opinion: MICHAEL H. et al. v. GERALD D.
  APPEAL FROM THE COURT OF APPEAL OF CALIFORNIA, SECOND APPELLATE DISTRICT
  No. 87-746.
  Argued October 11, 1988
  Decided June 15, 1989
  Robert A. W. Boraks argued the cause for appellants. With him on the briefs for appellant Michael H. were George Kaufmann, Ronald K. Henry, Paul R. Taskier, and Joel S. Aaronson. Leslie Ellen Shear filed briefs for appellant Victoria D.
  Larry M. Hoffman argued the cause for appellee. With him on the brief was Glen H. Schwartz.
  Michael L. Oddenino filed a brief for the National Council for Children’s Rights as amicus curiae urging reversal.
  Paul Hoffman, Joan Howarth, John A. Powell, Helen Hershkoff, Steven R. Shapiro, and Isabelle Katz Pinzler filed a brief for the American Civil Liberties Union Foundation et al. as amici curiae.
  Justice Scalia
  announced the judgment of the Court and delivered an opinion, in which The Chief Justice joins, and in all but footnote 6 of which Justice O’Connor and Justice Kennedy join.
  Under California law, a child born to a married woman living with her husband is presumed to be a child of the marriage. Cal. Evid. Code Ann. § 621 (West Supp. 1989). The presumption of legitimacy may be rebutted only by the husband or wife, and then only in limited circumstances. Ibid. The instant appeal presents the claim that this presumption infringes upon the due process rights of a man who wishes to establish his paternity of a child born to the wife of another man, and the claim that it infringes upon the constitutional right of the child to maintain a relationship with her natural father.
  I
  The facts of this case are, we must hope, extraordinary. On May 9, 1976, in Las Vegas, Nevada, Carole D., an international model, and Gerald D., a top executive in a French oil company, were married. The couple established a home in Playa del Rey, California, in which they resided as husband and wife when one or the other was not out of the country on business. In the summer of 1978, Carole became involved in an adulterous affair with a neighbor, Michael H. In September 1980, she conceived a child, Victoria D., who was born on May 11, 1981. Gerald was listed as father on the birth certificate and has always held Victoria out to the world as his daughter. Soon after delivery of the child, however, Carole informed Michael that she believed he might be the father.
  In the first three years of her life, Victoria remained always with Carole, but found herself within a variety of quasi-family units. In October 1981, Gerald moved to New York City to pursue his business interests, but Carole chose to remain in California. At the end of that month, Carole and Michael had blood tests of themselves and Victoria, which showed a 98.07% probability that Michael was Victoria’s father. In January 1982, Carole visited Michael in St. Thomas, where his primary business interests were based. There Michael held Victoria out as his child. In March, however, Carole left Michael and returned to California, where she took up residence with yet another man, Scott K. Later that spring, and again in the summer, Carole and Victoria spent time with Gerald in New York City, as well as on vacation in Europe. In the fall, they returned to Scott in California.
  In November 1982, rebuffed in his attempts to visit Victoria, Michael filed a filiation action in California Superior Court to establish his paternity and right to visitation. In March 1983, the court appointed an attorney and guardian ad litem to represent Victoria’s interests. Victoria then filed a cross-complaint asserting that if she had more than one psychological or defacto father, she was entitled to maintain her filial relationship, with all of the attendant rights, duties, and obligations, with both. In May 1983, Carole filed a motion for summary judgment. During this period, from March through July 1983, Carole was again living with Gerald in New York. In August, however, she returned to California, became involved once again with Michael, and instructed her attorneys to remove the summary judgment motion from the calendar.
  For the ensuing eight months, when Michael was not in St. Thomas he lived with Carole and Victoria in Carole’s apartment in Los Angeles and held Victoria out as his daughter. In April 1984, Carole and Michael signed a stipulation that Michael was Victoria’s natural father. Carole left Michael the next month, however, and instructed her attorneys not to file the stipulation. In June 1984, Carole reconciled with Gerald and joined him in New York, where they now live with Victoria and two other children since born into the marriage.
  In May 1984, Michael and Victoria, through her guardian ad litem, sought visitation rights for Michael pendente lite. To assist in determining whether visitation would be in Victoria’s best interests, the Superior Court appointed a psychologist to evaluate Victoria, Gerald, Michael, and Carole. The psychologist recommended that Carole retain sole custody, but that Michael be allowed continued contact with Victoria pursuant to a restricted visitation schedule. The court concurred and ordered that Michael be provided with limited visitation privileges pendente lite.
