Setting different minimum ages for females (18) and males (21) to be allowed to buy beer is unconstitutional sex-based discrimination contrary to the Equal Protection Clause of the Fourteenth Amendment. Decided December 20, 1976 (argued October 5, 1976). Opinion of the Court: William J. Brennan → go there Dissenting: Burger, Rehnquist. Applied: the Fourteenth Amendment → go there Topic: Discrimination based on sex. Craig v. Boren, 429 U.S. 190 (1976), is a landmark decision of the U.S. Supreme Court ruling that statutory or administrative sex classifications were subject to intermediate scrutiny under the Fourteenth Amendment's Equal Protection Clause. The case was argued by future Supreme Court justice Ruth Bader Ginsburg while she was working for the American Civil Liberties Union, who later wrote for the majority in United States v. Virginia. Wiki link