ID: nht90-1.90

TYPE: INTERPRETATION-NHTSA

DATE: 03/29/90

FROM: JIM LEUSNER -- ORLANDO SENTINEL

TITLE: U.S. SUES CAR-WINDOW TINTERS -- LET THERE BE MORE LIGHT

ATTACHMT: ATTACHED TO LETTER DATED 06/25/90, FROM PAUL JACKSON RICE -- NHTSA TO LAWRENCE J. SMITH -- CONGRESS; A35; VSA 108 [A] [2] [A]; STANDARD 205; LETTER DATED 05/30/90 FROM NANCY L. BRUCE -- DOT TO LAWRENCE J. SMITH -- CONGRESS; LETTER DATED 05/25/9 0 FROM LAWRENCE J. SMITH -- CONGRESS TO NANCY BRUCE -- DOT; NEWSPAPER ARTICLE; UNDATED BY UPI; US SUES 4 AUTO TINTING SHOPS; OCC 4842; NEWSPAPER ARTICLE DATED 03/30/90; BY STEVE MOORE -- BUSINESS MARKETS; LOCAL CRAFTSMAN UNSWAYED BY FEDERAL CIVIL LAWSUIT S; NEWSPAPER ARTICLE DATED 03/29/90 BY BRUCE VIELMETTI -- ST PETERSBURG TIMES; US CRACKS DOWN ON WINDOW TINTERS; 1984 FLORIDA AUTO TINT LAW; PRESS RELEASE DATED 03/28/90 BY UNITED STATES ATTORNEY MIDDLE DISTRICT OF FLORIDA.

TEXT: In the automobile-window tinting business, the government says the law is black and white. The defendants say it's not so clear.

The Justice Department sued six Florida companies Wednesday for violating federal safety standards. It says the companies, including two in Central Florida are selling and installing tinting film that is too dark and unsafe for motorists.

But some window tinters say it's the federal government that has kept them in the dark.

They say they've been following Florida law that requires film to let at least 35 percent of the light pass through driver and front seat windows of cars, 1 and 20 percent through rear and back-seat windows.

The company owners say they were unaware they were violating a federal law that requires automobile tint to let through at least 70 percent of the light

David Spearin, operator of Shakespearin Inc. of Holly Hill, said he was shocked when told he was a defendant in the suit. He said he was unaware of the differences in the federal and state laws until told by a reporter Wednesday

"We've never been asked to cease and desist," said Spearin, operator of five car stereo and window tinting stores in Central Florida. "We've never been informed there was any problem. This is amazing.

We are complying with the [Illegible Word] in Florida. If the federal standards are different than the state standards, then they should get together."

Blue Skies Protects, Inc., of Orlando, which operates as Flying Window. Tinters at [Illegible Word]. Semoran Blvd also was named in one of the suits.

"This is total insanity," said Suzanne Turner owner of Blue Skies, "I really feel picked on. I haven't done anything bad." Officials of the National Highway Traffic Safety Administration in Washington and the U.S. attorneys office in Tampa could not be reached for comment Wednesday.

Turner and Spearin said they have lost business because they have refused to install film that is darker than allowed by state law. They argue they are legitmate window-tinting firms, compared with other operations that are willing to break the law t o make a buck.

Turner said she received an inquiry from the National Highway Traffic Safety Administration a few years ago asking about tinting products and records. She and her husband packed up their records and flew to Washington to investigate the query, but th e agency representative they met with was "incredibly vague," she said.

Her husband, Tom Turner, who operates a Longwood window-tinting company, said federal transportation officials told the couple the Florida guidelines were considered substandard under federal law. He said he informed the manufacturers of the film, wh o are fighting the government standards.

"They should go after the window-tint manufacturers," Spearin said. "They're the ones selling it. We're just the installers."

A spokesman for Martin Energy Products in Fort Lauderdale, makers of car window tint film with more than 300 customers in Florida, said the tinting industry is trying to get uniform legislation passed that would mirror Florida's standards.

"We are before Congress right now trying to make federal standards a 35 percent law," said company spokesman Glenn Hale.

Hale, Spearin and the Turners say that window tint is not the hazard the government says it is. The tint placed on passenger windows of cars prevents glass from shattering in an accident, they say.

