Writing for a plurality of the Court, Justice William Brennan (joined by by Justices Douglas, White, and Marshall) first established that sex is an immutable characteristic that “frequently bears no relation to ability to perform or contribute to society,” so “statutory distinctions between the sexes often have the effect of invidiously relegating the entire class of females to inferior legal status without regard to the actual capabilities of its individual members.” Therefore, he concluded that sex-based classifications are inherently suspect and must be subject to strict judicial scrutiny like classifications based on race, alienage, or national origin.

The government conceded that its rule served no purpose other than “administrative convenience, but Brennan pointed out that it offered no concrete evidence to support its assertion. He noted that the Court’s decision in Stanley v. Illinois (1972) “make[s] clear that, although efficacious administration of governmental programs is not without some importance, ‘the Constitution recognizes higher values than speed and efficiency.’” He added that “when we enter the realm of ‘strict judicial scrutiny,’ there can be no doubt that ‘administrative convenience’ is not a shibboleth, the mere recitation of which dictates constitutionality.”

In his concurring opinion, Justice Lewis Powell (joined by Chief Justice Burger and Justice Blackmun) stated that he agreed that the military’s policy violated the Due Process Clause of the Fifth Amendment, he couldn’t agree with the conclusion that sex-based classifications should be held to the same level of scrutiny as those made on the basis of race or national origin. He wrote, “[i]t is unnecessary for the Court in this case to characterize sex as a suspect classification, with all of the far-reaching implications of such a holding.”