On Monday, the Supreme Court considered too cases regarding how much evidence courts need before allowing plaintiffs to go to court in a class action. Both cases are in response to the Court's ruling in Wal-Mart v. Dukes, where the Court said that the plaintiffs did not have enough in common to pursue their cases as one. The justices say that these cases will help clarify their ruling in Wal-Mart, and allow courts to make better decisions on whether to declare a class action.
See "Supreme Court Hears 2 Cases Over Class Actions", Adam Liptak, The New York Times, November 5, 2012