dissenting.
The Court views this case as requiring a determination of whether the Utah statute specifying that males must reach a higher age than females before attaining their majority denies females the equal protection of the laws guaranteed by § 1 of the Fourteenth Amendment to the United States Constitution. The Court regards the constitutionality of Utah Code Ann. § 15-2-1 (1953) as properly at issue because of the manner in which the Supreme Court of Utah approached and decided the case. But this Court is subject to constraints with respect to constitutional adjudication which may well not bind the Supreme Court of Utah. This Court is bound by the rule, “to which it has rigidly adhered, . . . never to formulate a rule of constitutional law broader than is required by the precise facts to which it is to be applied,” Liverpool, N. Y. & Phila. S. S. Co. v. Commissioners of Emigration, 113 U. S. 33, 39 (1885), and we try to avoid deciding constitutional questions which “come to us in highly abstract form,” Rescue Army v. Municipal Court, 331 U. S. 549, 575 (1947). Fidelity to these longstanding *19rules dictates that we have some regard for the factual background of this case, as fully outlined in the Court’s opinion, before deciding the constitutional question that has been tendered to us.
The Utah statute which the Court invalidates “in the context of child support,” ante, at 17, does not by its terms define the age at which the obligation of a divorced parent to support a child ceases. The parties concede that the Stantons could have provided in their property settlement agreement that appellee’s obligation to support Sherri and Rick would terminate when both turned 18, when both turned 21, or when one turned 18 and the other turned 21. Tr. of Oral Arg. 4, 14, 23. This case arises only because appellant and appellee made no provision in their property settlement agreement fixing the age at which appellee’s obligation to support his son or daughter would terminate. The Supreme Court of Utah, faced with the necessity of filling in this blank, referred to the State’s general age-of-majority statute in supplying the terms which the parties had neglected to specify themselves.
. Had the Supreme Court of Utah relied upon the statute only insofar as it cast light on the intention of the parties regarding the child support obligations contained in the divorce decree, there would be no basis for reaching the constitutionality of the statute. In supplying the missing term in an agreement executed between two private parties, a court ordinarily looks to the customs, mores, and practice of the parties in an .attempt to ascertain what was intended. If, upon consideration of these factors, including the age-of-majority statute, the Utah Supreme Court had concluded that the Stantons intended to bestow more of their limited resources upon a son than a daughter, perhaps for the reasons stated in the opinion of that court, that strikes *20me as an entirely permissible basis upon which to construe the property settlement agreement.
On the other hand, the Supreme Court of Utah may have concluded that, the parties having failed to specify this term of the agreement, the question became one of Utah statutory law rather than one of determining the intent of the parties. If that were its determination, the constitutionality of Utah Code Ann. § 15-2-1 (1953), would indeed be implicated in this case.
I do not think it possible to say with confidence which of these two approaches was taken by the Supreme Court of Utah in this case. In addition to this difficulty, there is another element of attenuation between the claim asserted on behalf of Sherri to be treated like her brother for purposes of child support, and the actual case before us. Utah has a comprehensive scheme dealing with child support in its Uniform Civil Liability for Support Act, Utah Code Ann. § 78-45-1 et seq. (Supp. 1973). Under that Act, “child” is defined as “a son or daughter under the age of twenty-one years,” §78-45-2 (4). Thus, for purposes of any direct claim by Sherri against appellee, Utah law treats her precisely as it does her brother. The claim asserted in this case is not by Sherri, but by her mother, and the source of any claim which the mother has against appellee necessarily arises out of the voluntary property settlement agreement which they executed at the time of their divorce.
These factors lead me to conclude that the issue which the Court says is presented by this case, and which it decides, cannot properly be decided on these facts if’we are to adhere to our established policy of avoiding unnecessary constitutional adjudication. I would dismiss the appeal for that reason. Rescue Army v. Municipal Court, supra; Socialist Labor Party v. Gilligan, 406 U. S. 583 (1972).