  On October 19, 1984, Gerald, who had intervened in the action, moved for summary judgment on the ground that under Cal. Evid. Code § 621 there were no triable issues of fact as to Victoria’s paternity. This law provides that “the issue of a wife cohabiting with her husband, who is not impotent or sterile, is conclusively presumed to be a child of the marriage.” Cal. Evid. Code Ann. § 621(a) (West Supp. 1989). The presumption may be rebutted by blood tests, but only if a motion for such tests is made, within two years from the date of the child’s birth, either by the husband or, if the natural father has filed an affidavit acknowledging paternity, by the wife. §§ 621(c) and (d).
  On January 28, 1985, having found that affidavits submitted by Carole and Gerald sufficed to demonstrate that the two were cohabiting at conception and birth and that Gerald was neither sterile nor impotent, the Superior Court granted Gerald’s motion for summary judgment, rejecting Michael’s and Victoria’s challenges to the constitutionality of §621. The court also denied their motions for continued visitation pending the appeal under Cal. Civ. Code §4601, which provides that a court may, in its discretion, grant “reasonable visitation rights ... to any . . . person having an interest in the welfare of the child.” Cal. Civ. Code Ann. §4601 (West Supp. 1989). It found that allowing such visitation would “violat[e] the intention of the Legislature by impugning the integrity of the family unit.” Supp. App. to Juris. Statement A-91.
  On appeal, Michael asserted, inter alia, that the Superior Court’s application of §621 had violated his procedural and substantive due process rights. Victoria also raised a due process challenge to the statute, seeking to preserve her de facto relationship with Michael as well as with Gerald. She contended, in addition, that as § 621 allows the husband and, at least to a limited extent, the mother, but not the child, to rebut the presumption of legitimacy, it violates the child’s right to equal protection. Finally, she asserted a right to continued visitation with Michael under §4601. After submission of briefs and a hearing, the California Court of Appeal affirmed the judgment of the Superior Court and upheld the constitutionality of the statute. 191 Cal. App. 3d 995, 236 Cal. Rptr. 810 (1987). It interpreted that judgment, moreover, as having denied permanent visitation rights under §4601, regarding that as the implication of the Superior Court’s reliance upon § 621 and upon an earlier California case, Vincent B. v. Joan R., 126 Cal. App. 3d 619, 179 Cal. Rptr. 9 (1981), appeal dism’d, 459 U. S. 807 (1982), which had held that once an assertion of biological paternity is “determined to be legally impossible” under § 621, visitation against the wishes of the mother should be denied under § 4601. 126 Cal. App. 3d, at 627-628, 179 Cal. Rptr., at 13.
  The Court of Appeal denied Michael’s and Victoria’s petitions for rehearing, and, on July 30, 1987, the California Supreme Court denied discretionary review. On February 29, 1988, we noted probable jurisdiction of the present appeal. 485 U. S. 903. Before us, Michael and Victoria both raise equal protection and due process challenges. We do not reach Michael’s equal protection claim, however, as it was neither raised nor passed upon below. See Bankers Life & Casualty Co. v. Crenshaw, 486 U. S. 71 (1988).
  ( — I I — I
  The California statute that is the subject of this litigation is, in substance, more than a century old. California Code of Civ. Proc. § 1962(5), enacted in 1872, provided that “[t]he issue of a wife cohabiting with her husband, who is not impotent, is indisputably presumed to be legitimate.” In 1955, the legislature amended the statute by adding the preface: “Notwithstanding any other provision of law.” 1955 Cal. Stats., ch. 948, p. 1835, §3. In 1965, when California’s Evidence Code was adopted, the statute was codified as § 621, with no substantive change except replacement of the word “indisputably” with “conclusively,” 1965 Cal. Stats., ch. 299, §2, pp. 1297, 1308. When California adopted the Uniform Parentage Act, 1975 Cal. Stats., ch. 1244, §11, pp. 3196-3201, codified at Cal. Civ. Code Ann. §7000 et seq. (West 1983), it amended §621 by replacing the word “legitimate” with the phrase “a child of the marriage” and by adding nonsterility to nonimpotence and cohabitation as a predicate for the presumption. 1975 Cal. Stats., ch. 1244, §13, p. 3202. In 1980, the legislature again amended the statute to provide the husband an opportunity to introduce blood-test evidence in rebuttal of the presumption, 1980 Cal. Stats., ch. 1310, p. 4433; and in 1981 amended it to provide the mother such an opportunity, 1981 Cal. Stats., ch. 1180, p. 4761. In their present form, the substantive provisions of the statute are as follows:
  “§ 621. Child of the marriage; notice of motion for blood tests
  “(a) Except as provided in subdivision (b), the issue of a wife cohabiting with her husband, who is not impotent or sterile, is conclusively presumed to be a child of the marriage.
