concurring in part and concurring in the judgment.
I concur in Parts Í, II-A, II-B, and II-C of the Court’s opinion.
I
Nothing in the record before us or the opinions below indicates that subsections 1(1) and 1(2) of the preamble to Missouri’s abortion regulation statute will affect a woman’s decision to have an abortion. Justice Stevens, following appellees, see Brief for Appellees 22, suggests that the preamble may also “interfer[e] with contraceptive choices,” post, at 564, because certain contraceptive devices act on a female ovum after it has been fertilized by a male sperm. The Missouri Act defines “conception” as “the fertilization of the ovum of a female by a sperm of a male,” Mo. Rev. Stat. § 188.015(3) (1986), and invests “unborn children” with “pro-tectable interests in life, health, and well-being,” § 1.205.1(2), from “the moment of conception . . . .” § 1.205.3. Justice Stevens asserts that any possible interference with a woman’s right to use such postfertilization contraceptive devices would be unconstitutional under Griswold v. Connecticut, 381 U. S. 479 (1965), and our subsequent contraception cases. Post, at 564-566. Similarly, certain amici suggest that the Missouri Act’s preamble may prohibit the developing technology of in vitro fertilization, a technique used to aid couples otherwise unable to bear children in which a number of ova are removed from the woman and fertilized by male sperm. This process often produces excess fertilized ova (“unborn children” under the Missouri Act’s definition) that are discarded rather than reinserted into the woman’s uterus. Brief for Association of Reproductive Health Pro*523fessionals et al. as Amici Curiae 38. It may be correct that the use of postfertilization contraceptive devices is constitutionally protected by Griswold and its progeny, but, as with a woman’s abortion decision, nothing in the record or the opinions below indicates that the preamble will affect a woman’s decision to practice contraception. For that matter, nothing in appellees’ original complaint, App. 8-21, or their motion in limine to limit testimony and evidence on their challenge to the preamble, id., at 57-59, indicates that appellees sought to enjoin potential violations of Griswold. Neither is there any indication of the possibility that the preamble might be applied to prohibit the performance of in vitro fertilization. I agree with the Court, therefore, that all of these intimations of unconstitutionality are simply too hypothetical to support the use of declaratory judgment procedures and in-junctive remedies in this case.
Similarly, it seems to me to follow directly from our previous decisions concerning state or federal funding of abortions, Harris v. McRae, 448 U. S. 297 (1980), Maher v. Roe, 432 U. S. 464 (1977), and Poelker v. Doe, 432 U. S. 519 (1977), that appellees’ facial challenge to the constitutionality of Missouri’s ban on the utilization of public facilities and the participation of public employees in the performance of abortions not necessary to save the life of the mother, Mo. Rev. Stat. §§ 188.210, 188.215 (1986), cannot succeed. Given Missouri’s definition of “public facility” as “any public institution, public facility, public equipment, or any physical asset owned, leased, or controlled by this state or any agency or political subdivisions thereof,” § 188.200(2), there may be conceivable applications of the ban on the use of public facilities that would be unconstitutional. Appellees and amici suggest that the State could try to enforce the ban against private hospitals using public water and sewage lines, or against private hospitals leasing state-owned equipment or state land. See Brief for Appellees 49-50; Brief for National Association of Public Hospitals as Amicus Curiae *5249-12. Whether some or all of these or other applications of § 188.215 would be constitutional need not be decided here. Maher, Poelker, and McRae stand for the proposition that some quite straightforward applications of the Missouri ban on the use of public facilities for performing abortions would be constitutional and that is enough to defeat appellees’ assertion that the ban is facially unconstitutional. “A facial challenge to a legislative Act is, of course, the most difficult challenge to mount successfully, since the challenger must establish that no set of circumstances exists under which the Act would be valid. The fact that the [relevant statute] might operate unconstitutionally under some conceivable set of circumstances is insufficient to render it wholly invalid, since we have not recognized an ‘overbreadth’ doctrine outside the limited context of the First Amendment.” United States v. Salerno, 481 U. S. 739, 745 (1987).
