In the case of Vorchheimer v. School District of Philadelphia et al., 1976, a group of female students from Philadelphia's public high schools challenged the constitutionality of single-sex schools under the Equal Protection Clause. The plaintiffs argued that they were denied equal educational opportunities because their all-girls school did not offer courses available at boys-only counterparts and had fewer resources overall. However, the Supreme Court upheld lower court decisions in favor of maintaining separate but equal facilities for male and female students within public education systems. The majority opinion held that gender-based classifications could be justified if they served important governmental objectives and were substantially related to those objectives - in this case, providing diverse educational opportunities while accommodating social differences between sexes was deemed an acceptable objective by a plurality (4-3) vote.

In the dissenting opinion for Vorchheimer v. School District of Philadelphia, Justice William Brennan disagreed with the majority's decision to uphold single-sex public schools in Philadelphia. He argued that such a policy was inherently discriminatory and violated the Equal Protection Clause of the Fourteenth Amendment. According to him, there is no substantial evidence supporting educational benefits from single-sex education that would justify gender-based discrimination. Furthermore, he pointed out that this ruling contradicts previous decisions where similar sex-segregated policies were struck down as unconstitutional (e.g., Reed v Reed). He also criticized how these policies perpetuate harmful stereotypes about women’s roles and abilities by suggesting they need different or special treatment compared to men. Lastly, he emphasized his belief in equal access to quality education regardless of one's gender.