  “(b) Notwithstanding the provisions of subdivision (a), if the court finds that the conclusions of all the experts, as disclosed by the evidence based upon blood tests performed pursuant to Chapter 2 (commencing with Section 890) of Division 7 are that the husband is not the father of the child, the question of paternity of the husband shall be resolved accordingly.
  “(c) The notice of motion for blood tests under subdivision (b) may be raised by the husband not later than two years from the child’s date of birth.
  “(d) The notice of motion for blood tests under subdivision (b) may be raised by the mother of the child not later than two years from the child’s date of birth if the child’s biological father has filed an affidavit with the court acknowledging paternity of the child.
  “(e) The provisions of subdivision (b) shall not apply to any case coming within the provisions of Section 7005 of the Civil Code [dealing with artificial insemination] or to any case in which the wife, with the consent of the husband, conceived by means of a surgical procedure.”
  Ill
  We address first the claims of Michael. At the outset, it is necessary to clarify what he sought and what he was denied. California law, like nature itself, makes no provision for dual fatherhood. Michael was seeking to be declared the father of Victoria. The immediate benefit he evidently sought to obtain from that status was visitation rights. See Cal. Civ. Code Ann. §4601 (West 1983) (parent has statutory right to visitation “unless it is shown that such visitation would be detrimental to the best interests of the child”). But if Michael were successful in being declared the father, other rights would follow — most importantly, the right to be considered as the parent who should have custody, Cal. Civ. Code Ann. § 4600 (West 1983), a status which “embrace[s] the sum of parental rights with respect to the rearing of a child, including the child’s care; the right to the child’s services and earnings; the right to direct the child’s activities; the right to make decisions regarding the control, education, and health of the child; and the right, as well as the duty, to prepare the child for additional obligations, which includes the teaching of moral standards, religious beliefs, and elements of good citizenship.” 4 California Family Law §60.02[l][b] (C. Markey ed. 1987) (footnotes omitted). All parental rights, including visitation, were automatically denied by denying Michael status as the father. While Cal. Civ. Code Ann. § 4601 places it within the discretionary power of a court to award visitation rights to a nonparent, the Superior Court here, affirmed by the Court of Appeal, held that California law denies visitation, against the wishes of the mother, to a putative father who has been prevented by § 621 from establishing his paternity. See 191 Cal. App. 3d, at 1013, 236 Cal. Rptr., at 821, citing Vincent B. v. Joan R., 126 Cal. App. 3d, at 627-628 179 Cal. Rptr., at 13.
  Michael raises two related challenges to the constitutionality of §621. First, he asserts that requirements of procedural due process prevent the State from terminating his liberty interest in his relationship with his child without affording him an opportunity to demonstrate his paternity in an evidentiary hearing. We believe this claim derives from a fundamental misconception of the nature of the California statute. While § 621 is phrased in terms of a presumption, that rule of evidence is the implementation of a substantive rule of law. California declares it to be, except in limited circumstances, irrelevant for paternity purposes whether a child conceived during, and born into, an existing marriage was begotten by someone other than the husband and had a prior relationship with him. As the Court of Appeal phrased it:
  “ ‘The conclusive presumption is actually a substantive rule of law based upon a determination by the Legislature as a matter of overriding social policy, that given a certain relationship between the husband and wife, the husband is to be held responsible for the child, and that the integrity of the family unit should not be impugned.’” 191 Cal. App. 3d, at 1005, 236 Cal. Rptr., at 816, quoting Vincent B. v. Joan R., supra, at 623, 179 Cal. Rptr., at 10.
  Of course the conclusive presumption not only expresses the State’s substantive policy but also furthers it, excluding inquiries into the child’s paternity that would be destructive of family integrity and privacy.