I also agree with the Court that, under the interpretation of § 188.205 urged by the State and adopted by the Court, there is no longer a case or controversy before us over the constitutionality of that provision. I would note, however, that this interpretation of § 188.205 is not binding on the Supreme Court of Missouri which has the final word on the meaning of that State’s statutes. Virginia v. American Booksellers Assn., Inc., 484 U. S. 383, 395 (1988); O’Brien v. Skinner, 414 U. S. 524, 531 (1974). Should it happen that § 188.205, as ultimately interpreted by the Missouri Supreme Court, does prohibit publicly employed health professionals from giving specific medical advice to pregnant women, “the vacation and dismissal of the complaint that has become moot ‘clears the path for future relitigation of the issues between the parties,’ should subsequent events rekindle their controversy.” Deakins v. Monaghan, 484 U. S. 193, 201, n. 5 (1988), quoting United States v. Munsingwear, Inc., 340 U. S. 36, 40 (1950). Unless such events make their appearance and give rise to relitigation, I agree that we and all federal *525courts are without jurisdiction to hear the merits of this moot dispute.
II
In its interpretation of Missouri’s “determination of viability” provision, Mo. Rev. Stat. §188.029 (1986), see ante, at 513-521, the plurality has proceeded in a manner unnecessary to deciding the question at hand. I agree with the plurality that it was plain error for the Court of Appeals to interpret the second sentence of § 188.029 as meaning that “doctors must perform tests to find gestational age, fetal weight and lung maturity.” 851 F. 2d 1071, 1075, n. 5 (CA8 1988) (emphasis in original). When read together with the first sentence of § 188.029 — which requires a physician to “determine if the unborn child is viable by using and exercising that degree of care, skill, and proficiency commonly exercised by the ordinary skillful, careful, and prudent physician engaged in similar practice under the same or similar conditions” — it would be contradictory nonsense to read the second sentence as requiring a physician to perform viability examinations and tests in situations where it would be careless and imprudent to do so. The plurality is quite correct: “the viability-testing provision makes sense only if the second sentence is read to require only those tests that are useful to making subsidiary findings as to viability,” ante, at 514, and, I would add, only those examinations and tests that it would not be imprudent or careless to perform in the particular medical situation before the physician.
Unlike the plurality, I do not understand these viability testing requirements to conflict with any of the Court’s past decisions concerning state regulation of abortion. Therefore, there is no necessity to accept the State’s invitation to reexamine the constitutional validity of Roe v. Wade, 410 U. S. 113 (1973). Where there is no need to decide a constitutional question, it is a venerable principle of this Court’s adjudicatory processes not to do so, for “[t]he Court will not ‘anticipate a question of constitutional law in advance of the *526necessity of deciding it.’” Ashwander v. TVA, 297 U. S. 288, 346 (1936) (Brandeis, J., concurring), quoting Liverpool, New York & Philadelphia S. S. Co. v. Commissioners of Emigration, 113 U. S. 33, 39 (1885). Neither will it generally “formulate a rule of constitutional law broader than is required by the precise facts to which it is to be applied.” 297 U. S., at 347. Quite simply, “[i]t is not the habit of the court to decide questions of a constitutional nature unless absolutely necessary to a decision of the case.” Burton v. United States, 196 U. S. 283, 295 (1905). The Court today has accepted the State’s every interpretation of its abortion statute and has upheld, under our existing precedents, every provision of that statute which is properly before us. Precisely for this reason reconsideration of Roe falls not into any “good-cause exception” to this “fundamental rule of judicial restraint . . . .” Three Affiliated Tribes of Fort Berthold Reservation v. Wold Engineering, P. C., 467 U. S. 138, 157 (1984). See post, at 532-533 (Scalia, J., concurring in part and concurring in judgment). When the constitutional invalidity of a State’s abortion statute actually turns on the constitutional validity of Roe v. Wade, there will be time enough to reexamine Roe. And to do so carefully.
