OPINION

SAYLOR, Judge.

The issue in this case is whether the presumption of paternity bars Timothy Strauser ("Appellant") from seeking to establish, on the basis of blood tests favorable to his claim, that he is the father of Amanda Stahr, the youngest of three children born to April Stahr ("Mother") during her marriage to Steven Stahr ("Husband"). Mother and Husband remain married, and they oppose Appellant's claim. The Superior Court concluded that in such circumstances the presumption does indeed bar Appellant from asserting such claim. We affirm.

On May 20, 1996, Appellant filed a custody complaint against Mother. In the complaint, Appellant asserted that he is Amanda's father; that Mother had acknowledged his paternity, ensured that he enjoyed frequent visits with Amanda, and sometimes entrusted Amanda to his care; and that he, Mother, and Amanda had submitted to blood tests, the results of which disclosed a 99.99% probability that he was Amanda's father. Appellant also alleged that since receiving the blood test results, Mother had interfered with his relationship with Amanda. In view of the bond that existed between him and Amanda, Appellant asserted, it would be in the child's best interests if he were granted partial custody of her.

Mother filed preliminary objections in which she sought the dismissal of Appellant's complaint on the basis of the presumption that Amanda was a child of the Stahrs' marriage (also known as the presumption of legitimacy, or of Husband's paternity). Husband filed a petition to intervene, which was granted. He then filed preliminary objections seeking, as had Mother, to have Appellant's complaint dismissed based on the presumption of paternity. He also asserted that Appellant was equitably estopped from asserting paternity, as he had not financially or emotionally supported the child.

On November 25, 1996, following a hearing on preliminary objections, the trial court entered an order stating "that the blood test results are hereby admitted and this matter shall be scheduled for a hearing on the issue of what is best for the subject child." In an accompanying memorandum, the trial court recited its factual findings, as follows: 1) Mother and Appellant had engaged in sex on at least one occasion around the time of Amanda's conception; 2) Mother and Husband were also having sex during that period of time and were using the withdrawal method of birth control; 3) Mother and Husband were married at the time of Amanda's conception and birth, remained married, and had never separated; 4) Mother had held Amanda out to others in the community as Appellant's child and had promoted a relationship between Appellant and Amanda; and 5) Husband had exhibited an attitude of indifference toward Mother and the children, which attitude promoted Mother's relationship with Appellant.

In its opinion and order of November 25, 1996, the trial court acknowledged that if it were to rely on the case law submitted by Mother and Husband, the case would be dismissed, as Appellant had failed to overcome the presumption of paternity by showing non-access or impotency on the part of Husband. Nevertheless, the trial court concluded that Mother, having held Amanda out to be Appellant's child and having voluntarily submitted to blood testing for the purpose of determining paternity, was equitably estopped from contesting Amanda's paternity. The court then decided to admit the blood test results over Husband's objection and, on the basis of those results, concluded that the presumption of legitimacy had been overcome. Accordingly, the court directed that a hearing be held "on what is best for the child."

Mother and Husband filed separate appeals, which were subsequently consolidated, to the Superior Court. The Superior Court concluded that, in view of the fact that the Stahr family remained intact and Husband had assumed parental responsibility for Amanda, the presumption of paternity in Husband's favor was irrebuttable. Therefore, the court reasoned, the blood test results should not have been admitted into evidence. The court reversed the trial court's order and dismissed Appellant's complaint with prejudice. We granted allocatur to consider whether the presumption of paternity applied in the present case.

