So, if this lawsuit wins, the ISPs get to keep selling user information. Users can't really stop this, due to the fact that most locations have only one (or, if they're lucky, two) providers.
The law that the lawsuit is fighting says that they have to get permission from their users before they sell said information.
If the lawsuit wins (and strikes down the law), the free speech of the ISP's users is squashed. If the lawsuit loses, the users' free speech is protected, and the ISPs can no longer sell the users' information without permission. I kinda hate that the right to make money is now considered a free speech right here.