Supreme Court litigation is a bit like bread-baking. If the dough goes in the oven too soon, before it’s had enough time to rise, the end product is unpalatable. Yet at a certain point, the oven beckons. Baking is key to the process. This is the conundrum presented by the Supreme Court’s decision to tackle the subject of same-sex marriage. For those who believe in marriage equality, the court’s move is both exhilarating and scary. To understand why, remember that the court agreed to hear two very different cases. One involves the constitutionality of the Defense of Marriage Act (DOMA) and the question of whether the federal government, in states that recognize same-sex marriage, can refuse to provide some married couples the federal benefits available to others. The court was widely expected to accept the DOMA case because the law was declared unconstitutional in the lower courts. It is possible to imagine a majority — the four liberal justices and Justice Anthony M. Kennedy, most likely — agreeing. After all, the DOMA argument has overtones of federalism that ought to appeal to conservatives: the right of states to have their judgments about marriage respected by the federal government.