The presumption at issue — that a child born to a married woman is the child of the woman's husband — has been one of the strongest presumptions known to the law. John M. v. Paula T., 524 Pa. 306, 312-13, 571 A.2d 1380, 1383 (Pa.), cert. denied, 498 U.S. 850, 111 S.Ct. 140, 112 L.Ed.2d 107 (1990); Cairgle v. American Radiator Standard Sanitary Corp., 366 Pa. 249, 255, 77 A.2d 439, 442 (1951). Traditionally, the presumption can be rebutted only by proof either that the husband was physically incapable of fathering a child or that he did not have access to his wife during the period of conception. Freedman v. McCandless, 539 Pa. 584, 591, 654 A.2d 529, 532 (1995); Jones v. Trojak, 535 Pa. 95, 105, 634 A.2d 201, 206 (1993); John M., 524 Pa. at 313-14, 571 A.2d at 1384; Cairgle, 366 Pa. at 255, 77 A.2d at 442. Thus, it has been held that, where the presumption applies, blood test results (existing or potential) are irrelevant unless and until the presumption has been overcome. Jones, 535 Pa. at 105, 634 A.2d at 206. It has also been held that, in one particular situation, no amount of evidence can overcome the presumption: where the family (mother, child, and husband/presumptive father) remains intact at the time that the husband's paternity is challenged, the presumption is irrebuttable. Freedman, 539 Pa. at 592, 654 A.2d at 533; Coco v. Vandergrift, 416 Pa. Super. 444, 448, 611 A.2d 299, 301 (1992). This is such a case.

Nevertheless, Appellant contends that the presumption of paternity is inapplicable. Citing this Court's plurality opinion in Brinkley v. King, 549 Pa. 241, 701 A.2d 176 (1997), Appellant argues that the presumption will no longer be applied automatically, but only where such application will further the policy on which the presumption is based. That policy is, in Appellant's view, the best interests of the child. According to Appellant, application of the presumption will not promote the best interests of the child in this instance because of the "unique facts" of the case, including the asserted fact that Mother and Husband, although married, "do not enjoy the traditional marriage and family unit." Appellant also contends that Mother and Husband are estopped by their own conduct from invoking the presumption of paternity.

Brinkley concerned the paternity of Lisa Brinkley's daughter, Audrianna. Although Audrianna was conceived during Lisa's marriage to George Brinkley, Lisa, according to her own testimony, was not having sexual relations with her husband during that time, but was having sexual relations with Richard King. George Brinkley moved out of the marital residence four months before Lisa was born, and the parties eventually divorced. Lisa filed a complaint for support against King and, after King denied paternity, a motion for adjudication of paternity. King responded with the assertion that Lisa was precluded from claiming that he was Audrianna's father because she had failed to rebut the presumption of her former husband's paternity. The trial court agreed, and the Superior Court affirmed. This Court granted allocatur "in order to review the way in which the presumption of paternity functions in Pennsylvania law." Id. at 246, 701 A.2d at 178 (footnote omitted).

In the lead opinion, the plurality (Chief Justice Flaherty, joined by Justice Cappy) set forth the fundamentals of the law of presumptive paternity, as summarized above. Among these fundamentals was the principle that "the presumption is irrebuttable when a third party seeks to assert his own paternity as against the husband in an intact marriage." Id. at 248, 701 A.2d at 179. The public policy in support of the presumption, the plurality explained, was "the concern that marriages which function as family units should not be destroyed by disputes over the parentage of children conceived or born during the marriage." Id. at 249, 701 A.2d at 180. Thus, "[t]hird parties should not be allowed to attack the integrity of a functioning marital unit, and members of that unit should not be allowed to deny their identities as parents." Id. (footnote omitted).

Having summarized the controlling principles, the plurality articulated a framework by which those principles should be applied:

[T]he essential legal analysis in these cases is twofold: first, one considers whether the presumption of paternity applies to a particular case. If it does, one then considers whether the presumption has been rebutted. Second, if the presumption has been rebutted or is inapplicable, one then questions whether estoppel applies. Estoppel may bar either a plaintiff from making the claim or a defendant from denying paternity. If the presumption has been rebutted or does not apply, and if the facts of the case include estoppel evidence, such evidence must be considered. If the trier of fact finds that one or both of the parties are estopped, no blood tests will be ordered.

Id. at 250, 701 A.2d at 180.

This analysis, as the plurality recognized, begs the question of when the presumption was to be applied. The plurality's answer, taking into account the dramatic changes in the nature of male-female relationships that had occurred since the presumption was created, was that "the presumption of paternity applies in any case where the policies which underlie the presumption [namely, the preservation of marriages] . . ., would be advanced by its application, and in other cases, it does not apply." Id. at 250-51, 701 A.2d at 181 (footnote omitted). Thus, the plurality reasoned, the presumption did not apply in the case then at bar, as there was no marriage to protect. Accordingly, the Superior Court's order was vacated and the case was remanded to the trial court for a hearing on the issue of estoppel.

