingly rendering inoperative a system installed in compliance with an applicable motor vehicle safety standard. |
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ID: nht75-3.26OpenDATE: 03/04/75 FROM: AUTHOR UNAVAILABLE; James C. Schultz; NHTSA TO: Minnesota Automotive Inc. TITLE: FMVSR INTERPRETATION TEXT: This is in reply to your letter of January 6, 1975, requesting an opinion on whether a person who installs a Mico Brake Lock device on a new vehicle before its sale to the first purchaser is required to affix an alterer label in accordance with 49 CFR @@ 567.7 and 568.8. You state that you believe the device, which serves as a hydraulic parking brake, is readily attachable because it can be installed in a minimum amount of time and does not in any way alter the operation of the vehicle's original brake system. The NHTSA will generally abide by a good faith determination on the part of a manufacturer that a device is readily attachable. Such a decision should be based primarily on the intricacy of the installation of the device. Simple tools, a relatively short installation time, and the ability to install the device without extensively modifying the vehicle would all be factors pointing to a decision that a component is readily attachable. You should note that section 567.7 of the Certification regulations also requires an alterer label when the installation of a component invalidates a vehicle's existing weight ratings, whether or not the component is readily attachable. On the basis of your letter, however, it appears to us that this would not occur as a result of installation of the Mico Brake Lock device. If your device meets these criteria, no additional labeling will be required. |
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ID: nht95-1.31OpenTYPE: INTERPRETATION-NHTSA DATE: January 17, 1995 FROM: Randall B. Clark -- A Concerned Citizen TO: Office of Vehicle Safety Compliance TITLE: None ATTACHMT: ATTACHED TO 2/16/95 LETTER FROM PHILIP R. RECHT TO RANDALL B. CLARK (A43; STD. 108; VSA 30122(6) TEXT: I respectfully request clarification on the following paragraphs S5.1.1.27(a), Table III & Table IV, located in the "Code of Federal Regulations". I contend the required Motor Vehicle Lighting Equipment requirements are the minimum requirements ONLY and do not state that this is the maximum stop lamps allowed on the back of any automobile. In other words, my automobile has the normal two stop lamps and has a spoiler with a stop lamp built into it. The car also has a stop lamp mounted inside the back window which is not currently hooked up due to the fact that "Subaru of America" thinks the procedure is against the law. They have cited the above paragraphs & Tables as their authority. I would appreciate a specific explanation from the "EXPERTS" stating that an automobile with four stop lamps is perfectly legal in the United States. Thank you for your dedicated efforts on my behalf to clarify the correct point of view on Motor Vehicle Lighting Equipment. P. S. I have enclosed the specific paragraphs & Tables discussed in my letter. (ENCLOSURE OMITTED) |
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ID: nht71-3.17OpenDATE: 06/08/71 FROM: L. R. SCHNEIDER -- ACTING CHIEF COUNSEL, NHTSA; SIGNATURE BY DAVID SCHMELTZER TO: British Leyland Motors Inc. TITLE: FMVSR INTERPRETATION TEXT: This is in reply to your letter of May 20, 1970, requesting an interpretation of the Tire Identification and Record Keeping Regulation (49 C.F.R. 574). The proposals you described in your letter, paragraphs 1 and 2, will certainly meet the minimum requirements of the regulation and are perfectly acceptable. The regulation requires that a record be kept of the type of tire shipped on or in the vehicle. It does not require that the individual tire identification number be(Illegible Word) with the name and address of the purchaser. If a vehicle dealer sells a vehicle equipped with tires which were not shipped on or in the vehicle, the vehicle dealer is considered a tire dealer under section 574.9(b) and as such, he is required to record the name and address of the first purchaser along with the tire identification number, and forward this information to the tire manufacturer. However, the tire manufacturer may designate someone else to maintain the required records by section 574.7. Therefore, it would be acceptable to have your vehicle dealers forward the required information to you instead of to the tire manufacturer, if the tire manufacturer designates you to maintain the records of tires installed on your vehicles. If we can be of any further assistance, please feel free to write. |
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ID: nht72-6.16OpenDATE: 12/20/72 FROM: AUTHOR UNAVAILABLE; Lawrence R. Schneider; NHTSA TO: Center for Auto Safety TITLE: FMVSR INTERPRETATION TEXT: Thank you for your letter of 20 November, 1972, concerning alleged non-compliance of the Defect Information Report regarding Volkswagen Windshield Wipers, submitted by Volkswagon of American on October 12, 1972, with the requirements of NHTSA's Defect Reports Regulations, 49 CFR Part 573. We agree that Volkswagen has failed to supply information required by sections 573.4(c)(2) and 573.4(c)(8) of the Regulation, specifically, the months of manufacture of the affected vehicles and a chronology which includes warranty claims, field service bulletins, and other such information. We are contacting Volkswagon to determine why the Company has failed to furnish that information and to attempt to obtain it. We also agree with your conclusion that 100% of 1948-1949 Volkswagens are potentially affected by the windshield wiper defect. However, Volkswagen's statement that 'no information is available" as to either the total number of such vehicles operating in the United States, or the percentage potentially affected satisfies the disclosure requirement of the regulation (49 CFR 573.4(c)(3, 4)). We cannot agree, however, with your remaining assertions of non-compliance with the Regulations. While the Volkswagen Information Report is lacking in detail and is a poor example of an informational communication, it does contain minimal responses to the enumerated requirements of the Regulations. Thank you for your interest in motor vehicle safety. |
