421 U.S. 7 (1975)
Thelma B. Stanton and James Lawrence Stanton, Jr., married in Elko, Nevada, in February 1951.1 They were divorced in Utah on November 29, 1960.2 The couple had a daughter, Sherri Lyn, born in February 1953, and a son, Rick Arlund, born in January 1955.3 During the divorce proceedings in the District Court of Salt Lake County, the parties entered into a stipulation as to property, child support, and alimony.4 The court awarded custody of the children to their mother and incorporated the stipulation into its decree, ordering the father to pay three hundred dollars per month, consisting of one hundred dollars for each child as support and one hundred dollars as alimony.5
The appellant remarried, after which the court modified the decree to relieve the appellee from further alimony payments.6 The appellee also later remarried.7 When Sherri attained eighteen on February 12, 1971, the appellee discontinued payments for her support.8 Rick attained eighteen on January 29, 1973.9 In May 1973 the appellant moved the divorce court for entry of judgment for support for the children after each respectively attained the age of eighteen.10 The court concluded that Sherri had become eighteen and thereby attained her majority under Utah Code Annotated section 15-2-1, so the appellee was not obligated for her maintenance and support after that date.11
The appellant appealed to the Supreme Court of Utah, contending that the statute's different ages of majority for males and females denied due process and equal protection.12 The Utah court affirmed the denial of support for Sherri after age eighteen.13 The United States Supreme Court noted probable jurisdiction.14
The appellee suggested that the support issue was moot and that the appellant lacked standing, but the proceedings continued to address those contentions along with the merits of the statutory challenge.15
Whether the support issue is moot because both the appellant and her daughter are now over twenty-one?16
The obligation issue, then, plainly presents a continuing live case or controversy. It is neither moot nor nonjusticiable.17
No. Although both the appellant and Sherri are now over twenty-one, the issue concerns support for the daughter during her years between eighteen and twenty-one.18 If the appellee is obligated under the divorce decree for that period, there is an amount past due and owing.19 The obligation issue thus presents a continuing live case or controversy that is neither moot nor nonjusticiable.20
The support issue is not moot.21
Whether the appellant lacks standing to challenge the Utah statute because she is not in the age group affected by it?22
To have standing a party must possess a personal stake in the outcome of the controversy sufficient to assure concrete adverseness that sharpens the presentation of issues.23
No. The appellant has a personal stake because under Utah law she herself had a legal obligation to support her daughter until age twenty-one.24 Her interest in any obligation of the appellee for support between ages eighteen and twenty-one is distinct and significant whether viewed as personal or fiduciary.25 Nothing in the stipulation waives that interest.26
The appellant has standing to challenge the statute.27
Whether the Utah statute specifying a greater age of majority for males than for females denies equal protection of the laws in the context of a parent's obligation for child support payments?28
A classification based on sex must be reasonable, not arbitrary, and must rest upon some ground of difference having a fair and substantial relation to the object of the legislation, so that all persons similarly circumstanced shall be treated alike.29
Yes. The distinction drawn by the statute when related to the divorce decree results in liability for support for the daughter only to age eighteen but for the son to age twenty-one.30 This imposes criteria wholly unrelated to the objective of the statute.31 A child, male or female, is still a child.32 No longer is the female destined solely for the home and the rearing of the family, and only the male for the marketplace and the world of ideas.33
The classification does not survive equal protection attack under any test.34
The Utah statute denies equal protection of the laws in the context of child support.35