Can you legally cover the fixed rear windows in a car?

I'm in Ca. and i may be wrong but i believe you CAN put tint (if that's what you mean) in rear Windows. But side Windows cannot be to dark, there is a tint guide to go by in Ca. But you should look up your states Vech. code to be sure, you should be able to find it on the web. Don't know if that helps but good luck.