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NHTSA's Interpretation Files Search
NHTSA's Chief Counsel interprets the statutes that the agency administers and the regulations that it promulgates. When members of the public ask the agency a question about motor vehicles or motor vehicle equipment that involves these statutes and regulations, the Chief Counsel responds with a letter of interpretation that looks at the particular facts presented in the question and explains how the law applies given those facts. These letters of interpretation, signed by the Chief Counsel, 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 represent the opinion of the agency on the questions addressed at the time of signature and may be helpful in determining how the agency might answer a question that you have if that question is similar to a previously-considered question. Please remember, however, that interpretation letters represent the opinion of the Chief Counsel based on the facts of individual cases at the time the letter was written. Do not assume that a prior interpretation will necessarily apply to your situation! There are a number of reasons why the interpretation letters in this database might not be applicable to your situation. For more information, see the item below, "How do I use letters of interpretation?"

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Results: 16534
571.205--Plexiglass Barriers Clarification--Klos
Dear Mr. Klos:   This responds to your email to the National Highway Traffic Safety Administration (NHTSA) asking about a letter of interpretation NHTSA issued to Mr. Mike Collingwood of the Illinois DOT on August 11, 2020. The letter concerned the installation of plexiglass barriers installed to the right of the driver in school buses to help minimize the spread of the Coronavirus Disease 2019 (COVID-19). Please note that our answer below is based on our understanding of the specific information provided in your email.   Background   NHTSA is authorized by the National Traffic and Motor Vehicle Safety Act ... May 31, 2022

NCC-210420-001--Retention Requirement 304 (001)
Dear Mr. Willard: This responds to your request for an interpretation of how S5.2 of Federal Motor Vehicle Safety Standard (FMVSS) No. 305, Electric-powered vehicles: electrolyte spillage and electrical shock protection, would apply to low-mass, small-energy, high voltage electric vehicle (EV) components that store small amounts of electricity, such as small individual capacitors.1 Specifically, you ask whether these components are ?electric energy storage/conversion devices? that are subject to S5.2, Electric energy storage/conversion device retention.   As explained below, our answer is no. Given that the purpose of S5.2 is to protect vehicle occupants from injury by heavy projectiles in a ... May 31, 2022

571.108--HELP System--Powers
Dear Mr. Powers:   This letter responds to your request for an interpretation of whether your company?s product, the Hazard Enhanced Lighting Package (HELP) system, would be permitted under Federal Motor Vehicle Safety Standard (FMVSS) No. 108, Lamps, reflective devices, and associated equipment.  As explained below, our answer is yes, but only if the product is automatically activated following a crash that disabled the vehicle on which it is installed, or if manual activation of the system is restricted to when the vehicle is not moving and the parking brake is engaged.   By way of background, the National Highway ... Jan 19, 2021

Legality of Odometer Mileage Blocking Devices--Ro
Dear Mr. Ro:   On January 4, 2021, you sent a letter on behalf of Toyota Motor North America, Inc. (Toyota) requesting the views of the National Highway Traffic Safety Administration (NHTSA) on the legality of devices which connect to the instrument panel in a vehicle to prevent or partially prevent odometers in motor vehicles from accumulating mileage. Your letter indicates that such devices are available for purchase on the Internet and that Toyota believes they may be used to slow or stop the accumulation of mileage shown on the odometer of leased vehicles. Your letter also raises Toyota?s concern ... Jan 12, 2021

571.226--Conversion of vans--M Johnson
Dear Mr. Johnson: This responds to your email forwarded to us by U.S. Senator John Thune?s office, and to your September 4 and September 12, 2020 telephone conversations with Deirdre Fujita of my staff, asking whether a motor vehicle dealer may make certain modifications to your used 2019 passenger vans to convert them to cargo vans. You explain that the work would involve, among other things, removing all passenger seats, seat brackets, and seat belts rearward of the driver?s seat, installing a full partition behind the driver?s seat and right front passenger seat to separate a cargo area, and replacing ... Oct 23, 2020

571.125 -- Warning Devices - Anderson
Dear Ms. Anderson:   Thank you for your letter dated March 9, 2020, following up our February 26, 2020, Compliance Assistance Program (CAP) response about a type of warning device you are interested in producing.   You ask whether there are any Federal regulations regarding the size or reflective coloring for distress signals that may be used in the case of a vehicle emergency. In our original CAP response, we noted that the National Highway Traffic Safety Administration (NHTSA) has issued Federal Motor Vehicle Safety Standard (FMVSS) No. 125, ?Warning devices,? which covers warning devices ?that are designed to be ... Oct 2, 2020