Florida Highway Patrol Lt. Randy Harper in Orlando said troopers often write tickets for motorists who have dark windshield film that violates Florida law. Car owners who tint their rear windows are required to install mirrors on both sides of the veh icle, he said. Those who illegally install film darker than allowed by law face up to 60 days in jail and $ 500 in fines.

Harper said dark tinting has contributed to many night accidents investigated by his agency and has prevented motorists from being able to observe the actions of other drivers helpful for defensive driving.

"It's also a problem in law enforcement walking up to a car and not being able to see what is inside," Harper said.

They should go after the window-tint manufacturers. They're the ones selling it. We're just the installers.

-- David Spearin,

Shakespearin Inc.

ID: 77-3.36

TYPE: INTERPRETATION-NHTSA

DATE: 07/29/77

FROM: AUTHOR UNAVAILABLE; J. J. Levin, Jr.; NHTSA

TO: Cox Trailers, Inc.

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of July 7, 1977, informing us of your wish to relocate combination stop, tail, turn signal and side marker lamps "to the upper rear fender" of the boat trailers that you manufacture. You have asked whether this location complies with the requirements of Standard No. 108.

I am sorry that we cannot give you the interpretation you seek. Standard No. 108 requires that rear side marker lamps be mounted "as far to the rear as practicable," and stop, tail, and turn signal lamps must be mounted "on the rear." Even though, in your opinion, at your planned fender location "the lights will pass all of the required photometric and visibility requirements", when the trailer is carrying a boat the lamps are more likely to be visible "on the rear," as the standard requires.

SINCERELY,

July 7, 1977

Chief Counsel National Highway Traffic Safety Administration U.S. Department of Transportation

With reference to Motor Vehicle Standard 108, we intend to relocate some of the combination stop, tail, turn and side marker lamps to the upper rear fender of our boat trailers. At this location the lights will pass all of the required photometric and visibility requirements.

We need from you an interpretation of the statement that "these lights must be mounted on the rear of the trailer". Could we use this mounting as long as these lights meet the other requirements and can be considered mounted as far to the rear as practicable. The distance from the rear would normally not exceed four (4) feet.

Our reasons for deviating from the rear most position on the trailer is due to trailer construction which makes rear mounting highly impractical.

Your prompt attention to this matter will be greatly appreciated.

COX TRAILERS, INC

William F. Cox President

ID: nht70-2.47

DATE: 10/19/70

FROM: L. R. Schneider, NHTSA

TO: American Honda Motor Company, Inc.

TITLE: FMVSS INTERPRETATION

TEXT: Douglas W. Toms has asked me to reply to your letter of September 8 which requests confirmation "that a transmission gear ratio other than the highest ratio is not required to be available at all speeds below 25 miles per hour".

We cannot confirm this interpretation of S3.1.2 of Motor Vehicle Safety Standard No. 102 (Transmission Shift Lever Sequence, Starter Interlock, and Transmission Braking Effect). The phrase "at vehicle speeds below 25 miles per hour" in that section is inclusive; it means at all speeds below 25 miles per hour, and not at a speed.

Douglas W. Toms Director National Highway Safety Bureau

We would appreciate receiving an interpretation to clarify the meaning of Paragraph S3.1.2 of Federal Motor Vehicle Safety Standard 102.

It is our understanding that a transmission gear ratio other than the highest ratio is not required to be available at all speeds below 25 miles per hour. For example, in the case of a vehicle equipped with a three speed automatic transmission, if second gear became available only when selected at speeds below 15 miles per hour, the vehicle would conform to the requirements of Paragraph S3.1.2 provided that within the speed range when second gear was available, the vehicle deceleration was greater than if the highest gear ratio were engaged.

We believe that rewording Paragraph S3.1.2 of M.V.S.S. 102 as follows would clarify this matter:

"S3.1.2 Transmission Braking Effect. In vehicles having more than one forward transmission gear ratio, one forward drive position shall provide a greater degree of vehicle deceleration than the highest speed transmission ratio when tested below 25 miles per hour and within the speed range at which the lower gear ratio is available."

We would greatly appreciate an early reply.

