> AT&T Mobility v. Concepcion, 563 U.S. 333 (2011), is a legal dispute that was decided by the United States Supreme Court.[1][2] 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.[3] 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.[4]:708–09 The decision was described by Jean Sternlight as a "tsunami that is wiping out existing and potential consumer and employment class actions"[4]:704 and by law professor Myriam Gilles as "the real game-changer for class action litigation".[5] By April 2012, Concepcion was cited in at least 76 decisions sending putative class actions to individual arbitration.[6][7] After the decision, several major businesses introduced or changed arbitration terms in their consumer contracts (some of which were based on the consumer-friendly terms found in the AT&T Mobility agreement), although the hypothesis of massive adoption of consumer arbitration clauses following the decision has been disputed.

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TLDR: Class-action lawsuits against Comcast are not allowed because they include a class-action waiver in the consumer agreement.