The Stanton v. Stanton case in 1974 was a landmark decision by the U.S Supreme Court that addressed gender discrimination within family law, specifically regarding child support obligations. The dispute arose when Mr. and Mrs. Stanton divorced, with Utah state law mandating that fathers were required to provide financial support for daughters until they turned 18 but only until sons reached age 21. When their daughter turned eighteen, Mr.Stanton stopped payments arguing he had fulfilled his legal obligation under Utah's laws at the time which defined adulthood differently based on sex (age of majority). However, Mrs.Stanton disagreed and took the matter to court seeking continued support for her daughter who was still attending school full-time. The Supreme Court ruled in favor of Mrs.Stanton stating that this difference constituted unlawful gender-based discrimination violating equal protection clause under Fourteenth Amendment of Constitution.The court held such arbitrary distinctions based on sex as unconstitutional because it perpetuated stereotypes about women’s roles and capabilities compared to men's without any rational basis or justification.This ruling helped establish precedent against unequal treatment between sexes within family law context.

In the dissenting opinion for Stanton v. Stanton, Justice William Rehnquist argued that there was no constitutional violation in Utah's law setting different ages of majority for men and women (21 for males and 18 for females). He contended that the Equal Protection Clause does not forbid legislative classifications based on gender unless they are entirely irrational or arbitrary. According to him, this particular classification could be justified by biological differences between sexes and societal expectations about their respective roles. Furthermore, he pointed out that many states had similar laws at the time, suggesting a broad consensus supporting such distinctions. Therefore, he believed it was inappropriate for the Court to substitute its judgment for that of state legislatures in matters like these where reasonable people might disagree.