"So in this case we may inquire whether Roe's central rule has been found unworkable; whether the rule's limitation on state power could be removed without serious inequity to those who have relied upon it or significant damage to the stability of the society governed by the rule in question; whether the law's growth in the intervening years has left Roe's central rule a doctrinal anachronism discounted by society; and whether Roe's premises of fact have so far changed in the ensuing two decades as to render its central holding somehow irrelevant or unjustifiable in dealing with the issue it addressed. Although Roe has engendered opposition, it has in no sense proven "unworkable," see Garcia v. San Antonio Metropolitan Transit Authority, 469 U.S. 528, 546, 105 S.Ct. 1005, 1015, 83 L.Ed.2d 1016 (1985), representing as it does a simple limitation beyond which a state law is unenforceable. While Roe has, of course, required judicial assessment of state laws affecting the exercise of the choice guaranteed against government infringement, and although the need for such review will remain as a consequence of today's decision, the required determinations fall within judicial competence."