571.205 Plexiglass Barriers (002)
Dear Mr. Collingwood:   This responds to your two inquiries to the National Highway Traffic Safety Administration (NHTSA) about the installation of barriers in school buses to minimize the spread of the Coronavirus Disease 2019 (COVID-19). In your June 16, 2020 email, you ask about the installation of ?plexiglass barriers? installed to the right of, and behind, the driver?s seating position. In a later email, you ask about the installation of clear plastic ?soft shields? that would be installed to the immediate right of and behind the driver, and/or installed throughout the passenger compartment by attachment to the interior roof ... Aug 11, 2020

571.108 -- Parking Lamp Activation -- Mazda 1-- 17-0655.docx_sig (003)
Dear Mr. Robertson, This responds to your letter requesting an interpretation of the ?steady burning? requirement for parking lamps under Federal Motor Vehicle Safety Standard (FMVSS) No. 108, Lamps, Reflective Devices, and Associated Equipment. You ask how the steady burning requirement for parking lamps applies to an optically combined LED parking/turn signal lamp while the turn signal is activated.1 You describe in your letter an optically combined LED parking/turn signal lamp which contains two discrete LED light sources: one that is amber and one that is white. When the LED lamp operates as a parking lamp only, the amber LED ... Jun 11, 2020

571-205-Driver Shield for Buses and Vans_final signed (002)
Dear Ms. Sparks: This responds to your May 7, 2020 email asking about adding ?driver shields? to transit buses and vans. You explain that you are developing a driver?s shield assembly to provide to your customers in the transit industry in an effort to protect drivers from the Coronavirus Disease 2019 (COVID-19). You describe the shields as being constructed with plexiglass, stainless tubing and fasteners, with a swing out door to give drivers access to the stepwell entry platform and passenger cabin. You ask about the requirements that would apply when adding these shields to vehicles. We appreciate this opportunity ... Jun 4, 2020

571.208--Center seat--Glickenhaus--19-1007
Dear Mr. Glickenhaus: This responds to your March 25, 2019 request for interpretation asking how the requirements of Federal Motor Vehicle Safety Standard (FMVSS) No. 208; Occupant crash protection, apply to a passenger car and multipurpose passenger vehicle (MPV) with centrally located front seating positions.  Specifically, you ask us to confirm that FMVSS No. 208 does not require air bags for the central front seat(s) if they are not ?outboard designated seating positions? as defined in 49 CFR § 571.3(b).  As we explain below, based on the information and representations provided in your request, FMVSS No. 208 does not require ... Dec 30, 2019

571.108 -- AMA -- Schaye--front color changing light
Dear Mr. Schaye: This responds to your letter requesting an interpretation of whether your auxiliary lamp, the Auto Motion Alert (?your product?), is permissible under Federal Motor Vehicle Safety Standard (FMVSS) No. 108, Lamps, reflective devices, and associated equipment.  Because your product would be installed as aftermarket equipment, not as original equipment, and would not replace original equipment, and because FMVSS No. 108 applies only to equipment installed as original equipment or that replaces original equipment, we have interpreted your request as asking whether the installation of your product is permissible under the ?make inoperative? provision of the National Traffic ... Sep 9, 2019

19-000881- 30122 -- Hestrin interp request_v3
Dear Mr. Hestrin,   This responds to your March 5, 2019 letter to the National Highway Traffic Safety Administration (NHTSA) regarding an aerodynamic device to improve the aerodynamic efficiency of heavy vehicles.  We have interpreted your letter as asking whether such a product would be in compliance with NHTSA regulations.   Applicable Requirements   The National Traffic and Motor Vehicle Safety Act (Safety Act; 49 U.S.C. Chapter 301) authorizes NHTSA to issue Federal motor vehicle safety standards (FMVSSs) applicable to new motor vehicles and new items of motor vehicle equipment.    NHTSA does not provide approvals of motor vehicles or ... Aug 27, 2019

