Businesses targeted by class actions for inflicting massive aggregate harm have sought ways to avoid class actions altogether. In the 1990s, the U.S. Supreme Court issued a number of decisions which strengthened the "federal policy favoring arbitration". In response, lawyers have added provisions to consumer contracts of adhesion called "collective action waivers", which prohibit those signing the contracts from bringing class-action suits. In 2011, the U.S. Supreme Court ruled in a 5–4 decision in "AT&T Mobility v. Concepcion" that the Federal Arbitration Act of 1925 preempts state laws that prohibit contracts from disallowing class-action lawsuits, which will make it more difficult for consumers to file class-action lawsuits. The dissent pointed to a saving clause in the federal act which allowed states to determine how a contract or its clauses may be revoked.