Indiana Code Title 9. Motor Vehicles § 9-19-19-3

Sec. 3. (a) This section does not apply to the display of a decal required by the United States Department of Defense on the following:

(b) A person may not drive a motor vehicle with a sign, poster, sunscreening material, or other nontransparent material upon the front windshield, side wings, or side or rear windows of the vehicle that obstructs the driver's clear view of the highway or an intersecting highway. However, signs, posters, or other nontransparent material not larger than four (4) inches square may be placed upon the front windshield, side wings, or side or rear windows in the lower corner farthest removed from the driver's position.