  This Court has struck down as illegitimate certain “irrebut-table presumptions.” See, e. g., Stanley v. Illinois, 405 U. S. 645 (1972); Vlandis v. Kline, 412 U. S. 441 (1973); Cleveland Board of Education v. LaFleur, 414 U. S. 632 (1974). Those holdings did not, however, rest upon procedural due process. A conclusive presumption does, of course, foreclose the person against whom it is invoked from demonstrating, in a particularized proceeding, that applying the presumption to him will in fact not further the lawful governmental policy the presumption is designed to effectuate. But the same can be said of any legal rule that establishes general classifications, whether framed in terms of a presumption or not. In this respect there is no difference between a rule which says that the marital husband shall be irrebuttably presumed to be the father, and a rule which says that the adulterous natural father shall not be recognized as the legal father. Both rules deny someone in Michael’s situation a hearing on whether, in the particular circumstances of his case, California’s policies would best be served by giving him parental rights. Thus, as many commentators have observed, see, e. g., Bezanson, Some Thoughts on the Emerging Irrebuttable Presumption Doctrine, 7 Ind. L. Rev. 644 (1974); Nowak, Realigning the Standards of Review Under the Equal Protection Guarantee-Prohibited, Neutral, and Permissive Classifications, 62 Geo. L. J. 1071, 1102-1106 (1974); Note, Irrebuttable Presumptions: An Illusory Analysis, 27 Stan. L. Rev. 449 (1975); Note, The Irrebuttable Presumption Doctrine in the Supreme Court, 87 Harv. L. Rev. 1534 (1974), our “irre-buttable presumption” cases must ultimately be analyzed as calling into question not the adequacy of procedures but— like our cases involving classifications framed in other terms, see, e. g., Craig v. Boren, 429 U. S. 190 (1976); Carrington v. Rash, 380 U. S. 89 (1965) — the adequacy of the “fit” between the classification and the policy that the classification serves. See LaFleur, supra, at 652 (Powell, J., concurring in result); Vlandis, supra, at 456-459 (White, J., concurring), 466-469 (Rehnquist, J., dissenting); Weinberger v. Salfi, 422 U. S. 749 (1975). We therefore reject Michael’s procedural due process challenge and proceed to his substantive claim.
  Michael contends as a matter of substantive due process that, because he has established a parental relationship with Victoria, protection of Gerald’s and Carole’s marital union is an insufficient state interest to support termination of that relationship. This argument is, of course, predicated on the assertion that Michael has a constitutionally protected liberty interest in his relationship with Victoria.
  It is an established part of our constitutional jurisprudence that the term “liberty” in the Due Process Clause extends beyond freedom from physical restraint. See, e. g., Pierce v. Society of Sisters, 268 U. S. 510 (1925); Meyer v. Nebraska, 262 U. S. 390 (1923). Without that core textual meaning as a limitation, defining the scope of the Due Process Clause “has at times been a treacherous field for this Court,” giving “reason for concern lest the only limits to . . . judicial intervention become the predilections of those who happen at the time to be Members of this Court.” Moore v. East Cleveland, 431 U. S. 494, 502 (1977). The need for restraint has been cogently expressed by Justice White:
  “That the Court has ample precedent for the creation of new constitutional rights should not lead it to repeat the process at will. The Judiciary, including this Court, is the most vulnerable and comes nearest to illegitimacy when it deals with judge-made constitutional law having little or no cognizable roots in the language or even the design of the Constitution. Realizing that the present construction of the Due Process Clause represents a major judicial gloss on its terms, as well as on the anticipation of the Framers . . . , the Court should be extremely reluctant to breathe still further substantive content into the Due Process Clause so as to strike down legislation adopted by a State or city to promote its welfare. Whenever the Judiciary does so, it unavoidably pre-empts for itself another part of the governance of the country without express constitutional authority.” Moore, supra, at 544 (dissenting opinion).
  In an attempt to limit and guide interpretation of the Clause, we have insisted not merely that the interest denominated as a “liberty” be “fundamental” (a concept that, in isolation, is hard to objectify), but also that it be an interest traditionally protected by our society. As we have put it, the Due Process Clause affords only those protections “so rooted in the traditions and conscience of our people as to be ranked as fundamental.” Snyder v. Massachusetts, 291 U. S. 97, 105 (1934) (Cardozo, J.). Our cases reflect “continual insistence upon respect for the teachings of history [and] solid recognition of the basic values that underlie our society. ...” Griswold v. Connecticut, 381 U. S. 479, 501 (1965) (Harlan, J., concurring in judgment).