C. L. Hale Staff Engineer

ID: nht68-3.7

DATE: 08/09/68

FROM: AUTHOR UNAVAILABLE; Robert Brenner; NHTSA

TO: University of Nottingham

TITLE: FMVSR INTERPRETATION

TEXT: On April 17 you wrote Senator Harris for assistance regarding importation of what you described in your "hand-built race car", and asked whether the[Illegible Word] small manufacturer exemption would be applicable to it. I explained in my response to the Senator on May 27 that racing vehicles designed for competition circuits were exempt from the Act, and that a racing vehicle not designed solely for competition might nevertheless be admitted to the United States if imported solely for purposes of competition and not licensed for use on the public roads.

Judging from your letter the "hand-built race car" appeared excepted from the Act and regulations/and it did not seem appropriate to discuss PL 90-283, the small manufacturer amendment.

PL 90-283 authorizes the Secretary of Transportation to exempt temporarily a manufacturer of 500 or less motor vehicles per year from compliance with Federal motor vehicles safety standards after making certain specified findings. Exemptions under the law cannot be given to individual owners.

Procedures were established by which interested manufacturers could apply for an interia temporary exemption pending adoption of final procedures. Although Mr. P.H.G. Morgan had made no recent, a copy of the interim procedures was forwarded to him. In response, Mr. Morgan informed us that he could not submit an application but intended to bring his vehicles into full compliance with all Federal standards, hopefully around the first of 1969.

This means that any Morgan manufactured after December 31, 1967 may not be imported into the United States unless it bears the certification of its manufacturer that it conforms to all Federal standards or unless it comes within one of the exceptions net form on Form HS-7, a copy of which I note you have.

I regret the delay in answering your letter, especially since you state the car is being hand built to your specifications. However, Mr. Morgan has been aware continually of his rights and obligations under the National Traffic and Motor Vehicle Safety Act of 1966 and he may have already explained his position to you.

ID: nht93-7.43

DATE: October 28, 1993

FROM: Jelly, Rachel -- Executive Engineer, Legislation and Certification., Lotus Cars Ltd.

TO: Womak, John -- Acting Chief Council, NHTSA

TITLE: NONE

ATTACHMT: Attached To A Letter Dated 5/9/94 From John Womack To John Bloomfield (A42; PART 525)

TEXT: Lotus / Bugatti, request for clarification regarding CAFE petition(s) for alternative CAFE standards.

Since January 1986 General Motors has owned 100% of Group Lotus. Under GM ownership the fuel economy data from the Lotus vehicles has been included with the GM import fleet for the purposes of CAFE fines and reporting. As GM had enough fuel efficient vehicles in its import fleet to offset the shortfall of the Lotus vehicles fuel economy-performance, no fines were required and thus no waiver petition for an alternative CAFE value was necessary.

On the 27th August 1993 General Motors sold 100% of Group Lotus Ltd to Bugatti International. Bugatti is also a vehicle manufacturer and plans to market passenger cars in the USA commencing with the 1994 model year. Both companies actual/projected sales volumes when taken individually, and combined, will make the companies eligible for classification as a small volume manufacturer. Please see the supporting data on page 3 of this letter for sales projections and fuel economy information.

Lotus now finds itself in the position where it needs to apply for an alternative CAFE standard for the 1994 thru 1997 (and possibly subsequent) model years. Also Bugatti is planning to submit a petition for alternative standards in the near future.

Please could you officially advise me if Lotus will be permitted to petition for its own CAFE value for its vehicles and Bugatti will be able to petition for another value for its fleet, or will Lotus and Bugatti have to combine sales projections and fuel economy data and petition for a joint value? The two manufacturing companies are run as separate entities within the group to maintain the individual identity of the products.

If you require any further information please do not hesitate to contact me, my direct line telephone and fax numbers are 44 953 608131 (tel) and 44 953 608132 (fax).

CONFIDENTIAL.

Lotus and Bugatti US manufacturing and fuel economy data:-

ID: 24229mass

John K. Stipancich
Vice President
Evenflo Company, Inc.
707 Crossroads Court
Vandalia, OH 45377

Dear Mr. Stipancich:

This responds to your letter to the National Highway Traffic Safety Administration (NHTSA) asking about S5.4.3.2 of Federal Motor Vehicle Safety Standard No. 213, "Child Restraint Systems" (49 CFR 571.213). I regret the delay in responding.

