At the opening of three days of arguments, the justices' questions suggested that they were receptive to a point on which both supporters and opponents of the law agree: that the court should decide the case now rather than waiting until the law's penalties for not having health insurance become due. On Tuesday, the court will turn to the central question in the case, the constitutionality of the law's requirement that most Americans obtain insurance or pay a penalty. The argument on Monday was a sort of appetizer to Tuesday's main course, a 90-minute debate over whether the court has the authority to hear the case yet, given an 1867 law, the Anti-Injunction Act, that says taxpayers may not challenge taxes until they become due.