  This insistence that the asserted liberty interest be rooted in history and tradition is evident, as elsewhere, in our cases according constitutional protection to certain parental rights. Michael reads the landmark case of Stanley v. Illinois, 405 U. S. 645 (1972), and the subsequent cases of Quilloin v. Walcott, 434 U. S. 246 (1978), Caban v. Mohammed, 441 U. S. 380 (1979), and Lehr v. Robertson, 463 U. S. 248 (1983), as establishing that a liberty interest is created by biological fatherhood plus an established parental relationship-factors that exist in the present case as well. We think that distorts the rationale of those cases. As we view them, they rest not upon such isolated factors but upon the historic respect — indeed, sanctity would not be too strong a term — traditionally accorded to the relationships that develop within the unitary family. See Stanley, supra, at 651; Quilloin, supra, at 254-255; Caban, supra, at 389; Lehr, supra, at 261. In Stanley, for example, we forbade the destruction of such a family when, upon the death of the mother, the State had sought to remove children from the custody of a father who had lived with and supported them and their mother for 18 years. As Justice Powell stated for the plurality in Moore v. East Cleveland, supra, at 503: “Our decisions establish that the Constitution protects the sanctity of the family precisely because the institution of the family is deeply rooted in this Nation’s history and tradition.”
  Thus, the legal issue in the present case reduces to whether the relationship between persons in the situation of Michael and Victoria has been treated as a protected family unit under the historic practices of our society, or whether on any other basis it has been accorded special protection. We think it impossible to find that it has. In fact, quite to the contrary, our traditions have protected the marital family (Gerald, Carole, and the child they acknowledge to be theirs) against the sort of claim Michael asserts.
  The presumption of legitimacy was a fundamental principle of the common law. H. Nicholas, Adulturine Bastardy 1 (1836). Traditionally, that presumption could be rebutted only by proof that a husband was incapable of procreation or had had no access to his wife during the relevant period. Id., at 9-10 (citing Bracton, De Legibus et Consuetudinibus Angliae, bk. i, ch. 9, p. 6; bk. ii, ch. 29, p. 63, ch. 32, p. 70 (1569)). As explained by Blackstone, nonaccess could only be proved “if the husband be out of the kingdom of England (or, as the law somewhat loosely phrases it, extra quatuor maria [beyond the four seas]) for above nine months. . . .” 1 Blackstone’s Commentaries 456 (J. Chitty ed. 1826). And, under the common law both in England and here, “neither husband nor wife [could] be a witness to prove access or nonaccess.” J. Schouler, Law of the Domestic Relations §225, p. 306 (3d ed. 1882); R. Graveson & F. Crane, A Century of Family Law: 1857-1957, p. 158 (1957). The primary policy rationale underlying the common law’s severe restrictions on rebuttal of the presumption appears to have been an aversion to declaring children illegitimate, see Schouler, supra, §225, at 306-307; M. Grossberg, Governing the Hearth 201 (1985), thereby depriving them of rights of inheritance and succession, 2 J. Kent, Commentaries on American Law *175, and likely making them wards of the state. A secondary policy concern was the interest in promoting the “peace and tranquillity of States and families,” Schouler, supra, §225, at 304, quoting Boullenois, Traité des Status, bk. 1, p. 62, a goal that is obviously impaired by facilitating suits against husband and wife asserting that their children are illegitimate. Even though, as bastardy laws became less harsh, “[j]udges in both [England and the United States] gradually widened the acceptable range of evidence that could be offered by spouses, and placed restraints on the 'four seas rule’ ...[,] the law retained a strong bias against ruling the children of married women illegitimate.” Grossberg, supra, at 202.
  We have found nothing in the older sources, nor in the older cases, addressing specifically the power of the natural father to assert parental rights over a child born into a woman’s existing marriage with another man. Since it is Michael’s burden to establish that such a power (at least where the natural father has established a relationship with the child) is so deeply embedded within our traditions as to be a fundamental right, the lack of evidence alone might defeat his case. But the evidence shows that even in modern times — when, as we have noted, the rigid protection of the marital family has in other respects been relaxed — the ability of a person in Michael’s position to claim paternity has not been generally acknowledged. For example, a 1957 annotation on the subject: “Who may dispute presumption of legitimacy of child conceived or born during wedlock,” 53 A. L. R. 2d 572, shows three States (including California) with statutes limiting standing to the husband or wife and their descendants, one State (Louisiana) with a statute limiting it to the husband, two States (Florida and Texas) with judicial decisions limiting standing to the husband, and two States (Illinois and New York) with judicial decisions denying standing even to the mother. Not a single decision is set forth specifically according standing to the natural father, and “express indications of the nonexistence of any . . . limitation” upon standing were found only “in a few jurisdictions.” Id., at 579.