You ask whether S5.4.3.2 of Standard No. 213 applies to belt-positioning seats. You believe it does, but have observed that some of your competitors have produced belt-positioning seats that do not appear to comply with that section.

Section S5.4.3.2 states, in pertinent part:

S5.4.3.2 Direct restraint. Except for a child restraint system whose mass is less than 4.4 kg, . . . each Type I and lap portion of a Type II vehicle belt that is used to attach the system to the vehicle shall, when [dynamically] tested in accordance with S6.1, impose no loads on the child that result from the mass of the system . . .

The agency has decided that it will not enforce the requirements of S5.4.3.2 against belt-positioning seats that have a mass greater than 4.4 kg until further notice. While the agency believes that the mass of the seats should be limited so as not to subject the child occupant to excessive loading in a crash, the agency has concerns about the enforceability of the provision against manufacturers of belt-positioning seats that have a mass greater than 4.4 kg. Accordingly, the agency will not apply the provision to belt-positioning seats until further notice.

Sincerely,

Jacqueline Glassman
Chief Counsel

ref:213
d.4/11/03

ID: NCC-230607-001 571.108 Automatic Activation of Hazard Warning Signal for Nonresponsive Driver Frooshani signed 7.22.25

U.S. Department of Transportation
National Highway Traffic Safety Administration
Office of the Chief Counsel
1200 New Jersey Avenue SE. Washington, DC 20590

July 22, 2025

Mr. John Frooshani 

Vehicle Regulatory Manager, Government Relations  

North American Subaru, Inc. 

One Subaru Drive Camden NJ 08103 

Dear Mr. Frooshani,

I write in response to your letter dated February 5, 2020, requesting an interpretation on whether identified advanced driver assistance system (ADAS) features would comply with the hazard warning signal requirements in Federal Motor Vehicle Safety Standard (FMVSS) No. 108; Lamps, reflective devices, and associated equipment. You also spoke with staff from the National Highway Traffic and Safety Administration's (NHTSA) Office of the Chief Counsel on October 29, 2024. You ask whether your system, after determining a driver is non-responsive, could automatically activate the vehicular hazard warning signal while decelerating the vehicle and bringing it to a stop. Our conclusion is that such a system is permissible in the circumstances described in your letter. 

The contents of this interpretation letter do not have the force and effect of law and are not meant to bind the public in any way. This letter is only intended to provide clarity regarding existing requirements under the law at the time of signature. 

Background 

NHTSA is authorized by the National Traffic and Motor Vehicle Safety Act (Safety Act, 49 U.S.C. Chapter 301) to issue FMVSS setting performance requirements for new motor vehicles and new items of motor vehicle equipment. NHTSA does not pre-approve new motor vehicles, new motor vehicle equipment, or new motor vehicle technologies. In addition, NHTSA does not prohibit the introduction of new motor vehicles or motor vehicle technologies such as Automated Driving Systems (ADS) into the vehicle fleet, provided those vehicles and technologies meet applicable FMVSS and do not present a safety defect. The Safety Act requires manufacturers to self-certify that their vehicles and equipment conform to all applicable FMVSS in effect on the date of manufacture. 

Two provisions of FMVSS No. 108 bear on the issue raised in your letter. First, the standard requires vehicles, except trailers and motorcycles, to be equipped with a vehicular hazard warning signal operating unit and a vehicular hazard warning signal flasher.1 A vehicular hazard warning signal operating unit is defined as a driver-controlled device which causes all required tum signal lamps to flash simultaneously to indicate to approaching drivers the presence of a vehicular hazard.2,3 Second, FMVSS No. 108 S6.2.1 states that no additional lamp, reflective device, or other motor vehicle equipment is permitted to be installed that impairs the effectiveness of lighting equipment required by FMVSS No. 108.4 

Your letter states that Subaru is exploring deploying an ADAS with a feature intended to prevent a crash if a human driver has become nonresponsive, with the system assuming vehicular control when a driver is inattentive and non-responsive to system warnings. In the described scenario, the vehicle would be brought to a stop and would "activate the hazard warning lamps as the vehicle is decelerating and continue to activate the hazard lamps after the vehicle has been brought to a stop." You state that, in your opinion, the scenario described in your letter is like the one in our 2016 letter to Brian Latouf of General Motors, which allowed automatic activation of the hazard signal following detection of a nonresponsive driver and after the vehicle has been brought to a stop by advanced vehicle systems, and you seek our concurrence. 