In assessing § 188.029 it is especially important to recognize that appellees did not appeal the District Court’s ruling that the first sentence of § 188.029 is constitutional. 662 F. Supp. 407, 420-422 (WD Mo. 1987). There is, accordingly, no dispute between the parties before us over the constitutionality of the “presumption of viability at 20 weeks,” ante, at 515, created by the first sentence of § 188.029. If anything might arguably conflict with the Court’s previous decisions concerning the determination of viability, I would think it is the introduction of this presumption. The plurality, see ante, at 515, refers to a passage from Planned Parenthood of Central Mo. v. Danforth, 428 U. S. 52, 64 (1976): “The time when viability is achieved may vary with each pregnancy, and the determination of whether a particular fetus is viable is, and must *527be, a matter for the judgment of the responsible attending physician.” The 20-week presumption of viability in the first sentence of §188.029, it could be argued (though, I would think, unsuccessfully), restricts “the judgment of the responsible attending physician,” by imposing on that physician the burden of overcoming the presumption. This presumption may be a “superimpos[ition] [of] state regulation on the medical determination whether a particular fetus is viable,” ante, at 517, but, if so, it is a restriction on the physician’s judgment that is not before us. As the plurality properly interprets the second sentence of § 188.029, it does nothing more than delineate means by which the unchallenged 20-week presumption of viability may be overcome if those means are useful in doing so and can be prudently employed. Contrary to the plurality’s suggestion, see ante, at 517, the District Court did not think the second sentence of § 188.029 unconstitutional for this reason. Rather, both the District Court and the Court of Appeals thought the second sentence to be unconstitutional precisely because they interpreted that sentence to impose state regulation on the determination of viability that it does not impose.
Appellees suggest that the interpretation of § 188.029 urged by the State may “virtually eliminat[e] the constitutional issue in this case.” Brief for Appellees 30. Appellees therefore propose that we should abstain from deciding that provision’s constitutionality “in order to allow the state courts to render the saving construction the State has proposed.” Ibid. Where the lower court has so clearly fallen into error I do not think abstention is necessary or prudent. Accordingly, I consider the constitutionality of the second sentence of §188.029, as interpreted by the State, to determine whether the constitutional issue is actually eliminated.
I do not think the second sentence of § 188.029, as interpreted by the Court, imposes a degree of state regulation on the medical determination of viability that in any way conflicts with prior decisions of this Court. As the plurality *528recognizes, the requirement that, where not imprudent, physicians perform examinations and tests useful to making subsidiary findings to determine viability “promotes] the State’s interest in potential human life rather than in maternal health.” Ante, at 515. No decision of this Court has held that the State may not directly promote its interest in potential life when viability is possible. Quite the contrary. In Thornburgh v. American College of Obstetricians and Gynecologists, 476 U. S. 747 (1986), the Court considered a constitutional challenge to a Pennsylvania statute requiring that a second physician be present during an abortion performed “when viability is possible.” Id., at 769-770. For guidance, the Court looked to the earlier decision in Planned Parenthood Assn. of Kansas City, Mo., Inc. v. Ashcroft, 462 U. S. 476 (1983), upholding a Missouri statute requiring the presence of a second physician during an abortion performed after viability. Id., at 482-486 (opinion of Powell, J.); id., at 505 (O’Connor, J., concurring in judgment in part and dissenting in part). The Thornburgh majority struck down the Pennsylvania statute merely because the statute had no exception for emergency situations and not because it found a constitutional difference between the State’s promotion of its interest in potential life when viability is possible and when viability is certain. 476 U. S., at 770-771. Despite the clear recognition by the Thornburgh majority that the Pennsylvania and Missouri statutes differed in this respect, there is no hint in the opinion of the Thornburgh Court that the State’s interest in potential life differs depending on whether it seeks to further that interest postviability or when viability is possible. Thus, all nine Members of the Thornburgh Court appear to have agreed that it is not constitutionally impermissible for the State to enact regulations designed to protect the State’s interest in potential life when viability is possible. See id., at 811 (White, J., dissenting); id., at 832 (O’Connor, J., dissenting). That is exactly what Missouri has done in § 188.029.
*529Similarly, the basis for reliance by the District Court and the Court of Appeals below on Colautti v. Franklin, 439 U. S. 379 (1979), disappears when § 188.029 is properly interpreted. In Colautti, the Court observed:
“Because this point [of viability] may differ with each pregnancy, neither the legislature nor the courts may proclaim one of the elements entering into the ascertainment of viability — be it weeks of gestation or fetal weight or any other single factor — as the determinant of when the State has a compelling interest in the life or health of the fetus. Viability is the critical point.” Id,., at 388-389.
The courts below, on the interpretation of § 188.029 rejected here, found the second sentence of that provision at odds with this passage from Colautti. See 851 F. 2d, at 1074; 662 F. Supp., at 423. On this Court’s interpretation of § 188.029 it is clear that Missouri has not substituted any of the “elements entering into the ascertainment of viability” as “the determinant of when the State has a compelling interest in the life or health of the fetus.” All the second sentence of § 188.029 does is to require, when not imprudent, the performance of “those tests that are useful to making subsidiary findings as to viability.” Ante, at 514 (emphasis added). Thus, consistent with Colautti, viability remains the “critical point” under § 188.029.
