I've never understood those laws. Hell I would knock the window out before I got it impounded. Bust the window out, pick up the glass and ask them "what window tint?"
Actually I would ask if I could just rip it off. Impounding it seems like a chickenshit move.
Roll the window down. Is there even a law that says you need to have glass anywhere in your car?
Is there a limit on motorcycle helmet visors?
A few of the reasons why those laws are stupid.