As I understand it, the AT&T case determined that clauses restricting consumers from engaging in class action lawsuits were legal. But in the Sony case, their clause restricts a consumer from suing in court and instead, must bring the arbitration to a neutral body (but not court). This scenario seems much more harmful and possibly infringes on a very, very important right.
The AT&T case was not specifically about class until it hit the SCOTUS. The case was originally found for AT&T, with the court finding the clause was fine. The California Federal Circuit court reversed that decision, because it felt the clause was 'unconscionable' because it also signed away the right to sue as a class. The SCOTUS rejected that interpretation, upholding not only clauses that deny the right to sue as a class, but the arbitration clause itself.
