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 inter vening 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.

1

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 (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.

2

The inquiry into reliance counts the cost of a rule's repudiation as it would fall on those who have relied reasonably on the rule's continued application. Since the classic case for weighing reliance heavily in favor of following the earlier rule occurs in the commercial context, see Payne v. Tennessee, supra, at ____ (slip op., at ___), where advance planning of great precision is most obviously a necessity, it is no cause for surprise that some would find no reliance worthy of consideration in support of Roe.

While neither respondents nor their amici in so many words deny that the abortion right invites some reliance prior to its actual exercise, one can readily imagine an argument stressing the dissimilarity of this case to one involving property or contract. Abortion is customarily chosen as an unplanned response to the consequence of unplanned activity or to the failure of conventional birth control, and except on the assumption that no intercourse would have occurred but for Roe's holding, such behavior may appear to justify no reliance claim. Even if reliance could be claimed on that unrealistic assumption, the argument might run, any reliance interest would be de minimis. This argument would be premised on the hypothesis that reproductive planning could take virtually immediate account of any sudden restoration of state authority to ban abortions.

To eliminate the issue of reliance that easily, however, one would need to limit cognizable reliance to specific instances of sexual activity. But to do this would be simply to refuse to face the fact that for two decades of economic and social developments, people have organized intimate relationships and made choices that define their views of themselves and their places in society, in reliance on the availability of abortion in the event that contraception should fail. The ability of women to participate equally in the economic and social life of the Nation has been facilitated by their ability to control their reproductive lives. See, e.g., R. Petchesky, Abortion and Woman's Choice 109, 133, n. 7 (rev. ed. 1990). The Constitution serves human values, and while the effect of reliance on Roe cannot be exactly measured, neither can the certain cost of overruling Roe for people who have ordered their thinking and living around that case be dismissed.

3

No evolution of legal principle has left Roe's doctrinal footings weaker than they were in 1973. No development of constitutional law since the case was decided has implicitly or explicitly left Roe behind as a mere survivor of obsolete constitutional thinking.

It will be recognized, of course, that Roe stands at an intersection of two lines of decisions, but in whichever doctrinal category one reads the case, the result for present purposes will be the same. The Roe Court itself placed its holding in the succession of cases most prominently exemplified by Griswold v. Connecticut, 381 U. S. 479 (1965), see Roe, 410 U. S., at 152-153. When it is so seen, Roe is clearly in no jeopardy, since subsequent constitutional developments have neither disturbed, nor do they threaten to diminish, the scope of recognized protection accorded to the liberty relating to intimate relationships, the family, and decisions about whether or not to beget or bear a child. See, e.g., Carey v. Population Services International, 431 U. S. 678 (1977); Moore v. East Cleveland, 431 U. S. 678 (1977).

Roe, however, may be seen not only as an exemplar of Griswold liberty but as a rule (whether or not mistaken) of personal autonomy and bodily integrity, with doctrinal affinity to cases recognizing limits on governmental power to mandate medical treatment or to bar its rejection. If so, our cases since Roe accord with Roe's view that a State's interest in the protection of life falls short of justifyingany plenary override of individual liberty claims. Cruzan v. Director, Missouri Dept. of Health, 497 U.S. 261,278 (1990); Cf., e.g., Riggins v. Nevada, 504 U.S. ____, ____ (1992) (slip. op., at 7); Washington v.

Harper, 494 U. S.210 (1990); see also, e.g., Rochin v. California, 342 U.S. 165 (1952); Jacobson v. Massachusetts, 197 U. S. 11, 24-30 (1905).

Finally, one could classify Roe as sui generis. If the case is so viewed, then there clearly has been no erosion of its central determination. The original holding resting on the concurrence of seven Members of the Court in 1973 was expressly affirmed by a majority of six in 1983, see Akron v. Akron Center for Reproductive Health, Inc., 462 U.S. 416 (1983) (Akron I), and by a majority of five in 1986, see Thornburgh v. American College of Obstetricians and Gynecologists, 476 U. S. 747 (1986), expressing adherence to the constitutional ruling despite legislative efforts in some States to test its limits. More recently, in Webster v. Reproductive Health Services, 492 U. S. 490 (1989), although two of the present authors questioned the trimester framework in a way consistent with our judgment today, see id., at 518 (Rehnquist C. J., joined by White, and Kennedy, JJ.); id., at 529 (O'Connor, J., concurring in part and concurring in judgment), a majority of the Court either decided to reaffirm or declined to address the constitutional validity of the central holding of Roe. See Webster, 492 U. S., at 521 (Rehnquist, C. J., joined by White and Kennedy, JJ.); id., at 525-526 (O'Con- nor, J., concurring in part and concurring in judgment); id., at 537, 553 (Blackmun, J., joined by Brennan and Marshall, JJ., concurring in part and dissenting in part); id., at 561-563 (Stevens, J., concurring in part and dissenting in part).