Justice Zappala concurred in the result but expressed the view that the traditional definition of non-access was unnecessarily restrictive. Justice Nigro, who also concurred in the result, suggested that "the better course of action in these cases is to allow the trial court to determine paternity on a case-by-case basis, unburdened by the obligatory application of a presumption or an estoppel theory." Id. at 253, 701 A.2d at 182 (Nigro, J., concurring and dissenting). In Justice Nigro's view, the trial court should be allowed to order blood testing of both the alleged and the presumed fathers. Justice Newman, joined by Justice Castille, filed a concurring and dissenting opinion. She concurred in the view that the presumption should not apply where its purpose would not thereby be served, but also opined that, when the presumption did apply, blood tests should be available to the parties as a means of rebutting the presumption. Justice Newman agreed with the plurality that the presumption did not apply in the case before the Court, but did not agree that the case presented a question of estoppel. Accordingly, she was of the view that the case should be remanded for blood testing of Lisa, Audrianna, and King "to finally resolve the issue of Audrianna's father." Id. at 269, 701 A.2d at 190 (Newman, J., concurring and dissenting).

Although the several opinions in Brinkley reflect the criticism that has been directed toward the presumption of paternity in recent years, Appellant's reliance on that decision is unavailing. In the present case, the marriage into which Amanda was born continues. Indeed, despite the marital difficulties that they have encountered, Mother and Husband have never separated. Instead, they have chosen to preserve their marriage and to raise as a family the three children born to them, including Amanda. As this Court observed in John M.,

[t]here is, in short, a family involved here. A woman and a man who have married and lived together as husband and wife, giving birth to and raising [several] children, have obvious interests in protecting their family from the unwanted intrusions of outsiders (even ones who have had serious relationships with the mother, father or children). The Commonwealth recognizes and seeks to protect this basic and foundational unit of society, the family, by the presumption that a child born to a woman while she is married is a child of the marriage.

Id. at 317-18, 571 A.2d at 1386 (citation omitted). Thus, the present case comes within the limited set of circumstances in which, according to the Brinkley plurality, the presumption of paternity continues to apply. In this case, moreover, the presumption is not rebuttable.

Appellant argues for a different result by citing the "unique facts" of the case. He asserts that Husband and Mother's marriage lacks love and intimacy and exists in name only; Husband and Mother have experienced conflict caused by adultery; Mother represented to others that Amanda was Appellant's child; Husband suspected that Amanda was not his child; and Husband exhibited an attitude of indifference toward Mother and Amanda. In sum, Appellant asserts, Mother and Husband "do not enjoy the traditional marriage and family unit."

While Appellant's assertions may be factual, they are not unique. To the contrary, they indicate that the marriage of Mother and Husband, like many, has encountered serious difficulties. It is in precisely this situation, as was suggested in John M., that the presumption of paternity serves its purpose by allowing husband and wife, despite past mistakes, to strengthen and protect their family. Appellant's argument on this point is therefore without merit.

Nor are Husband and Mother estopped, as Appellant suggests, from invoking the presumption.

Estoppel in paternity actions is merely the legal determination that because of a person's conduct (e.g., holding out the child as his own, or supporting the child) that person, regardless of his true biological status, will not be permitted to deny parentage, nor will the child's mother who has participated in this conduct be permitted to sue a third party for support, claiming that the third party is the true father.

Brinkley, 549 Pa. at 248 n. 5, 701 A.2d at 180 n. 5 (quoting Freedman, 539 Pa. at 591-92, 654 A.2d at 532-33). As the plurality noted inBrinkley, the question of estoppel does not arise unless and until "the presumption has been rebutted or is inapplicable. . . ." Id. at 250, 701 A.2d at 180. Here, the presumption applies and is non-rebuttable. Appellant's reliance on the doctrine of estoppel is therefore unavailing.

Order affirmed.

Mr. Justice Nigro files a Dissenting Opinion.

Madame Justice Newman files a Dissenting Opinion in which Mr. Justice Castille joins.