Discussion 

NHTSA's interpretations of "vehicular hazard warning signal operating unit" read FMVSS No. 108 as broadly restricting automatic activation of the hazard signal.5 However, NHTSA historically has read FMVSS No. 108 to allow automatic activation on a case-by-case basis under limited circumstances consistent with the purpose of the hazard warning signal stated in
the standard. FMVSS No. 108 does not permit automatic hazard signal activations that lack any relationship to the original purpose of a hazard warning signal or could create confusion about the signal's meaning.6 

1 49 C.F.R. § 571.108.
2 Id. When activated, sufficient turn signals must flash to meet the minimum photometric requirements in FMVSS No. 108 applicable to turn signals. For the purposes of this letter, we refer to these systems collectively as activating the "hazard signal."
3 Id. The standard also defines the vehicular hazard warning signal flasher as a device which, as long as it is turned on, causes all the required turn signal lamps to flash. This system must flash when actuated by the operating unit. See id Table I-a.
4 49 C.F.R. § 571.108 S6.2. l. Under the impairment analysis NHTSA typically considers four aspects of supplemental lighting: activation pattern, brightness, color, and lamp location. In addition, the impairment analysis is applicable to supplemental lighting (i.e., lighting not required by the standard) and is closely related to the requirement that a manufacturer not "knowingly make inoperative" a compliant device or element of design. 49
U.S.C. § 30122(b). See, e.g. Letter to Paul Schaye, Feb. 9, 2019, available at
https://www.nhtsa.gov/inter.pretations/571108-ama-schaye-front-color-changing-light.
5 In letters to Mark Steele and Eric Reed in 1999 and 2000, NHTSA interpreted "a driver controlled device," to mean that that the hazard signal may not automatically activate. See Letter to Mark Steele, Feb. 25, 2000, available at https://www.nhtsa.gov/inter.pretations/2ll7lztv : and Letter to Eric Reed, Feb. 29, 2000, available at https://www.nhtsa.gov/inter.pretations/reedztv. 
6 Letter to Sen. Orrin G. Hatch, Aug. 5, 1999, available at https://www.nhtsa.gov/inter.pretations/20l80ztv. 

Per FMVSS No. 108, the purpose of the hazard warning system is "to indicate to approaching drivers the presence of a vehicular hazard." Recent interpretations have noted that "the purpose of the hazard warning is to indicate to approaching drivers that the vehicle is stopped or is proceeding at a slower rate than surrounding traffic."7 Several previous agency interpretations referenced FMVSS No. 108 S6.2.1 and emphasized that there is no ambiguity about the meaning or purpose of the hazard signal following a crash.8 Although S6.2.1 applies only to equipment not required by FMVSS No. 108, in our 2016 letter to Mr. Latouf, we clarified that the same analysis applies to automatic activation of the hazard signal.9,10 

Several letters of interpretation have discussed situations in which we believe automatic activation of the hazard signal would be inconsistent with FMVSS No. 108, such as during braking events,11 after "sudden release of the accelerator pedal,"12 or as a "deceleration warning system"13 where it would conflict with the purpose of the stop lamps.14 Most recently, on March 22, 2023, NHTSA denied a petition for decision of inconsequential noncompliance filed by