Nor will courts building upon Roe be likely to hand down erroneous decisions as a consequence. Even on the assumption that the central holding of Roe was in error, that error would go only to the strength of the state interest in fetal protection, not to the recognition afforded by the Constitution to the woman's liberty. The latter aspect of the decision fits comfortably within the framework of the Court's prior decisions including Skinner v. Oklahoma ex rel. Williamson, 316 U. S. 535 (1942), Griswold, supra, Loving v. Virginia, 388 U. S. 1 (1967), and Eisenstadt v. Baird, 405 U. S. 438 (1972), the holdings of which are not a series of isolated points, but mark a rational continuum. Poe v. Ullman, 367 U. S., at 543 (1961) (Harlan, J., dissenting). As we described in Carey v. Population Services International, supra, the liberty which encompasses those decisions includes `the interest in independence in making certain kinds of important decisions.' While the outer limits of this aspect of [protected liberty] have not been marked by the Court, it is clear that among the decisions that an individual may make without unjustified government interference are personal decisions `relating to marriage, procreation, contraception, family relationships, and child rearing and education.' Id., at 684-685 (citations omitted). The soundness of this prong of the Roe analysis is apparent from a consideration of the alternative. If indeed the woman's interest in deciding whether to bear and beget a child had not been recognized as in Roe, the State might as readily restrict a woman's right to choose to carry a pregnancy to term as to terminate it, to further asserted state interests in population control, or eugenics, for example. Yet Roe has been sensibly relied upon to counter any such suggestions. E.g., Arnold v. Board of Education of Escambia County, Ala., 880 F. 2d 305, 311 (CA11 1989) (relying upon Roe and concluding that government officials violate the Constitution by coercing a minor to have an abortion); Avery v. County of Burke, 660 F. 2d 111, 115 (CA4 1981) (county agency inducing teenage girl to undergo unwanted sterilization on the basis of misrepresentation that she had sickle cell trait); see also In re Quinlan, 70 N.J. 10, 355 A. 2d 647, cert. denied sub nom. Garger v. New Jersey, 429 U. S. 922 (1976) (relying on Roe in finding a right to terminate medical treatment). In any event, because Roe's scope is confined by the fact of its concern with postconception potential life, a concern otherwise likely to be implicated only by some forms of contraception protected independently under Griswold and later cases, any error in Roe is unlikely to have serious ramifications in future cases.

/* The Court does not dwell on the fact that the states not only used to outlaw abortion, but in many cases, they also required forced sterilizations. Roe also can be seen to limit (or even prohibit) state laws, active into the 1970's where those below certain IQ's were sterilized. */

4

We have seen how time has overtaken some of Roe's factual assumptions: advances in maternal health care allow for abortions safe to the mother later in pregnancy than was true in 1973, see Akron I, supra, at 429, n. 11, and advances in neonatal care have advanced viability to a point somewhat earlier. Compare Roe, 410 U. S., at 160, with Webster, supra, at 515-516 (opinion of Rehnqu- ist, C.J.); see Akron I, supra, at 457, and n. 5 (O'Connor, J., dissenting). But these facts go only to the scheme of time limits on the realization of competing interests, and the divergences from the factual premises of 1973 have no bearing on the validity of Roe's central holding, that viability marks the earliest point at which the State's interest in fetal life is constitutionally adequate to justify a legislative ban on nontherapeutic abortions. The soundness or unsoundness of that constitutional judgment in no sense turns on whether viability occurs at approximately 28 weeks, as was usual at the time of Roe, at 23 to 24 weeks, as it sometimes does today, or at some moment even slightly earlier in pregnancy, as it may if fetal respiratory capacity can somehow be enhanced in the future. Whenever it may occur, the attainment of viability may continue to serve as the critical fact, just as it has done since Roe was decided; which is to say that no change in Roe's factual underpinning has left its central holding obsolete, and none supports an argument for overruling it.

5

The sum of the precedential inquiry to this point shows Roe's underpinnings unweakened in any way affecting its central holding. While it has engendered disapproval, it has not been unworkable. An entire generation has come of age free to assume Roe's concept of liberty in defining the capacity of women to act in society, and to make reproductive decisions; no erosion of principle going to liberty or personal autonomy has left Roe's central holding a doctrinal remnant; Roe portends no developments at odds with other precedent for the analysis of personal liberty; and no changes of fact have rendered viability more or less appropriate as the point at which the balance of interests tips. Within the bounds of normal stare decisis analysis, then, and subject to the considerations on which it customarily turns, the stronger argument is for affirming Roe's central holding, with whatever degree of personal reluctance any of us may have, not for overruling it.

/* This analysis is quite similar to that of "liberty interest" as applied to the states. A state does not have to accord certain types of rights to its citizens; but once it does, the revocation or limitation of the privileges must be pursuant to due process. The Court argues here that it grant an expectation of the right to abortions during the early part of pregnancy and thus should not cavalierly overrule the same. */

B

In a less significant case, stare decisis analysis could, and would, stop at the point we have reached. But the sustained and widespread debate Roe has provoked calls for some comparison between that case and others of comparable dimension that have responded to national controversies and taken on the impress of the controversies addressed. Only two such decisional lines from the past century present themselves for examination, and in each instance the result reached by the Court accorded with the principles we apply today.