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ID: nht91-2.50OpenDATE: March 26, 1991 FROM: Eric G. Hoffman -- Russell & Hoffman Incorporated TO: Harry Thompson -- NHTSA TITLE: Re: NEF 32; National Traffic and Motor Vehicle Safety Act of 1966, 49CFR, Chapter V, Subpart A-571 (the "Act") ATTACHMT: Attached to letter dated 4-29-91 from Paul Jackson Rice to Eric G. Hoffman (A37; Part 571.3) TEXT: This firm represents a private school which operates and/or rents mini-vans which are designed to carry more than 10 passengers. The school has become aware of the Act and is concerned whether the operation of the vans is in compliance with the applicable regulations under the Act. We would appreciate your providing us: (1) guidance as to the continuing effect of this Act; (2) the procedures for obtaining a variance from the regulations of the Act under certain circumstances; (3) the procedures regarding modification of any non-complying vehicles; (4) the federal guidelines for the estimated cost of such modifications; (5) the terms of any grace period for modification of vehicles to bring them into compliance; (6) the applicable administrative entity charged with enforcement of the Act; and (7) any certification process for vehicles having been modified. To the extent any of the above are non-existent, please so advise us. After your review of this letter, I would appreciate your contacting me at your earliest convenience to further discuss this matter. Thank you for your attention and cooperation. |
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ID: nht90-2.25OpenTYPE: INTERPRETATION-NHTSA DATE: APRIL 25, 1990 FROM: STEPHEN P. WOOD -- ACTING CHIEF COUNSEL, NHTSA TO: MARGARET SCHMOCK -- ROBERT BOSCH GMBH TITLE: NONE ATTACHMT: TELEFAX DATED 6-3-90 TO STEPHEN P. WOOD FROM MARGRET SCHMOCK ATTACHED; (OCC 4508) TEXT: This is in reply to your FAX of March 6, 1990, with respect to the relationship between Federal Motor Vehicle Safety Standard No. 108, and "CAC Title 13, Article 9". You have indicated that CAC requires a headlamp adjustment range in the horizontal of at least +/- 4 degrees, whereas Standard No. 108 requires a horizontal adjustment range of not less than 2.5 degrees. You have asked whether Bosch headlamps still must have an adjustment range of +/-4 degrees in the horizontal although Standard No. 108 has been changed. We understand that "CAC" refers to "California Administrative Code". The effect of the preemption provisions of the National Traffic and Motor Vehicle Safety Act is to prohibit California from adopting and enforcing a minimum horizontal headlamp adjustm ent range greater or less than 2.5 degrees. Thus, a State requirement that a headlamp have a horizontal range of +/- 4 degrees is invalid because it differs from a corresponding Federal requirement. We are unable to answer your further questions with respect to the California code, and suggest that, for further information you write Department of Motor Vehicles, State of California, 2415 First Avenue, Sacramento, California 95818, ATTN: Mr. A. A. Pi erce, Director (FAX 916-732-7854). |
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ID: 571.141 NCC-230601-001 Nagaraj-SuperhornOpenSeptember 13, 2023 Dear Mr. Nagaraj, This letter responds to your inquiry to the National Highway Traffic Safety Administration (NHTSA) regarding compliance of a new horn function named “Superhorn” with Federal Motor Vehicle Safety Standard (FMVSS) No. 141. Based on the information you provided, as explained in more detail below, we have concluded that Superhorn is permissible under FMVSS No. 141. Description of the Superhorn You state that Superhorn is a feature that plays a horn sound through the same system used for emitting the pedestrian alert sound; the vehicle would not be equipped with a traditional horn trumpet. In addition to being user-actuated, you state that Superhorn would resemble a traditional horn both in sound and loudness and would only be played for the duration of continuous horn control actuation (up to a maximum of a 60 seconds before the system times out). You further state that Superhorn is independent of the pedestrian alert system, and that the pedestrian alert system would be emitted alongside the Superhorn sound from the same speaker system. You acknowledge that the pedestrian alert sound may be masked to some extent by the horn when the horn is actuated. Background NHTSA established FMVSS No. 141 in 2016, pursuant to the Pedestrian Safety Enhancement Act of 2010 (PSEA).1 The standard sets minimum sound level requirements for hybrid and electric light vehicles operating at low speeds and aims to reduce injuries to pedestrians and other road users by increasing the detectability of hybrid and electric vehicles. NHTSA does not approve motor vehicles or motor vehicle equipment and does not determine whether a product conforms to the FMVSS outside of an agency compliance proceeding. Discussion