7 Letter to Brian Latouf, Nov. 18, 2016. https://www.nhtsa.gov/interpretations/16-1289-gm-hazard-innovative-28-apr-16-rsy. This statement is based on a previous statement made in our letter to Sen. Richard Lugar on May 9, 2000, that drivers in general activate the hazard signal to "indicate either that [they are] proceeding at a slower rate than surrounding traffic, or that the vehicle is stopped on or off a roadway." https://www.nhtsa.gov/interpretations/21478ztv. This was a description of typical hazard signal use and was not intended to state the purpose of the hazard warning. The letter stated the activation should depend on the driver's evaluation of the driving environment and should not occur involuntarily simply because the vehicle is decelerating. 8 Letter to Mark Steele, Feb. 25, 2000, available at https://www.nhtsa.gov/interpretations/2ll71ztv ; Letter to Timothy Bartlett, Jan. 28, 2002, available at https://www.nhtsa.gov/interpretations/23695ztv; Letter to Stephen Powers, Jan. 19, 2021, available at https://www.nhtsa.gov/interpretations/571108-help-system-powers.
9 Letter to Brian Latouf, Nov. 18, 2016, available at https://www.nhtsa.gov/interpretations/16-1289-gm-hazard­ innovative-28-apr-16-rsy. This conclusion is based in part on our longstanding position that the "use of required lighting equipment for other than its original purpose" constitutes equipment not required by the standard such that it can result in impairment. See, e.g. Letter to Sen. Orrin G. Hatch, Aug. 5, 1999, available at https://www.nhtsa.gov/interpretations/20180ztv. Automatic activation could be understood as allowed supplemental lighting (in addition to the manually controlled hazard signal) if the specific system does not impair the effectiveness of any required lighting. Because it does not influence our conclusion in this letter, we do not determine whether automatic activation of the hazard signal in the manner you describe is or is not supplemental lighting or other motor vehicle equipment.
10 NHTSA interprets FMVSS No. 108 to require that all auxiliary lamps be "steady burning," with the sole exception being auxiliary lamps that supplement required lamps that flash, such as turn signals. Letter to Donald Lane, Nov. 6 2024, available at https://www.nhtsa.gov/interpretations/ncc-230120-001-571108-peterson-trailer­ auxiliary-door-light-110624-signed. To the extent that the lighting described here could be considered supplemental lighting, NHTSA would view it as supplementing required lights that flash.
11 Daimler Trucks North America, LLC, Denial of Petition for Decision of Inconsequential Noncompliance, 88 Fed. Reg. 17291 (Mar. 22, 2023).
12 Letter to David Coburn, Aug. 6, 1999, available at https://www.nhtsa.gov/interpretations/19886ztv.
13 Letter to Jeffrey Echt, incoming received Mar. 10, 1995, available at https://www.nhtsa.gov/interpretations/aiam552l. Automatically activating the hazard signal can also interfere with other required lighting, such as the turn signals. We have also addressed cases in which other vehicle systems were activated. See, e.g. Letter to Sen. Orrin G. Hatch, Aug. 5, 1999, available at https://www.nhtsa.gov/interpretations/20l80ztv (finding activating the hazard warning system when the horn is sounded would impair the hazard warning system).
14 See Letter to Stephen Powers, Jan. 19, 2021, available at https://www.nhtsa.gov/interpretations/571108-help ­
system-powers (limiting the automatic activation of the specified system to after a crash in part because it activated the turn signals up to three times faster than the required flash rate under FMVSS No. 108). 

Daimler Trucks North America, LLC (DTNA), regarding certain Model Year 2020-2021 Freightliner Cascadia heavy trucks.15 These trucks contained a system that automatically activated the hazard signal during a brake assist application, when the brake system applies maximum braking force to assist the driver in bringing the truck to a complete stop. 

In contrast to these scenarios, our 2016 letter to Mr. Latouf addressed a similar situation to the one described in your letter. There, we stated that under FMVSS No. 108 a system could, after finding a driver unresponsive and bringing the vehicle to a stop, automatically activate the hazard signal.16 We analogized the situation to the one after a crash and noted that being at a complete stop "is the prototypical situation in which the hazard lights are intended to be used, and it is one of the situations that other motorists have come to expect when they see the hazard signal."17 However, we also stated that "the purpose of the hazard warning is to indicate to approaching drivers that the vehicle is stopped or is proceeding at a slower rate than surrounding traffic."18 We also declined to state that such activations could occur only when stopped, finding that future approaches for automatic activation of the hazard signal would be handled on a case­ by-case basis.19 

Based on our understanding of the specific circumstances described in your letter, the automatic activation of the hazard warning signal you describe is permissible under FMVSS No. 108. As an initial matter, because FMVSS No. 108 does not specify in what situations the hazard warning signal may or may not be activated, we decline to state categorically that the hazard warning signal can be automatically activated only after a vehicle has come to a complete stop. Indeed, in the letter to Mr. Latouf, we acknowledged that "proceeding at a slower rate than traffic" is a situation in which drivers typically activate the hazard warning system. 

