"On April 27, 2011, the Court ruled, by a 5–4 margin, that the Federal Arbitration Act of 1925 preempts state laws that prohibit contracts from disallowing class-wide arbitration, such as the law previously upheld by the California Supreme Court in the case of Discover Bank v. Superior Court. As a result, businesses that include arbitration agreements with class action waivers can require consumers to bring claims only in individual arbitrations, rather than in court as part of a class action."

After this decision, tons of click-wrap ("contracts of adhesion") agreements added "oh BTW you can't join a class-action suit against us." They seem to be on very solid legal ground. :-(