In the case of Geduldig v. Aiello (1973), the US Supreme Court ruled that California's disability insurance program, which excluded pregnancy-related disabilities from coverage, did not violate the Equal Protection Clause of the Fourteenth Amendment. The court held that this exclusion was not a sex-based discrimination since it didn't discriminate against women as a whole but only against pregnant women. Furthermore, they argued that while only women can become pregnant, not all women are pregnant or will become so; hence it wasn’t discriminatory towards all females in general. This decision led to significant public criticism and eventually contributed to Congress passing the Pregnancy Discrimination Act in 1978.

In the dissenting opinion for Geduldig v. Aiello, Justice Brennan argued that the majority's decision was a clear violation of the Equal Protection Clause of the Fourteenth Amendment. He asserted that pregnancy discrimination is inherently sex-based and therefore should be subject to strict scrutiny under equal protection law. According to him, excluding pregnancy from disability benefits essentially amounted to state-sanctioned gender discrimination because only women can become pregnant. Furthermore, he criticized the majority's argument about insurance risk as irrelevant since it failed to address whether or not there was an unconstitutional classification based on sex in this case. In his view, California’s disability insurance system unjustly discriminated against female employees by denying them equal protection under its laws due to their biological capacity for pregnancy.