Where past agency interpretations have opined negatively about in-motion activations, it was because the use in question was not consistent with the purpose of the hazard warning system or it impaired the effectiveness of required lighting in violation of FMVSS No. 108.20 However, your system does not appear to activate the hazard warning system in a way that we have previously found unacceptable. Instead, we view the conditions described in your letter as largely similar to those described in our letter to Mr. Latouf. 

This letter does not mean that NHTSA views FMVSS No. 108 as generally allowing the automatic use of the hazard warning signal while in motion or to indicate that a vehicle's ADAS 

15 88 Fed. Reg. 17291. We believe the circumstances of the petition are distinguishable under FMVSS No. 108. First, Subaru's system does not adjust the flash rate. Second, it activates only in the rare event of a nonresponsive driver. Third, DTNA's system specifically activated during brake events. FMVSS No. 108 states that the stop lights communicate that a vehicle is stopping or diminishing speed by braking. Therefore, the instant circumstance presents much lower risk of confusion than activation during a brake assist.
16 Letter to Brian Latouf, Nov. 18, 2016, available at https://www.nhtsa.gov/intei:pretations/16-1289-gm-hazard ­
innovative-28-apr-16-rsy.
17 Id
18 Id See Supra, note 9, for clarification regarding this quote.
19 Id
20 This letter does not rescind prior NHTSA letters of interpretation on the topic of automatic activation of the hazard warning system. 

or ADS systems are active. The presence of a nonresponsive driver creates a situation where vehicle operation and driving maneuvers are largely disabled and will be for an unknown duration, as is often true following a crash or if there is a health or mechanical issue. In such a circumstance, even if the vehicle is being decelerated to a stop, the hazard warning is not being used to communicate deceleration, activation of the stop lamps, or another action that may be the purview of a lamp required by FMVSS No. 108. Instead, the activation occurs only upon the detection of a separate hazard: a nonresponsive driver. Therefore, the risk of ambiguity or confusion of the signals is low. 

Conclusion 

Based on the information presented in your letter, the system described above would not violate FMVSS No. 108's requirements applicable to the vehicular hazard warning signal operating unit or vehicular hazard warning signal flasher. It would also not impair the effectiveness of required lighting. This interpretation is specific to the circumstances described above.

We note that Subaru indicates that when the driver is unable or unwilling to take control of the vehicle, the system will bring the vehicle to a stop. A vehicle system that stops a vehicle directly in a roadway might, depending on the circumstances, be considered to contain a safety-related defect, i.e., it may present an unreasonable risk of an accident occurring or of death and injury in an accident.21 Federal law requires the recall of a vehicle that contains a safety-related defect.22 We urge Subaru to fully consider the likely operation of the system it is contemplating and ensure that it will not present such a risk. 

Finally, activation of the hazard signal is subject to State laws, which may control when a hazard signal may be used. Nothing in this interpretation should be read to preempt State law regarding when it is appropriate for a hazard warning system to be used. We are unable to advise you on those laws, but you should ensure your system complies with any and all State laws regarding when a hazard warning system may be activated.
If you have any further questions, please contact Eli Wachtel of my staff at interpretations.NHTSA@dot.gov. 

Sincerely,

Peter Simshauser 

Chief Counsel

Dated: 7/22/25
Ref: Standard No. 108

2149 u.s.c. §§ 30102, 30118.
22 49 U.S.C. § 30118.

ID: nht69-1.30

DATE: 03/17/69

FROM: AUTHOR UNAVAILABLE; H. M. Jacklin, Jr.; NHTSA

TO: Rubber Manufacturers Association

TITLE: FMVSS INTERPRETATION

TEXT: This letter reaffirms the position of the National Highway Safety Bureau with respect to the handling of petitions for the addition of now tires as stated in recent telephone discussions with members of the Office of Standards on Accident Avoidance.