There are three requirements of FMVSS No. 141 pertinent to the analysis of the Superhorn. Sound performance requirements (S5.1 through S5.4) S5.1 through S5.4 describe performance characteristics related to measured volume and frequency bands of sounds emitted from covered vehicles. The volume and frequency requirements described in S5.1 through S5.4 are vehicle-level requirements; individual sounds such as horns, including the proposed Superhorn, are not required to independently meet those requirements.2 The performance requirements described in S5.1 through S5.4 are intended to measure the detectability of a vehicle during routine operation. Since the Superhorn is not automatically engaged during routine operation, the Superhorn may not be used to meet FMVSS No. 141’s minimum required sound levels.3 Sameness requirement (S5.5) S5.5 describes the “Sameness requirement,” which requires all vehicles of the same make, model and trim equipped with a pedestrian alert sound to emit the same set of sounds. NHTSA has previously explained that the Sameness requirement, which stems from the PSEA,4 only applies to sounds added to the vehicle for the purposes of complying with the standard.5 The agency believes that this interpretation is still appropriate. Requiring all sounds produced by non- pedestrian alert systems to be identical would be overly burdensome and would prevent certain optional equipment that could affect the sound of a vehicle from being offered for sale. Even though the Superhorn would be played through the same speaker system as the pedestrian alert system, according to your description it is not being added to meet volume and frequency requirements of FMVSS No. 141, and it is only active during horn control actuation. Therefore, Superhorn is not subject to the Sameness requirement. Prohibition on altering the sound of a covered vehicle (S8(b)) S8(b) prohibits providing “any mechanism, equipment, process, or device intended to disable, alter, replace, or modify the sound emitting capability of a vehicle subject to this standard, except in connection with a repair of vehicle malfunction or to remedy a defect or non-compliance.” S8(b) is derived from a similar provision in the PSEA.6 In proposing S8(b), NHTSA described the intention of the provision as “to avoid the situation where vehicle sounds are changed, at the request of the consumer, to something individualized and no longer associated with the specific make/model of motor vehicle, or indeed even recognizable as a motor vehicle at all.”7 NHTSA reaffirmed this position in response to a petition for reconsideration, stating that S8 is intended to prevent access to vehicle features that could modify or adjust the emitted sound or render it noncompliant.8 As a practical matter, NHTSA has not applied S8(b) to other vehicle devices or mechanisms such as traditional horns or audio systems, even though these systems have the potential to alter the sound produced by vehicles and how they are perceived by pedestrians. NHTSA views S8(b) as preserving the integrity of the pedestrian alert system and, more generally, the vehicle’s detectability by pedestrians. Devices that directly touch upon the vehicle alert system, including a vehicle’s pedestrian alert speakers or audio file, receive a higher level of scrutiny. This is not to imply, however, that these are the only systems that may potentially run afoul of S8(b); devices or mechanisms that supersede or replace the pedestrian alert sound may also be found non-compliant. NHTSA believes that the Superhorn, as it is described in your correspondence, does not conflict with S8(b). From your description, the pedestrian alert would continue to play the same set of sounds unaltered and concurrent with the Superhorn for the duration of horn control actuation. As you noted, the Superhorn has the potential to mask the pedestrian alert, in much the same way as a traditional horn may mask a pedestrian alert. However, the pedestrian alert would be masked with a trumpet sound resembling the tone, pitch, and loudness of a traditional car horn and only while the Superhorn sounds. Trumpet horn sounds are distinctive and recognized as a warning to pedestrians and other road users of an imminent hazard such as a vehicle collision. NHTSA notes that this interpretation is based on the description of the Superhorn you provided. If the Superhorn’s performance varies in any way materially from the description you provided, this interpretation will no longer be applicable. For example, if the Superhorn played in the absence of continuous horn control actuation, played for a longer duration, played a sound that made vehicles less identifiable as a vehicle, or disabled the pedestrian alert sound, then the feature would likely be deemed a device that alters, disables, or replaces the pedestrian alert in contravention of S8(b) or a pedestrian alert subject to the Sameness requirement in S5.5. I hope this information is helpful. If you have any further questions, please feel free to contact Paul Connet of my staff at this address or at (202) 366-5547.
Sincerely,
John Donaldson
1 Pub. L. No. 111-373, 141 Stat. 4086 (Jan. 4, 2011). 2 Hybrid and electric vehicles are not required to have a dedicated pedestrian alert sound; vehicles that produce sufficient sound to meet the performance requirements described by S5.1-S5.4 may satisfy the requirements of FMVSS no. 141 without a dedicated alert system. See 81 FR 90416, 90450 (Dec. 14, 2016). 6 See PSEA § 3(2).
Dated: 9/13/23 Ref: Standard No. 141 |
2023 |
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.