California you're only allowed to have your rear windows tinted as dark as you like. front driver, passenger and windshield are not allowed to be tinted. You can however get a letter from a dermatologist allowing your front two windows to be tinted due to a skin condition.
I've noticed most cops are chill about front window tinting as long as you have no other visible mods on the car. If you have a loud exhaust, no front plate or even a CF hood, it gives them a reason to take a second look at the car and when writing a fix it ticket for plates or exhaust, they'll get you for tint as well. Also, remember, a fix it ticket is $25 per cited violation. So if they get you for tint and exhaust its $50 plus proof of correction.