The first example is that line of cases identified with Lochner v. New York, 198 U. S. 45 (1905), which imposed substantive limitations on legislation limiting economic autonomy in favor of health and welfare regulation, adopting, in Justice Holmes' view, the theory of laissez-faire. Id., at 75 (Holmes, J., dissenting). The Lochner decisions were exemplified by Adkins v. Children's Hospital of D.C., 261 U. S. 525 (1923), in which this Court held it to be an infringement of constitutionally protected liberty of contract to require the employers of adult women to satisfy minimum wage standards. Fourteen years later, West Coast Hotel Co. v. Parrish, 300 U. S. 379 (1937), signalled the demise of Lochner by overruling Adkins. In the meantime, the Depression had come and, with it, the lesson that seemed unmistakable to most people by 1937, that the interpretation of contractual freedom protected in Adkins rested on fundamentally false factual assumptions about the capacity of a relatively unregulated market to satisfy minimal levels of human welfare. See West Coast Hotel Co., supra, at 399. As Justice Jackson wrote of the constitutional crisis of 1937 shortly before he came on the bench, The older world of laissez faire was recognized everywhere outside the Court to be dead. R. Jackson, The Struggle for Judicial Supremacy 85 (1941). The facts upon which the earlier case had premised a constitutional resolution of social controversy had proved to be untrue, and history's demonstration of their untruth not only justified but required the new choice of constitutional principle that West Coast Hotel announced. Of course, it was true that the Court lost something by its misperception, or its lack of prescience, and the Court-packing crisis only magnified the loss; but the clear demonstration that the facts of economic life were different from those previously assumed warranted the repudiation of the old law.

The second comparison that 20th century history invites is with the cases employing the separate-but-equal rule for applying the Fourteenth Amendment's equal protection guarantee. They began with Plessy v. Ferguson, 163 U. S. 537 (1896), holding that legislatively mandated racial segregation in public transportation works no denial of equal protection, rejecting the argument that racial separation enforced by the legal machinery of American society treats the black race as inferior. The Plessy Court considered the underlying fallacy of the plaintiff's argument to consist in the assumption that the enforced separation of the two races stamps the colored race with a badge of inferiority. If this be so, it is not by reason of anything found in the act, but solely because the colored race chooses to put that construction upon it. Id., at at 551. Whether, as a matter of historical fact, the Justices in the Plessy majority believed this or not, see id., at 557, 562 (Harlan, J., dissenting), this understanding of the implication of segregation was the stated justification for the Court's opinion. But this understanding of the facts and the rule it was stated to justify were repudiated in Brown v. Board of Education, 347 U. S. 483 (1954). As one commentator observed, the question before the Court in Brown was whether discrimination inheres in that segregation which is imposed by law in the twentieth century in certain specific states in the American Union. And that question has meaning and can find an answer only on the ground of history and of common knowledge about the facts of life in the times and places afore- said. Black, The Lawfulness of the Segregation Decisions, 69 Yale L. J. 421, 427 (1960).

The Court in Brown addressed these facts of life by observing that whatever may have been the understanding in Plessy's time of the power of segregation to stigmatize those who were segregated with a badge of inferiority, it was clear by 1954 that legally sanctioned segregation had just such an effect, to the point that racially separate public educational facilities were deemed inherently unequal. 374 U. S., at 494-495. Society's understanding of the facts upon which a constitutional ruling was sought in 1954 was thus fundamentally different from the basis claimed for the decision in 1896. While we think Plessy was wrong the day it was decided, see Plessy, supra, at 552-564 (Harlan, J., dissenting), we must also recognize that the Plessy Court's explanation for its decision was so clearly at odds with the facts apparent to the Court in 1954 that the decision to reexamine Plessy was on this ground alone not only justified but required.

West Coast Hotel and Brown each rested on facts, or an understanding of facts, changed from those which furnished the claimed justifications for the earlier constitutional resolutions. Each case was comprehensible as the Court's response to facts that the country could understand, or had come to understand already, but which the Court of an earlier day, as its own declarations disclosed, had not been able to perceive. As the decisions were thus comprehensible they were also defensible, not merely as the victories of one doctrinal school over another by dint of numbers (victories though they were), but as applications of constitutional principle to facts as they had not been seen by the Court before. In constitutional adjudication as elsewhere in life, changed circumstances may impose new obligations, and the thoughtful part of the Nation could accept each decision to overrule a prior case as a response to the Court's constitutional duty.

/* Perhaps President Roosevelts threat to pack the court if it did not stop overruling all of the new deal legislation is also relevant. */

Because the case before us presents no such occasion it could be seen as no such response. Because neither the factual underpinnings of Roe's central holding nor our understanding of it has changed (and because no other indication of weakened precedent has been shown) the Court could not pretend to be reexamining the prior law with any justification beyond a present doctrinal disposition to come out differently from the Court of 1973. To overrule prior law for no other reason than that would run counter to the view repeated in our cases, that a decision to overrule should rest on some special reason over and above the belief that a prior case was wrongly decided. See, e.g., Mitchell v. W.T. Grant, 416 U. S. 600, 636 (1974) (Stewart, J., dissenting) ( A basic change in the law upon a ground no firmer than a change in our membership invites the popular misconception that this institution is little different from the two political branches of the Government. No misconception could do more lasting injury to this Court and to the system of law which it is our abiding mission to serve); Mapp v. Ohio, 367 U. S. 643, 677 (1961) (Harlan, J., dissenting).