Finally, and rather halfheartedly, the plurality suggests that the marginal increase in the cost of an abortion created by Missouri’s viability testing provision may make § 188.029, even as interpreted, suspect under this Court’s decision in Akron v. Akron Center for Reproductive Health, Inc., 462 U. S. 416, 434-439 (1983), striking down a second-trimester hospitalization requirement. See ante, at 517. I dissented from the Court’s opinion in Akron because it was my view that, even apart from Roe’s trimester framework which I continue to consider problematic, see Thornburgh, supra, at *530828 (dissenting opinion), the Akron majority had distorted and misapplied its own standard for evaluating state regulation of abortion which the Court had applied with fair consistency in the past: that, previability, “a regulation imposed on a lawful abortion is not unconstitutional unless it unduly burdens the right to seek an abortion.” Akron, supra, at 453 (dissenting opinion) (internal quotations omitted).
It is clear to me that requiring the performance of examinations and tests useful to determining whether a fetus is viable, when viability is possible, and when it would not be medically imprudent to do so, does not impose an undue burden on a woman’s abortion decision. On this ground alone I would reject the suggestion that § 188.029 as interpreted is unconstitutional. More to the point, however, just as I see no conflict between § 188.029 and Colautti or any decision of this Court concerning a State’s ability to give effect to its interest in potential life, I see no conflict between § 188.029 and the Court’s opinion in Akron. The second-trimester hospitalization requirement struck down in Akron imposed, in the majority’s view, “a heavy, and unnecessary, burden,” 462 U. S., at 438, more than doubling the cost of “women’s access to a relatively inexpensive, otherwise accessible, and safe abortion procedure.” Ibid.; see also id., at 434. By contrast, the cost of examinations and tests that could usefully and prudently be performed when a woman is 20-24 weeks pregnant to determine whether the fetus is viable would only marginally, if at all, increase the cost of an abortion. See Brief for American Association of Prolife Obstetricians and Gynecologists et al. as Amici Curiae 3 (“At twenty weeks gestation, an ultrasound examination to determine gestational age is standard medical practice. It is routinely provided by the plaintiff clinics. An ultrasound examination can effectively provide all three designated findings of sec. 188.029”); id., at 22 (“A finding of fetal weight can be obtained from the same ultrasound test used to determine gestational age”); id., at 25 (“There are a number of different *531methods in standard medical practice to determine fetal lung maturity at twenty or more weeks gestation. The most simple and most obvious is by inference. It is well known that fetal lungs do not mature until 33-34 weeks gestation. . . . If an assessment of the gestational age indicates that the child is less than thirty-three weeks, a general finding can be made that the fetal lungs are not mature. This finding can then be used by the physician in making his determination of viability under section 188.029”); cf. Brief for American Medical Association et al. as Amici Curiae 42 (no suggestion that fetal weight and gestational age cannot be determined from the same sonogram); id., at 43 (another clinical test for gestational age and, by inference, fetal weight and lung maturity, is an accurate report of the last menstrual period), citing Smith, Frey, & Johnson, Assessing Gestational Age, 33 Am. Fam. Physician 215, 219-220 (1986).
Moreover, the examinations and tests required by § 188.029 are to be performed when viability is possible. This feature of § 188.029 distinguishes it from the second-trimester hospitalization requirement struck down by the Akron majority. As the Court recognized in Thornburgh, the State’s compelling interest in potential life postviability renders its interest in determining the critical point of viability equally compelling. See supra, at 527-528. Under the Court’s precedents, the same cannot be said for the Akron second-trimester hospitalization requirement. As I understand the Court’s opinion in Akron, therefore, the plurality’s suggestion today that Akron casts doubt on the validity of §188.029, even as the Court has interpreted it, is without foundation and cannot provide a basis for reevaluating Roe. Accordingly, because the Court of Appeals misinterpreted §188.029, and because, properly interpreted, § 188.029 is not inconsistent with any of this Court’s prior precedents, I would reverse the decision of the Court of Appeals.
In sum, I concur in Parts I, II-A, II-B, and II-C of the Court’s opinion and concur in the judgment as to Part II-D.