  Moreover, even if it were clear that one in Michael’s position generally possesses, and has generally always possessed, standing to challenge the marital child’s legitimacy, that would still not establish Michael’s case. As noted earlier, what is at issue here is not entitlement to a state pronouncement that Victoria was begotten by Michael. It is no conceivable denial of constitutional right for a State to decline to declare facts unless some legal consequence hinges upon the requested declaration. What Michael asserts here is a right to have himself declared the natural father and thereby to obtain parental prerogatives What he must establish, therefore, is not that our society has traditionally allowed a natural father in his circumstances to establish paternity, but that it has traditionally accorded such a father parental rights, or at least has not traditionally denied them. Even if the law in all States had always been that the entire world could challenge the marital presumption and obtain a declaration as to who was the natural father, that would not advance Michael’s claim. Thus, it is ultimately irrelevant, even for purposes of determining carretil: social attitudes towards the alleged substantive right Michael asserts, that the present law in a number of States appears to allow the natural father — including the natural father who has not established a relationship with the child — the theoretical power to rebut the marital presumption, see Note, Rebutting the Marital Presumption: A Developed Relationship Test, SS Colum. L. Rev. 369, 373 (19SS). What counts is whether the States in fact award substantive parental rights to the natural father of a child conceived within, and born into, an extant marital union that wishes to embrace the child. We are not aware of a single case, old or new, that has done so. This is not the stuff of which fundamental rights qualifying as liberty interests are made.
  In Lehr v. Robertson, a case involving a natural father’s attempt to block his child’s adoption by the unwed mother’s new husband, we observed that “[t]he significance of the biological connection is that it offers the natural fathér an opportunity that no other male possesses to develop a relationship with his offspring,” 463 U. S., at 262, and we assumed that the Constitution might require some protection of that opportunity, id., at 262-265. Where, however, the child is born into an extant marital family, the natural father’s unique opportunity conflicts with the similarly unique opportunity of the husband of the marriage; and it is not unconstitutional for the State to give categorical preference to the latter. In Lehr we quoted approvingly from Justice Stewart’s dissent in Caban v. Mohammed, 441 U. S., at 397, to the effect that although “‘[i]n some circumstances the actual relationship between father and child may suffice to create in the unwed father parental interests comparable to those of the married father,”’ “‘the absence of a legal tie with the mother may in such circumstances appropriately place a limit on whatever substantive constitutional claims might otherwise exist.’” 463 U. S., at 260, n. 16. In accord with our traditions, a limit is also imposed by the circumstance that the mother is, at the time of the child’s conception and birth, married to, and cohabitating with, another man, both of whom wish to raise the child as the offspring of their union. It is a question of legislative policy and not constitutional law whether California will allow the presumed parenthood of a couple desiring to retain a child conceived within and born into their marriage to be rebutted.
  We do not accept Justice Brennan’s criticism that this result “squashes” the liberty that consists of “the freedom not to conform.” Post, at 141. It seems to us that reflects the erroneous view that there is only one side to this controversy — that one disposition can expand a “liberty” of sorts without contracting an equivalent “liberty” on the other side. Such a happy choice is rarely available. Here, to provide protection to an adulterous natural father is to deny protection to a marital father, and vice versa. If Michael has a “freedom not to conform” (whatever that means), Gerald must equivalently have a “freedom to conform.” One of them will pay a price for asserting that “freedom” — Michael by being unable to act as father of the child he has adulter-ously begotten, or Gerald by being unable to preserve the integrity of the traditional family unit he and Victoria have established. Our disposition does not choose between these two “freedoms,” but leaves that to the people of California. Justice Brennan’s approach chooses one of them as the constitutional imperative, on no apparent basis except that the unconventional is to be preferred.
  > t — (
  We have never had occasion to decide whether a child has a liberty interest, symmetrical with that of her parent, in maintaining her filial relationship. We need not do so here because, even assuming that such a right exists, Victoria’s claim must fail. Victoria’s due process challenge is, if anything, weaker than Michael’s. Her basic claim is not that California has erred in preventing her from establishing that Michael, not Gerald, should stand as her legal father. Rather, she claims a due process right to maintain filial relationships with both Michael and Gerald. This assertion merits little discussion, for, whatever the merits of the guardian ad litem’s belief that such an arrangement can be of great psychological benefit to a child, the claim that a State must recognize multiple fatherhood has no support in the history or traditions of this country. Moreover, even if we were to construe Victoria’s argument as forwarding the lesser proposition that, whatever her status vis-a-vis Gerald, she has a liberty interest in maintaining a filial relationship with her natural father, Michael, we find that, at best, her claim is the obverse of Michael’s and fails for the same reasons.