C

The examination of the conditions justifying the repudiation of Adkins by West Coast Hotel and Plessy by Brown is enough to suggest the terrible price that would have been paid if the Court had not overruled as it did. In the present case, however, as our analysis to this point makes clear, the terrible price would be paid for overruling. Our analysis would not be complete, however, without explaining why overruling Roe's central holding would not only reach an unjustifiable result under principles of stare decisis, but would seriously weaken the Court's capacity to exercise the judicial power and to function as the Supreme Court of a Nation dedicated to the rule of law. To understand why this would be so it is necessary to understand the source of this Court's authority, the conditions necessary for its preservation, and its relationship to the country's understanding of itself as a constitutional Republic.

The root of American governmental power is revealed most clearly in the instance of the power conferred by the Constitution upon the Judiciary of the United States and specifically upon this Court. As Americans of each succeeding generation are rightly told, the Court cannot buy support for its decisions by spending money and, except to a minor degree, it cannot independently coerce obedience to its decrees. The Court's power lies, rather, in its legitimacy, a product of substance and perception that shows itself in the people's acceptance of the Judiciary as fit to determine what the Nation's law means and to declare what it demands.

The underlying substance of this legitimacy is of course the warrant for the Court's decisions in the Constitution and the lesser sources of legal principle on which the Court draws. That substance is expressed in the Court's opinions, and our contemporary understanding is such that a decision without principled justification would be no judicial act at all. But even when justification is furnished by apposite legal principle, something more is required. Because not every conscien- tious claim of principled justification will be accepted as such, the justification claimed must be beyond dispute. The Court must take care to speak and act in ways that allow people to accept its decisions on the terms the Court claims for them, as grounded truly in principle, not as compromises with social and political pressures having, as such, no bearing on the principled choices that the Court is obliged to make. Thus, the Court's legitimacy depends on making legally principled decisions under circumstances in which their principled character is sufficiently plausible to be accepted by the Nation.

The need for principled action to be perceived as such is implicated to some degree whenever this, or any other appellate court, overrules a prior case. This is not to say, of course, that this Court cannot give a perfectly satisfactory explanation in most cases. People understand that some of the Constitution's language is hard to fathom and that the Court's Justices are sometimes able to perceive significant facts or to understand principles of law that eluded their predecessors and that justify departures from existing decisions. However upsetting it may be to those most directly affected when one judicially derived rule replaces another, the country can accept some correction of error without necessarily questioning the legitimacy of the Court.

In two circumstances, however, the Court would almost certainly fail to receive the benefit of the doubt in overruling prior cases. There is, first, a point beyond which frequent overruling would overtax the country's belief in the Court's good faith. Despite the variety of reasons that may inform and justify a decision to overrule, we cannot forget that such a decision is usually perceived (and perceived correctly) as, at the least, a statement that a prior decision was wrong. There is a limit to the amount of error that can plausibly be imputed to prior courts. If that limit should be exceeded, disturbance of prior rulings would be taken as evidence that justifiable reexamination of principle had given way to drives for particular results in the short term. The legitimacy of the Court would fade with the frequency of its vacillation.

That first circumstance can be described as hypothetical; the second is to the point here and now. 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 contro- versy 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 (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 (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.

It is true that diminished legitimacy may be restored, but only slowly. Unlike the political branches, a Court thus weakened could not seek to regain its position with a new mandate from the voters, and even if the Court could somehow go to the polls, the loss of its principled character could not be retrieved by the casting of so many votes. Like the character of an individual, the legitimacy of the Court must be earned over time. So, indeed, must be the character of a Nation of people who aspire to live according to the rule of law. Their belief in themselves as such a people is not readily separable from their understanding of the Court invested with the authority to decide their constitutional cases and speak before all others for their constitutional ideals. If the Court's legitimacy should be undermined, then, so would the country be in its very ability to see itself through its constitutional ideals. The Court's concern with legitimacy is not for the sake of the Court but for the sake of the Nation to which it is responsible.

The Court's duty in the present case is clear. In 1973, it confronted the already-divisive issue of governmental power to limit personal choice to undergo abortion, for which it provided a new resolution based on the due process guaranteed by the Fourteenth Amendment. Whether or not a new social consensus is developing on that issue, its divisiveness is no less today than in 1973, and pressure to overrule the decision, like pressure to retain it, has grown only more intense. A decision to overrule Roe's essential holding under the existing circumstances would address error, if error there was, at the cost of both profound and unnecessary damage to the Court's legitimacy, and to the Nation's commitment to the rule of law. It is therefore imperative to adhere to the essence of Roe's original decision, and we do so today.

IV

From what we have said so far it follows that it is a constitutional liberty of the woman to have some freedom to terminate her pregnancy. We conclude that the basic decision in Roe was based on a constitutional analysis which we cannot now repudiate. The woman's liberty is not so unlimited, however, that from the outset the State cannot show its concern for the life of the unborn, and at a later point in fetal development the State's interest in life has sufficient force so that the right of the woman to terminate the pregnancy can be restricted.