571.226--modified roof--Summit Bodyworks
Dear Mr. Arnett:   This responds to your inquiry asking whether your vehicles are ?modified roof vehicles,? a type of vehicle that is excluded from the applicability of Federal Motor Vehicle Safety Standard (FMVSS) No. 226, ?Ejection mitigation.?  As explained below, our answer is yes.    Paragraph S2 of FMVSS No. 226 excludes ?modified roof vehicles? from the standard.  The term ?modified roof? is defined in S3 of FMVSS No. 226 as follows: ??Modified roof? means the replacement roof on a motor vehicle whose original roof has been removed, in part or in total, or a roof that has to be ... Aug 27, 2019

571.209--Attachment hardware--Freedman--17-0328
Dear Mr. Klopp:   This responds to your request for an interpretation concerning the attachment hardware requirements in Federal Motor Vehicle Safety Standard (FMVSS) No. 209, Seat belt assemblies.  You ask whether it is acceptable to use attachment hardware smaller than that specified in the standard if the seating system complies with the strength requirements of FMVSS No. 210, Seat belt assembly anchorages.  As we explain below, under FMVSS No. 209 it is acceptable to provide attachment hardware other than the 7/16-20 UNF-2A or 1/2-13 UNC-2A attachment bolts specified in the standard if it meets 209?s S4.3(c) strength requirements [FD(1] when ... Aug 12, 2019

571.108--Supplement beam--Boykin--16-0884
Dear Mr. Boykin:   This responds to your letter asking about the application of Federal Motor Vehicle Safety Standard (FMVSS) No. 108, ?Lamps, reflective devices, and associated equipment,? to a lighting system your company has developed.  In your letter and phone conversation with John Piazza of my staff, you describe your product as ?an auxiliary vehicle lamp operating system? for use both as original equipment (OE) and as aftermarket equipment.   You state that your product, which adapts to the existing headlight wiring harness, provides a supplemental lower beam from the existing upper beam when the lower beam fails.  We ... May 17, 2019

571.108 -- HDC Supplemental Turning Lamps -- HAAS -- 15-4155
Dear Mr. Haas:   This responds to your letter asking whether your product, the HAAS Design Concepts sequential perimeter lighting system, is permissible under Federal Motor Vehicle Safety Standard (FMVSS) No. 108, Lamps, Reflective Devices, and Associated Equipment (49 CFR § 571.108).  As explained below, your product is permissible if it operates in a manner that is synchronized with the vehicle?s required turn signals and satisfies the other criteria cited in this letter. By way of background, the National Highway Traffic Safety Administration (NHTSA) is authorized under the National Traffic and Motor Vehicle Safety Act (49 U.S.C. Chapter 301) to ... May 6, 2019

571.111 -- Camera Obstruction -- Keller -- 18-0661
Dear Mr. Keller: This responds to your inquiry on behalf of Bruno Independent Living Aids, Inc., concerning the rear backup camera requirement (S6.2) of Federal Motor Vehicle Safety Standard (FMVSS)   No. 111, ?Rear visibility.?  We apologize for the delay in responding.  You ask several questions on whether installation of the ?Bruno ASL-700 Chariot? and ?ALS-250 Outsider? by vehicle owners would be permitted under the National Traffic and Motor Vehicle Safety Act.  As explained below, our answer is yes.     In your letter, you state that the two products are ?vehicle exterior-located platform lifts which can be temporarily attached to the ... May 3, 2019

dec 11 571.213--Aftermarket built in CRS--Lt. Douglas
Dear Lt. Douglas:   This responds to your September 5, 2017 letter to the National Highway Traffic Safety Administration (NHTSA) and to your December 5 telephone conversation with Deirdre Fujita of my staff, regarding a product called a ?Little Passenger Seat? made by a company called Little Passenger Seats (LPS).  You are concerned about the safety of the product and ask whether it meets Federal Motor Vehicle Safety Standard (FMVSS) No. 213, Child Restraint Systems.   While answering your letter, on December 18, 2017, our staff read on what had been LPS?s website that LPS was ?closing up shop as ... Feb 12, 2018

571-217-Rear Door Emergency Exit-Emad Louis--SPW
Dear Mr. Louis:   This responds to your September 27, 2017 email asking about Federal Motor Vehicle Safety Standard (FMVSS) No. 217, Bus emergency exits and window retention and release.  As we understand your email, you are asking whether the standard allows a certain design configuration on a bus that is over 10,000 pounds and not a school bus.   In your email, you explain that the bus you purchased has a cargo net that can be pulled and secured across a portion of the back of the bus to allow the back of the bus to be used for ... Dec 7, 2017

