"Where, in the performance of its judicial duties, the Court decides a case in such a way as to resolve the sort of intensely divisive controversy reflected in Roe and those rare, comparable cases, its decision has a dimension that the resolution of the normal case does not carry. It is the dimension present whenever the Court's interpretation of the Constitution calls the contending sides of a national controversy to end their national division by accepting a common mandate rooted in the Constitution. The Court is not asked to do this very often, having thus addressed the Nation only twice in our lifetime, in the decisions of Brown and Roe. But when the Court does act in this way, its decision requires an equally rare precedential force to counter the inevitable efforts to overturn it and to thwart its implementation. Some of those efforts may be mere unprincipled emotional reactions; others may proceed from principles worthy of profound respect. But whatever the premises of opposition may be, only the most convincing justification under accepted standards of precedent could suffice to demonstrate that a later decision overruling the first was anything but a surrender to political pressure, and an unjustified repudiation of the principle on which the Court staked its authority in the first instance. So to overrule under fire in the absence of the most compelling reason to reexamine a watershed decision would subvert the Court's legitimacy beyond any serious question. Cf. Brown v. Board of Education, 349 U.S. 294, 300, 75 S.Ct. 753, 756, 99 L.Ed. 1083 (1955) (Brown II ) ("[I]t should go without saying that the vitality of th[e] constitutional principles [announced in Brown v. Board of Education, 347 U.S. 483, 74 S.Ct. 686, 98 L.Ed. 873 (1954),] cannot be allowed to yield simply because of disagreement with them"). The country's loss of confidence in the judiciary would be underscored by an equally certain and equally reasonable condemnation for another failing in overruling unnecessarily and under pressure. Some cost will be paid by anyone who approves or implements a constitutional decision where it is unpopular, or who refuses to work to undermine the decision or to force its reversal. The price may be criticism or ostracism, or it may be violence. An extra price will be paid by those who themselves disapprove of the decision's results when viewed outside of constitutional terms, but who nevertheless struggle to accept it, because they respect the rule of law. To all those who will be so tested by following, the Court implicitly undertakes to remain steadfast, lest in the end a price be paid for nothing. The promise of constancy, once given, binds its maker for as long as the power to stand by the decision survives and the understanding of the issue has not changed so fundamentally as to render the commitment obsolete. From the obligation of this promise this Court cannot and should not assume any exemption when duty requires it to decide a case in conformance with the Constitution. A willing breach of it would be nothing less than a breach of faith, and no Court that broke its faith with the people could sensibly expect credit for principle in the decision by which it did that."