That brings us, of course, to the point where much criticism has been directed at Roe, a criticism that always inheres when the Court draws a specific rule from what in the Constitution is but a general standard. We conclude, however, that the urgent claims of the woman to retain the ultimate control over her destiny and her body, claims implicit in the meaning of liberty, require us to perform that function. Liberty must not be extinguished for want of a line that is clear. And it falls to us to give some real substance to the woman's liberty to determine whether to carry her pregnancy to full term.

We conclude the line should be drawn at viability, so that before that time the woman has a right to choose to terminate her pregnancy. We adhere to this principle for two reasons. First, as we have said, is the doctrine of stare decisis. Any judicial act of line-drawing may seem somewhat arbitrary, but Roe was a reasoned statement, elaborated with great care. We have twice reaffirmed it in the face of great opposition. See Thornburgh v. American College of Obstetricians & Gynecologists, 476 U. S., at 759; Akron I, 462 U. S., at 419-420. Although we must overrule those parts of Thornburgh and Akron I which, in our view, are inconsistent with Roe's statement that the State has a legitimate interest in promoting the life or potential life of the unborn, see infra, at ___, the central premise of those cases represents an unbroken commitment by this Court to the essential holding of Roe. It is that premise which we reaffirm today.

The second reason is that the concept of viability, as we noted in Roe, is the time at which there is a realistic possibility of maintaining and nourishing a life outside the womb, so that the independent existence of the second life can in reason and all fairness be the object of state protection that now overrides the rights of the woman. See Roe v. Wade, 410 U. S., at 163. Consistent with other constitutional norms, legislatures may draw lines which appear arbitrary without the necessity of offering a justification. But courts may not. We must justify the lines we draw. And there is no line other than viability which is more workable. To be sure, as we have said, there may be some medical developments that affect the precise point of viability, see supra, at ___, but this is an imprecision within tolerable limits given that the medical community and all those who must apply its discoveries will continue to explore the matter. The viability line also has, as a practical matter, an element of fairness. In some broad sense it might be said that a woman who fails to act before viability has consented to the State's intervention on behalf of the developing child.

The woman's right to terminate her pregnancy before viability is the most central principle of Roe v. Wade. It is a rule of law and a component of liberty we cannot renounce.

On the other side of the equation is the interest of the State in the protection of potential life. The Roe Court recognized the State's important and legitimate interest in protecting the potentiality of human life. Roe, supra, at 162. The weight to be given this state interest, not the strength of the woman's interest, was the difficult question faced in Roe. We do not need to say whether each of us, had we been Members of the Court when the valuation of the State inter- est came before it as an original matter, would have concluded, as the Roe Court did, that its weight is insufficient to justify a ban on abor- tions prior to viability even when it is subject to certain exceptions. The matter is not before us in the first instance, and coming as it does after nearly 20 years of litigation in Roe's wake we are satisfied that the immediate question is not the soundness of Roe's resolution of the issue, but the precedential force that must be accorded to its holding. And we have concluded that the essential holding of Roe should be reaffirmed.

Yet it must be remembered that Roe v. Wade speaks with clarity in establishing not only the woman's liberty but also the State's important and legitimate interest in potential life. Roe, supra, at 163. That portion of the decision in Roe has been given too little acknowledgement and implementation by the Court in its subsequent cases. Those cases decided that any regulation touching upon the abortion decision must survive strict scrutiny, to be sustained only if drawn in narrow terms to further a compelling state interest. See, e.g., Akron I, supra, at 427. Not all of the cases decided under that formulation can be reconciled with the holding in Roe itself that the State has legitimate interests in the health of the woman and in protecting the potential life within her. In resolving this tension, we choose to rely upon Roe, as against the later cases.

Roe established a trimester framework to govern abortion regulations. Under this elaborate but rigid construct, almost no regulation at all is permitted during the first trimester of pregnancy; regulations designed to protect the woman's health, but not to further the State's interest inpotential life, are permitted during the second trimester; and during the third trimester, when the fetus is viable, prohibitions are permitted provided the life or health of the mother is not at stake. Roe v. Wade, supra, at 163-166. Most of our cases since Roe have involved the application of rules derived from the trimester framework. See, e.g., Thornburgh v. American College of Obstetricians and Gynecologists, supra; Akron I, supra.

The trimester framework no doubt was erected to ensure that the woman's right to choose not become so subordinate to the State's interest in promoting fetal life that her choice exists in theory but not in fact. We do not agree, however, that the trimester approach is necessary to accomplish this objective. A framework of this rigidity was unnecessary and in its later interpretation sometimes contradicted the State's permissible exercise of its powers.

Though the woman has a right to choose to terminate or continue her pregnancy before viability, it does not at all follow that the State is prohibited from taking steps to ensure that this choice is thoughtful and informed. Even in the earliest stages of pregnancy, the State may enact rules and regulations designed to encourage her to know that there are philosophic and social arguments of great weight that can be brought to bear in favor of continuing the pregnancy to full term and that there are procedures and institutions to allow adoption of unwanted children as well as a certain degree of state assistance if the mother chooses to raise the child herself. `[T]he Constitution does not forbid a State or city, pursuant to democratic processes, from expressing a preference for normal childbirth.' Webster v. Reproductive Health Services, 492 U. S., at 511 (opinion of the Court) (quoting Poelker v. Doe, 432 U. S. 519, 521 (1977)). It follows that States are free to enact laws to provide a reasonable framework for a woman to make a decision that has such profound and lasting meaning. This, too, we find consistent with Roe's central premises, and indeed the inevitable consequence of our holding that the State has an interest in protecting the life of the unborn.

