Iowa Department of Public Safety
Wallace State Office Building
Des Moines, Iowa 50319-0040
Dear Ms. Dittemore:
This responds to your letter asking whether the proposed Iowa legislation to allow light transmittance levels of 35 percent or lower on vehicle windows complies with Federal regulations (i.e., Federal Motor Vehicle Safety Standard No. 205, Glazing Materials). You also asked "does the federal government currently pursue action in states that have adopted standards that are not in compliance with federal regulations?"
As explained below, while the Iowa legislation generally would not conflict with Federal laws, the provision allowing drivers with "light-sensitive disorder permits" to have darkened windows may conflict with Federal law. Regarding your question on NHTSA's enforcement of its light transmittance requirements, NHTSA currently has no open cases on the subject. However, if it became an enforcement priority, NHTSA could enforce the 70 percent transmittance requirement in Standard No. 205 without regard to lower thresholds set by State laws.
NHTSA has the authority under 49 USC 30111 to issue Federal Motor Vehicle Safety Standards applicable to all new motor vehicles at time of first sale to the consumer. Standard No. 205 specifies performance requirements for glazing, and includes a requirement that all windows "requisite for driving visibility" (including all windows in passenger cars) have a light transmittance of at least 70 percent. Although the standard itself does not apply after the first sale of the vehicle, 49 USC 30122(b) prohibits a vehicle manufacturer, distributor, dealer, or repair business from "mak[ing] inoperative any part of a device or element of design installed
on or in a motor vehicle or motor vehicle equipment in compliance with an applicable motor vehicle safety standard . . . ." The act of tinting regulated vehicle windows to transmittance levels darker than 70 percent is a violation of this section.
Note however, that NHTSA's regulations do not apply to certain parties or actions. Vehicle owners are not restricted by Federal law in the modifications that they make to their vehicles, and could tint their windows as dark as they like without violating Federal law (although NHTSA does not encourage tinting darker than Standard No. 205 allows). Federal law also does not regulate the operation or use of vehicles, which is under the jurisdiction of the States.
Under certain circumstances, State laws would be preempted by Federal law. 49 USC 30103(b)(1) states "[w]hen a motor vehicle safety standard is in effect . . . a State . . . may prescribe . . . a standard applicable to the same aspect of performance . . . only if the standard is identical to the [federal standard]." The State laws would be preempted by the Federal law to the extent that they regulate the same aspect of performance in a different way, or permit something that is prohibited by the Federal regulations. We explained in a July 30, 1990 response to a similar inquiry from you (enclosed) that, as long as the State legislation restricts itself to regulating the operation or use (as opposed to sale or modification) of vehicles, it would not be preempted by Federal law. By merely regulating the degree of tint in vehicles registered in the State or used on its roads, some States specify a lower transmittance level than the Federally required 70 percent.
I would summarize the legislation you sent us as prohibiting a person from operating on Iowa highways a motor vehicle requiring Iowa registration if: (1) any sunscreening device or transparent material (hereafter referred to as tinting material) is applied to the vehicle's windshield below five inches from the top of the windshield or the AS-1 line, (2) tinting material applied to any other window reduces the light transmittance of the glazing below 30 percent (accounting for the 5 percent tolerance), or is reflective, or is red, amber, or yellow in color, (3) tinting material is applied to any window to the rear of the driver and the vehicle is not equipped with left and right side rearview mirrors. The above restrictions do not apply to windows behind the driver of a "motor truck," bus, recreational vehicle, multipurpose vehicle, or any motor vehicle with a light-sensitive disorder permit affixed.
All of these provisions mentioned in the summary above only regulate the operation of vehicles, or the applicability of Iowa's law, so there is no explicit conflict with the Federal law. However, as we stated in our previous letter, we do not understand why the State of Iowa would conclude that the safety need that justifies requiring not less than 70 percent light transmittance in new vehicles is satisfied by allowing light transmittance levels as low as 30 percent in vehicles to be operated in the State.
There is one aspect of the proposed legislation that we believe could cause confusion and lead tint film installers to violate Federal law. The legislation states "[a] person suffering from a light sensitive disorder may operate a motor vehicle equipped with windows with less than thirty-five percent light transmittance on the side and rear windows, if that person has a light-sensitive disorder permit [issued by the State]." (Emphasis added). Taken literally, this language is not preempted because it restricts itself to the issue of operation, without addressing how the windows got so dark in the first place. However, most State laws prohibit certain behaviors, while the word "may" in your proposed legislation is permissive.
People reading the permissive language in this proposal may assume that there are no restrictions on installing very dark tinting material so long as a State permit has been issued. However, if a vehicle manufacturer, distributor, dealer, or repair business installs such dark tinting material, they would violate the Federal prohibition against "mak[ing] inoperative" a piece of motor vehicle equipment. We suggest that, before the proposal becomes law, you add some language expressly stating the permissive language does not permit installation of tinting material by these parties.
I hope this information is helpful. If you have any further questions, please feel free to contact Paul Atelsek of my staff at this address or by telephone at (202) 366-2992.
Acting Chief Counsel