  Victoria claims in addition that her equal protection rights have been violated because, unlike her mother and presumed father, she had no opportunity to rebut the presumption of her legitimacy. We find this argument wholly without merit. We reject, at the outset, Victoria’s suggestion that her equal protection challenge must be assessed under a standard of strict scrutiny because, in denying her the right to maintain a filial relationship with Michael, the State is discriminating against her on the basis of her illegitimacy. See Gomez v. Perez, 409 U. S. 535, 538 (1973). Illegitimacy is a legal construct, not a natural trait. Under California law, Victoria is not illegitimate, and she is treated in the same manner as all other legitimate children: she is entitled to maintain a filial relationship with her legal parents.
  We apply, therefore, the ordinary “rational relationship” test to Victoria’s equal protection challenge. The primary rationale underlying §621’s limitation on those who may rebut the presumption of legitimacy is a concern that allowing person's other than the husband or wife to do so may undermine the integrity of the marital union. When the husband or wife contests the legitimacy of their child, the stability of the marriage has already been shaken. In contrast, allowing a claim of illegitimacy to be pressed by the child — or, more accurately, by a court-appointed guardian ad litem — may well disrupt an otherwise peaceful union. Since it pursues a legitimate end by rational means, California’s de-cisión to treat Victoria differently from her parents is not a denial of equal protection.
  The judgment of the California Court of Appeal is
  Affirmed.
  In those circumstances in which California allows a natural father to rebut the presumption of legitimacy of a child born to a married woman, e. g., where the husband is impotent or sterile, or where the husband and wife have not been cohabiting, it is more likely that the husband already knows the child is not his, and thus less likely that the paternity hearing will disrupt an otherwise harmonious and apparently exclusive marital relationship.
  We do not understand what Justice Brennan has in mind by an interest “that society traditionally has thought important . . . without protecting it.” Post, at 140. The protection need not take the form of an explicit constitutional provision or statutory guarantee, but it must at least exclude (all that is necessary to decide the present case) a societal tradition of enacting laws denying the interest. Nor do we understand why our practice of limiting the Due Process Clause to traditionally protected interests turns the Clause “into a redundancy,” post, at 141. Its purpose is to prevent future generations from lightly casting aside important traditional values — not to enable this Court to invent new ones.
  Justice Brennan asserts that only a “pinched conception of ‘the family’ ” would exclude Michael, Carole, and Victoria from protection. Post, at 145. We disagree. The family unit accorded traditional respect in our society, which we have referred to as the “unitary family,” is typified, of course, by the marital family, but also includes the household of unmarried parents and their children. Perhaps the concept can be expanded even beyond this, but it will bear no resemblance to traditionally respected relationships — and will thus cease to have any constitutional significance — if it is stretched so far as to include the relationship established between a married woman, her lover, and their child, during a 3-month sojourn in St. Thomas, or during a subsequent 8-month period when, if he happened to be in Los Angeles, he stayed with her and the child.
  Justice Brennan insists that in determining whether a liberty interest exists we must look at Michael’s relationship with Victoria in isolation, without reference to the circumstance that Victoria’s mother was married to someone else when the child was conceived, and that that woman and her husband wish to raise the child as their own. See post, at 145-146. We cannot imagine what compels this strange procedure of looking at the act which is assertedly the subject of a liberty interest in isolation from its effect upon other people — rather like inquiring whether there is a liberty interest in firing a gun where the case at hand happens to involve its discharge into another person's body. The logic of Justice Brennan’s position leads to the conclusion that if Michael had begotten Victoria by rape, that fact would in no way affect his possession of a liberty interest in his relationship with her.
  According to Justice Brennan, Michael does not claim — and in order to prevail here need not claim — a substantive right to maintain a parental relationship with Victoria, but merely the right to “a hearing on the issue” of his paternity. Post, at 156, n. 12. “Michael’s challenge . . . does not depend,” we are told, “on his ability ultimately to obtain visitation rights.” Post, at 147. To be sure it does not depend upon his ability ultimately to obtain those rights, but it surely depends upon his asserting a claim to those rights, which is precisely what Justice BRENNAN denies. We cannot grasp the concept of a “right to a hearing” on the part of a person who claims no substantive entitlement that the hearing will assertedly vindicate.