We reject the trimester framework, which we do not consider to be part of the essential holding of Roe. See Webster v. Reproductive Health Services, supra, at 518 (opinion of Rehnquist, C. J.); id., at 529 (O'Connor, J., concurring in part and concurring in judgment) (describing the trimester framework as problematic). Measures aimed at ensuring that a woman's choice contemplates the consequences for the fetus do not necessarily interfere with the right recognized in Roe, although those measures have been found to be inconsistent with the rigid trimester framework announced in that case. A logical reading of the central holding in Roe itself, and a necessary reconciliation of the liberty of the woman and the interest of the State in promoting prenatal life, require, in our view, that we abandon the trimes- ter framework as a rigid prohibition on all previability regulation aimed at the protection of fetal life. The trimester framework suffers from these basic flaws: in its formulation it misconceives the nature of the pregnant woman's interest; and in practice it undervalues the State's interest in potential life, as recognized in Roe. As our jurisprudence relating to all liberties save perhaps abortion has recognized, not every law which makes a right more difficult to exercise is, ipso facto, an infringement of that right. An example clarifies the point. We have held that not every ballot access limitation amounts to an infringement of the right to vote. Rather, the States are granted substantial flexibility in establishing the framework within which voters choose the candidates for whom they wish to vote. Anderson v. Celebrezze, 460 U. S. 780, 788 (1983); Norman v. Reed, 502 U. S. ___ (1992).

The abortion right is similar. Numerous forms of state regulation might have the incidental effect of increasing the cost or decreasing the availability of medical care, whether for abortion or any other medical procedure. The fact that a law which serves a valid purpose, one not designed to strike at the right itself, has the incidental effect of making it more difficult or more expensive to procure an abortion cannot be enough to invalidate it. Only where state regulation imposes an undue burden on a woman's ability to make this decision does the power of the State reach into the heart of the liberty protected by the Due Process Clause. See Hodgson v. Minnesota, 497 U.S. 417, 458-459 (1990) (O'Connor, J., concurring in part and concurring in judgment in part); Ohio v. Akron Center for Reproductive Health, 497 U. S. 502, --- (1990) (Akron II) (opinion of Kennedy, J.) Webster v. Reproductive Health Services, supra, at 530 (O'Connor, J., concurring in part and concurring in judgment); Thornburgh v. American College of Obstetricians and Gynecologists, 476 U. S., at 828 (O'Connor, J., dissenting); Simopoulos v. Virginia, 462 U. S. 506, 520 (1983) (O'Connor, J., concurring in part and concurring in judgment); Planned Parenthood Assn. of Kansas City v. Ashcroft, 462 U. S. 476, 505 (1983) (O'Connor, J., concurring in judgment in part and dissenting in part); Akron I, 462 U.S., at 464 (O'Connor, J., joined by White and Rehnquist, JJ., dissenting); Bellotti v. Baird, 428 U.S. 132, 147 (1976) (Bellotti I).

/* This statement tends to avoid the fact that brain surgery, which is life threatening and far more chancy that an abortion does not have:

(1) Spousal notification requirements;

(2) 24 hour cooling off periods;

(3) special laws requiring information for the patient to be presented, etc.

Immediately after Roe (and as the opinion will state in the next sections) many states required extraordinary and burdensome requirements to make abortions legal but the Court struck this down. This new "re-affirmance" of the central principles of Roe is thus actually a significant retreat, allowing a great deal more "back door" regulation of abortions within the time fram when Roe provides for abortions on demand. */

For the most part, the Court's early abortion cases adhered to this view. In Maher v. Roe, 432 U.S. 464, 473-474 (1977), the Court explained: Roe did not declare an unqualified `constitutional right to an abortion,' as the District Court seemed to think. Rather, the right protects the woman from unduly burdensome interference with her freedom to decide whether to terminate her pregnancy. See also Doe v. Bolton, 410 U. S. 179, 198 (1973) ( [T]he interposition of the hospital abortion committee is unduly restrictive of the patient's rights); Bellotti I, supra, at 147 (State may not impose undue burdens upon a minor capable of giving an informed consent); Harris v. McRae, 448 U. S. 297, 314 (1980) (citing Maher, supra). Cf. Carey v. Population Services International, 431 U. S., at 688 ( [T]he same test must be applied to state regulations that burden an individual's right to decide to prevent conception or terminate pregnancy by substantially limiting access to the means of effectuating that decision as is applied to state statutes that prohibit the decision entirely).

These considerations of the nature of the abortion right illustrate that it is an overstatement to describe it as a right to decide whether to have an abortion without interference from the State, Planned Parenthood of Central Mo. v. Danforth, 428 U. S. 52, 61 (1976). All abortion regulations interfere to some degree with a woman's ability to decide whether to terminate her pregnancy. It is, as a consequence, not surprising that despite the protestations contained in the original Roe opinion to the effect that the Court was not recognizing an absolute right, 410 U. S., at 154-155, the Court's experience applying the trimester framework has led to the striking down of some abortion regulations which in no real sense deprived women of the ultimate decision. Those decisions went too far because the right recognized by Roe is a right to be free from unwarranted governmental intrusion into matters so fundamentally affecting a person as the deci sion whether to bear or beget a child. Eisenstadt v. Baird, 405 U. S., at 453. Not all governmental intrusion is of necessity unwarranted; and that brings us to the other basic flaw in the trimester framework: even in Roe's terms, in practice it undervalues the State's interest in the potential life within the woman.