571.209 -- Inflatable Seat Belt Assembly -- Autoliv -- 16-003634 -- 05.22.2017
Dear Mr. Prentkowski:   This responds to your letter concerning the application of Federal Motor Vehicle Safety Standard (FMVSS) No. 209, Seat Belt Assemblies, to an inflatable seat belt assembly your company is developing.  You ask which strength test applies to a ?structural sew pattern? that connects the assembly?s conventional webbing to its inflatable portion.  Specifically, you ask us to confirm your tentative conclusion that the sew pattern is subject to the assembly performance requirements contained in S4.4(b)(2).  As explained below, S4.4(b)(2) applies to the sew pattern, but it is not the only applicable strength requirement.  The sew pattern, along ... May 22, 2017

574- TIN spacing - Kumho - 16-004483
Dear Mr. Ainbinder:   This letter responds to your request on behalf of Kumho Tire U.S.A., Inc. (Kumho) requesting clarification regarding the spacing requirement for the 13-symbol tire identification number (TIN) required by the National Highway Traffic Safety Administration (NHTSA).  NHTSA published a final rule in the Federal Register on April 13, 2015 (80 FR 19553) requiring all new plants (and, within 10 years, all existing tire plants) to mark tires with a 13-symbol TIN.  You request clarification whether there must be spacing between the three groupings of symbols within the TIN, as shown in figures accompanying 49 CFR 574.5.  ... Feb 27, 2017

15-004254 WayRay Glazing_sb_3
Dear Mr. Monnier:   This responds to your August 12, 2015 letter asking whether your product complies with Federal Motor Vehicle Safety Standards (FMVSSs) and FMVSS No. 205 in particular.   Your letter describes your product as a ?holographic car navigation? system that projects ?navigation information? on ?a transparent film in the windshields.?  Based on your description, we assume that your product might be installed on a new motor vehicle or as an aftermarket item.   By way of background, the National Highway Traffic Safety Administration (NHTSA) is authorized by the National Traffic and Motor Vehicle Safety Act (?Safety Act,? ... Jan 19, 2017

16-2706 (GM load limiters on buses Aug 8)_v2 incorporating circulation comments
Dear Mr. Latouf:   This letter responds to a letter from M. Carmen Benavides, dated March 7, 2013, requesting an interpretation of Federal Motor Vehicle Safety Standard (FMVSS) No. 209, ?Seat belt assemblies.?  We unfortunately did not receive the letter until it was subsequently emailed to us by your staff on May 24, 2016.               GM asks about section S4.5(b) of FMVSS No. 209 as applied to twelve- and fifteen-passenger buses with a gross vehicle weight rating (GVWR) greater than 8,500 pounds (lb) and less than or equal to 10,000 lb (?subject buses?).  GM indicates that it is considering ... Jan 19, 2017

571-209-fire truck seat belt assemblies-Christopher Palabrica-16-000817
Dear Mr. Palabrica:   This responds to your email requesting an interpretation regarding Federal Motor Vehicle Safety Standard (FMVSS) Nos. 209, Seat belt assemblies, and 210, Seat belt assembly anchorages.  You state that you refurbish fire trucks and, as part of the process, would like to replace the existing Type 2 seat belt assemblies with new Type 2 seat belt assemblies that include ?seat belt monitoring systems.?[1]  You ask whether you may install the new seat belt assemblies in the refurbished fire trucks.   In your email it was unclear how extensively you refurbish the fire trucks.  In a telephone ... Jan 19, 2017

16-005785 FAMA Interp
Dear Ms. Glassman:   This responds to your April 1, 2015 letter on behalf of the Fire Apparatus Manufacturer?s Association (?FAMA?) requesting guidance as to whether work equipment installed on a fire truck that is inoperative during travel, and only operative once the fire truck reaches a work site, is ?motor vehicle equipment? under the National Traffic and Motor Vehicle Safety Act (the ?Safety Act?) and therefore subject to the Safety Act?s recall notification and remedy provisions.  As part of this request, you specifically ask NHTSA to confirm your view that, provided work equipment meets certain conditions and does not ... Jan 4, 2017