It was related during these discussions that further action on the petition of November 13, 1968, requesting the addition of the C78-13 tire size designation to Table I-J of the Appendix A of Standard No. 109 cannot be taken until the information indicating compliance with Federal Motor Vehicle Safety Standard No. 110 is received covering the desired test rim width. The Standards are directed at total motor vehicle safety; accordingly, they are just as applicable to replacement tires as to tires intended for new motor vehicles and the guidelines for the addition of new tire size designations and new alternative rims to Standards No. 109 and No. 110 as published in the Federal Register of October 5, 1968, therefore apply.

The question of a precedence having been established by the addition of the 5'JJ alternative rim to Table I of the Appendix to Standard No. 110, without supporting date, in the case of the C70-15 tire size designation has been raised by your organization. Our records indicate that your request for the addition of this tire size was based on the petition of August 19, 1968. This action was well in advance of the procedural guidelines established on October 5, 1968. Although this test rim was added to Table I of the Appendix A of Standard No. 110, without text data, the National Highway Safety Bureau believes that a safety hazard could exist if this tire and rim combination is not compatible. We would, therefore, appreciate test information certifying compliance with the requirements of Standard No. 110 by the 5'3JJ rim and the C70-15 tire size combination.

Our records indicate that you have submitted petitions dated July 11 and August 25, 1968, requesting the addition of twelve additional alternative rim sizes to Table I of Appendix A of Standard No. 110. To date, data indicating compliance with Standards No. 109 and No. 110 has not been received and we have advised you in several telephone discussions that no action is contemplated until data is submitted.

In conclusion, we would like to reiterate that all future petitions for additions to Standards No. 109 or No. 110 must be submitted in accordance with the guidelines published in the Federal Register on October 5, 1968. The Bureau makes no provisions or exceptions based on the ultimate use of the tires. All new tires will be considered within the framework of these guidelines.

ID: 16136.ztv

Mr. Richard Rawlins
Triumph Homologation
Triumph Designs, Ltd.
Dodwells Bridge Industrial Estate
Jacknell Road
Hinckley, Leicestershire
LE10 3BS
England

Dear Mr. Rawlins:

This is in reply to your fax of September 24, 1997, to Luke Loy of this agency, asking for an interpretation of Federal Motor Vehicle Safety Standard No. 108. For future reference, the Office of Chief Counsel is the appropriate office to which you should address requests for interpretations of the Federal motor vehicle safety standards.

You have asked whether rear side reflex reflectors on motorcycles must be mounted parallel to the vehicle's longitudinal centerline, or whether it is permissible to locate them approximately 9 degrees offset from the centerline.

Under Standard No. 108, lighting equipment is photometrically tested in the laboratory but must comply when installed on a motor vehicle. Thus, a reflex reflector should be mounted on the goniometer in the position in which it will be installed on a motor vehicle as well as being mounted in conformance with the specifications of SAE Standard J594f "Reflex Reflectors" January 1977, incorporated by reference in Standard No. 108. If the reflector meets the photometric requirements of SAE J594f when it is approximately 9 degrees offset from a line representing the motorcycle longitudinal centerline, then it would be permissible to mount it in an identical offset fashion on the motorcycle itself.

If you have any questions you may refer them to Taylor Vinson of this Office.

Sincerely,
John Womack
Acting Chief Counsel
ref:108
d.10/30/97

ID: nht68-4.9

DATE: 09/03/68

FROM: AUTHOR UNAVAILABLE; Robert M. O'Mahoney; NHTSA

TO: Department of California Highway Patrol

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of August 19, 1968.

You state that you do not find any provision which would permit temporary mounting of lighting devices on mobile homes and ask that we inform you what provision in Public Law 89-563 or the Federal motor vehicle safety standards permits installation of temporary devices. There is no provision in P.L. 89-563 or the standards which either permits or prohibits the temporary mounting of devices. The National Highway Safety Bureau has taken the position that, insofar as mobile homes are concerned, temporary lighting devices may be used if they meet the requirements of Standard No. 108.

With respect to your request for a copy of Docket No. 26, I enclosed a copy of the notice of request for comments recently issued and published in the Federal Register. This docket was opened several months ago and contains several hundred pages of documents. The docket is scheduled to remain open, for the receipt of additional comments, until September 10, 1968. Our rules require us to charge 50 cents per page, payable in advance for copies of docket material. should you want a copy of the complete docket, please let us know and we will advise you, after September 10, of the fee for this service.

Thank you for your continuing interest in motor vehicle safety.