Roe v. Wade was express in its recognition of the State's important and legitimate interest[s] in preserving and protecting the health of the pregnant woman [and] in protecting the potentiali- ty of human life. 410 U. S., at 162. The trimester framework, however, does not fulfill Roe's own promise that the State has an interest in protecting fetal life or potential life. Roe began the contradiction by using the trimester framework to forbid any regulation of abortion designed to advance that interest before viability. Id., at 163. Before viability, Roe and subsequent cases treat all governmental attempts to influence a woman's decision on behalf of the potential life within her as unwarranted. This treatment is, in our judgment, incompatible with the recognition that there is a substantial state interest in potential life throughout pregnancy. Cf. Webster, 492 U. S., at 519 (opinion of Rehnquist, C. J.); Akron I, supra, at 461 (O'Connor, J., dissenting).

The very notion that the State has a substantial interest in potential life leads to the conclusion that not all regulations must be deemed unwarranted. Not all burdens on the right to decide whether to terminate a pregnancy will be undue. In our view, the undue burden standard is the appropriate means of reconciling the State's interest with the woman's constitutionally protected liberty.

The concept of an undue burden has been utilized by the Court as well as individual members of the Court, including two of us, in ways that could be considered inconsistent. See, e.g., Hodgson v. Minnesota, 497 U. S., at --- (O'Connor, J., concurring in part and concurring in judgment); Akron II, 497 U. S., at --- (opinion of Kennedy, J.); Thornburgh v. American College of Obstetricians and Gynecologists, 476 U. S., at 828-829 (O'Connor, J., dissenting); Akron I, supra, at 461-466 (O'Connor, J., dissenting); Harris v. McRae, supra, at 314; Maher v. Roe, supra, at 473; Beal v. Doe, 432 U. S. 438, 446 (1977); Bellotti I, supra, at 147. Because we set forth a standard of general application to which we intend to adhere, it is important to clarify what is meant by an undue burden.

A finding of an undue burden is a shorthand for the conclusion that a state regulation has the purpose or effect of placing a substantial obstacle in the path of a woman seeking an abortion of a nonviable fetus. A statute with this purpose is invalid because the means chosen by the State to further the interest in potential life must be calculated to inform the woman's free choice, not hinder it. And a statute which, while furthering the interest in potential life or some other valid state interest, has the effect of placing a substantial obstacle in the path of a woman's choice cannot be considered a permissible means of serving its legitimate ends. To the extent that the opinions of the Court or of individual Justices use the undue burden standard in a manner that is inconsistent with this analysis, we set out what in our view should be the controlling standard. Cf. McCleskey v. Zant, 499 U. S. ---, ---

(1991) (slip op., at 20) (attempting to define the doctrine of abuse of the writ with more precision after acknowledging tension among earlier cases). In our considered judgment, an undue burden is an unconstitutional burden. See Akron II, supra, at --- (opinion of Kennedy, J.). Understood another way, we answer the question, left open in previous opinions discussing the undue burden formulation, whether a law designed to further the State's interest in fetal life which imposes an undue burden on the woman's decision before fetal viability could be constitutional. See, e.g., Akron I, supra, at 462-463 (O'Connor, J., dissenting). The answer is no.

Some guiding principles should emerge. What is at stake is the woman's right to make the ultimate decision, not a right to be insulated from all others in doing so. Regulations which do no more than create a structural mechanism by which the State, or the parent or guardian of a minor, may express profound respect for the life of the unborn are permitted, if they are not a substan- tial obstacle to the woman's exercise of the right to choose. See infra, at ___-___ (addressing Pennsylvania's parental consent requirement). Unless it has that effect on her right of choice, a state measure designed to persuade her to choose childbirth over abortion will be upheld if reasonably related to that goal. Regulations designed to foster the health of a woman seeking an abortion are valid if they do not constitute an undue burden.

Even when jurists reason from shared premises, some disagreement is inevitable. Compare Hodgson, 497 U. S., at ------- (opinion of Kennedy, J.) with id., at ------- (O'Connor, J., concurring in part and concurring in judgment in part). That is to be expected in the application of any legal standard which must accommodate life's complexity. We do not expect it to be otherwise with respect to the undue burden standard. We give this summary:

(a) To protect the central right recognized by Roe v. Wade while at the same time accommodating the State's profound interest in potential life, we will employ the undue burden analysis as explained in this opinion. An undue burden exists, and therefore a provision of law is invalid, if its purpose or effect is to place a substantial obstacle in the path of a woman seeking an abortion before the fetus attains viability.

(b) We reject the rigid trimester framework of Roe v. Wade. To promote the State's profound interest in potential life, throughout pregnancy the State may take measures to ensure that the woman's choice is informed, and measures designed to advance this interest will not be invalidated as long as their purpose is to persuade the woman to choose childbirth over abortion. These measures must not be an undue burden on the right.

