Americans today are inclined to accept, without thinking much about it, the idea of judicial supremacy. We think that the federal courts—and especially the Supreme Court—have an extensive discretion to decide for us the big questions of public policy that come before the nation. After all, the Supreme Court has taken upon itself the authority to decide whether and to what extent abortion may be regulated, and, more recently, to decide the definition of marriage. Moreover, we think that that court’s decisions on such questions are final, that there is no way the people or their representatives can effectively assert...