Section 321.438 of the 2007 edition of the Code of Iowa states the following:
"321.438 Windshields and windows.
1. A person shall not drive a motor vehicle equipped with a windshield, sidewings, or side or rear windows which do not permit clear vision.
2. A person shall not operate on the highway a motor vehicle equipped with a front windshield, a side window to the immediate right or left of the driver, or a side-wing forward of and to the left or right of the driver which is excessively dark or reflective so that it is difficult for a person outside the motor vehicle to see into the motor vehicle through the windshield, window, or sidewing. The department shall adopt rules establishing a minimum measurable standard of transparency which shall apply to violations of this subsection.
3. Every motor vehicle except a motorcycle, or a vehicle included in the provisions of section 321.383 or section 321.115 shall be equipped with a windshield in accordance with section 321.444 .
[C39, § 5034.47; C46, 50, 54, 58, 62, 66, 71, 73, 75, 77, 79, 81, §321.438 ]
For applicable scheduled fine, see § 805.8A , subsection 3, paragraph c "
The Iowa Administrative Rules / Iowa Administrative Code for the Iowa Department of Transportation state the following:
"761—450.7(321)
Front windshields, windows or sidewings.
450.7(1)
Prohibition.
Pursuant to Iowa Code subsection 321.438(2), a person shall not operate on the highway a motor vehicle equipped with a front windshield, a side window to the immediate right or left of the driver (front side window) or a sidewing forward of and to the left or right of the driver (front sidewing) which is excessively dark or reflective.
450.7(2)
Standard of transparency.
“Excessively dark or reflective” means that the windshield, front side window or front sidewing does not meet a minimum standard of transparency of 70 percent light transmittance.
450.7(3)
Dark window exemption.
a.
A person suffering from a severe light-sensitive condition may be exempt from the standard of transparency if the need is documented by a physician. The exemption does not apply to a commercial vehicle.
b.
A passenger or operator of a motor vehicle who for medical reasons requires a front windshield, a front side window or a front sidewing with less than 70 percent but not less than 35 percent light transmittance may obtain Form 432020 to be signed by the person’s physician and carried at all times in the vehicle to which the exemption applies. Form 432020 is available from the office of vehicle services.
c.
“Physician” as used in this rule means a person licensed under Iowa Code chapter 148, 150, 150A, 151 or 154.
This rule is intended to implement Iowa Code section 321.438."