(c) As with any medical procedure, the State may enact regulations to further the health or safety of a woman seeking an abortion. Unnecessary health regulations that have the purpose or effect of presenting a substantial obstacle to a woman seeking an abortion impose an undue burden on the right.

/* This begs the question. If critical brain surgery is not singled out for special restriction, then the question becomes one of intepreting intent. Placing even simple recordkeeping requirements on operations or seemingly innocuous waiting periods may not seem greatly burdensome, but do in fact appear to be quite difficult to reconcile with the fact that JUST abortion is chosen for such regulations. */

(d) Our adoption of the undue burden analysis does not disturb the central holding of Roe v. Wade, and we reaffirm that holding. Regardless of whether exceptions are made for particular circumstances, a State may not prohibit any woman from making the ultimate decision to terminate her pregnancy before viability.

(e) We also reaffirm Roe's holding that subsequent to viability, the State in promoting its interest in the potentiality of human life may, if it chooses, regulate, and even proscribe, abortion except where it is necessary, in appropriate medical judgment, for the preservation of the life or health of the mother. Roe v. Wade, 410 U. S., at 164-165.

These principles control our assessment of the Pennsylvania statute, and we now turn to the issue of the validity of its challenged provisions.

V

The Court of Appeals applied what it believed to be the undue burden standard and upheld each of the provisions except for the husband notification requirement. We agree generally with this conclusion, but refine the undue burden analysis in accordance with the principles articulated above. We now consider the separate statutory sections at issue.

A

Because it is central to the operation of various other requirements, we begin with the statute's definition of medical emergency. Under the statute, a medical emergency is

[t]hat condition which, on the basis of the physician's good faith clinical judgment, so complicates the medical condition of a pregnant woman as to necessitate the immediate abortion of her pregnancy to avert her death or for which a delay will create serious risk of substantial and irreversible impairment of a major bodily function. 18 Pa. Cons. Stat. (1990). 3203.

Petitioners argue that the definition is too narrow, contending that it forecloses the possibility of an immediate abortion despite some significant health risks. If the contention were correct, we would be required to invalidate the restrictive operation of the provision, for the essential holding of Roe forbids a State from interfering with a woman's choice to undergo an abortion procedure if continuing her pregnancy would constitute a threat to her health. 410 U. S., at 164. See also Harris v. McRae, 448 U. S., at 316.

The District Court found that there were three serious conditions which would not be covered by the statute: preeclampsia, inevitable abortion, and premature ruptured membrane. 744 F. Supp., at 1378. Yet, as the Court of Appeals observed, 947 F.2d, at 700-701, it is undisputed that under some circumstances each of these conditions could lead to an illness with substantial and irreversible consequences. While the definition could be interpreted in an unconstitutional manner, the Court of Appeals construed the phrase serious risk to include those circumstances. Id., at 701. It stated: we read the medical emergency exception as intended by the Pennsylvania legislature to assure that compliance with its abortion regulations would not in any way pose a significant threat to the life or health of a woman. Ibid. As we said in Brockett v. Spokane Arcades, Inc., 472 U. S. 491, 499-500 (1985): Normally, . . . we defer to the construction of a state statute given it by the lower federal courts. Indeed, we have said that we will defer to lower court interpretations of state law unless they amount to plain error. Palmer v. Hoffman, 318 U. S. 109, 118 (1943). This `reflect[s] our belief that district courts and courts of appeals are better schooled in and more able to interpret the laws of their respective States.' Frisby v. Schultz, 487 U. S. 474, 482 (1988) (citation omitted). We adhere to that course today, and conclude that, as construed by the Court of Appeals, the medical emergency definition imposes no undue burden on a woman's abortion right.

/* The "we will assume that they will re-write the statute through interpreting it" rule in which an invalid regulation is upheld due to, in this case, hoped constructions of the law. Or, it is a notice to the state that if it wants the law to be enforceable that the courts must narrow the scope of what the legislature intended. */

B

We next consider the informed consent requirement. 18 Pa. Cons. Stat. Ann. 3205. Except in a medical emergency, the statute requires that at least 24 hours before performing an abortion a physician inform the woman of the nature of the procedure, the health risks of the abortion and of childbirth, and the probable gestational age of the unborn child. The physician or a qualified nonphysician must inform the woman of the availability of printed materials published by the State describing the fetus and providing information about medical assistance for childbirth, information about child support from the father, and a list of agencies which provide adoption and other services as alternatives to abortion. An abortion may not be performed unless the woman certifies in writing that she has been informed of the availability of these printed materials and has been provided them if she chooses to view them.

Our prior decisions establish that as with any medical procedure, the State may require a woman to give her written informed consent to an abortion. See Planned Parenthood of Central Mo. v. Danforth, 428 U. S., at 67. In this respect, the statute is unexceptional. Petitioners challenge the statute's definition of informed consent because it includes the provision of specific information by the doctor and the mandatory 24-hour waiting period. The conclusions reached by a majority of the Justices in the separate opinions filed today and the undue burden standard adopted in this opinion require us to overrule in part some of the Court's past decisions, decisions driven by the trimester framework's prohibition of all previability regulations designed to further the State's interest in fetal life.