The case of Frontiero v. Richardson dealt with statutes that classify based on sex and whether they violate the Due Process Clause of the Fifth Amendment. The Supreme Court ruled that such statutes are inherently discriminatory and unjustified. The case specifically concerned the rights of female members of the military to claim their spouse as a dependent for certain benefits. The Supreme Court found that the difference in treatment between male and female servicemembers was a violation of the Due Process Clause of the Fifth Amendment. The Court held that sex-based classifications should be subject to close judicial scrutiny, similar to race, alienage, and national origin. The Court found support for this approach in Reed v. Reed, where the Court considered the constitutionality of an Idaho statute that gave a mandatory preference to male applicants over female applicants for appointment as administrator of an estate. The Court found that the statute established a classification subject to scrutiny under the Equal Protection Clause and that traditional equal protection analysis requires a legislative classification to be sustained unless it is patently arbitrary and bears no rational relationship to a legitimate governmental interest.

The Court ruled that sex-based classifications violate the basic concept of legal responsibility and often relegate females to an inferior legal status without regard to their actual capabilities. The challenged statutes in this case require dissimilar treatment for men and women who are similarly situated, and therefore are constitutionally invalid. The government's argument that the different treatment of men and women under the statutes is for administrative convenience is not supported by concrete evidence. To pass strict judicial scrutiny, the government must show that it is cheaper to grant increased benefits to all male members rather than determining which ones are entitled to benefits based on their wives' dependency. The challenged statutes that accord differential treatment to male and female members of the uniformed services for the sole purpose of achieving administrative convenience violate the Constitution, and the decision is reversed.

Justice Rehnquist agrees with Judge Rives. Justice Powell agrees that the challenged statutes are unconstitutional discrimination against servicewomen, but disagrees with Justice Brennan's opinion that all sex-based classifications should be subject to close judicial scrutiny. Powell believes that the decision can be made based on the authority of Reed v. Read and that the characterization of sex as a suspect classification should be reserved for future cases. Powell also argues that the Equal Rights Amendment, if adopted, will resolve the question at hand, and the Court should not assume a decisional responsibility that is currently being debated by state legislatures.