Each state, Canadian province and Puerto Rico has tint laws governing the darkness, reflectivity and colors allowed on vehicles. Window tinting laws vary from state to state and can change quickly. Before installing any window film on any vehicle, consult your local law enforcement for laws regarding the correct use and legal installation of any aftermarket window film that will be applied to your vehicle. Below are links to tint laws as published by the International Window Film Association

US State Auto Tint Laws