Lately Blizzard banned players for cheating and botting in Diablo 3. Since Diablo 3 is online only, those players will have to buy another copy of the game in order to be able to play again.
In this case, you can clearly see two normative commands in collision. In one side, you have the Blizzard's Terms of Agreement, where it states that cheaters and such will be bannes. On the other side you have the Costumers Rights, that states that you have the right to consume the product you buy, the way you want.
One was made by a company trying to protect their players, and the other was made by the legislative power, made to protect all costumers.
When Blizzard bans someone, forcing him to buy another copy of the game, it's acting against the law, since you have taken away your right to consume your product. A company cannot simply make their own laws that goes against the State laws.
Legally speaking, Blizzard should only be able to ban someone based on a judicial decision, where it was proved that the acts performed by the player were against the rights of the others players.
Just something for you all to think about.