  Justice Bkkxnan criticizes our methodology in using historical traditions specifically relating to the rights of an adulterous natural father, rather than Inquiring more generally “whether parenthood is an interest that historically lias received our attention and protection.” Pont, at 139. 'Hiere seems to us no basis for the contention that this methodology is “nove[l|," post, at 140. For example, in Bowers v. Hardwick, 478 U. S. 186 (1986), we noted that at the time the Fourteenth Amendment was ratified all but ó of the 37 States had criminal sodomy laws, that all 50 of the States had such laws prior to 19(31, and that 24 States and the District of Columbia continued to have them; and we concluded from that record, regarding that very specific aspect of sexual conduct, that “to claim that a right to engage in such conduct is ‘deeply rooted in this Nation’s history and tradition’ or ’implicit in the concept of ordered liberty’ is, at best, facetious." Id., at 191. In Roe v. Wade, 410 U. S. 113 (1973), we spent about a fifth of our opinion negating the proposition that there was a longstanding tradition of laws proscribing abortion. Id., at 129-141.
  We do not understand why, having rejected our focus upon the societal tradition regarding the natural father’s rights vis-a-vis a child whose mother is married to another man, Justice Bkennan would choose to focus instead upon “parenthood.” Why should the relevant category not be even more general — perhaps "family relationships”; or “personal relationships"; or even “emotional attachments'in general”? Though the dissent has no basis for the level of generality it would select, we do; We refer to the most specific level at which a relevant tradition protecting, or denying protection to, the asserted right can be identified. If, for example, there were no societal tradition, either way, regarding the rights of the natural father of a child adulterouslv conceived, we would have to consult, and (if possible) reason from, the traditions regarding natural fathers in general. But there is such a more specific tradition, and it unqualifiedly denies protection to such a parent.
  One would think that Justice Brennan would appreciate the value of consulting the most specific tradition available, since he acknowledges that ‘'[e]ven if we can agree . . . that ‘family’ and ‘parenthood' are part of the good life, it is absurd to assume that we can agree on the content of those terms and destructive to pretend that we do." Pont, at 141. Because such general traditions provide such imprecise guidance, they permit judges to dictate rather than discern the society's views. The need, if arbitrary decisionmaking is to be avoided, to adopt the most specific tradition as the point of reference —or at least to announce, as .Justice Bkennan declines to do, some other criterion for selecting among the innumerable relevant traditions that could be consulted —is Well enough exemplified by the fact that in the present case Justice Brennan's opinion and Justice O'Connor's opinion, post, p. 132, which disapproves this footnote, both appeal to tradition, but on the basis of the tradition they select reach opposite results. Although assuredly having the virtue (if it be that) of leaving judges free to decide as they think best when the unanticipated occurs, a rule of law that binds neither by text nor by any particular, identifiable tradition is no rule of law at all.
  Finally, we may note that this analysis is not inconsistent with the result in cases such as Griswold v. Connecticut, 381 U. S. 479 (1965), or Eisenstadt v. Baird, 405 U. S. 433 (19721. None of those cases acknowledged a longstanding and still extant societal tradition withholding the very right pronounced to be the subject of a liberty interest and then rejected it. Justice Brennan must do so here. In this case, the existence of such a tradition, continuing to the present day, refutes any possible contention that the alleged right is “so rooted in the traditions and conscience of our people as to be ranked as fundamental," Snyder v. Massachusetts, 291 U. S. 97, 105 (1934), or “implicit in the concept of ordered liberty,” Palko v. Connecticut, 302 U. S. 319, 325 (1937).
  Justice Brennan chides us for thus limiting our holding to situations in which, as here, the husband and wife wish to raise her child jointly. The dissent believes that without this limitation we would be unable to “rely on the State’s asserted interest in protecting the ‘unitary family’ in denying that Michael and Victoria have been deprived of liberty.” Post, at 147. As we have sought to make clear, however, and as the dissent elsewhere seems to understand, see post, at 139,140-141,145,147, we rest our decision not upon our independent “balancing” of such interests, but upon the absence of any constitutionally protected right to legal parentage on the part of an adulterous natural father in Michael’s situation, as evidenced by long tradition. That tradition reflects a “balancing” that has already been made by society itself. We limit our pronouncement to the relevant facts of this case because it is at least possible that our traditions lead to a different conclusion with regard to adulterous fathering of a child whom the marital parents do not wish to raise as their own. It seems unfair for those who disagree with our holding to include among their criticisms that we have not extended the holding more broadly.