The primary election for selecting candidates is a uniquely American innovation. First adopted in Wisconsin in 1905, it has since spread to every other state. Generally it is the required method for selecting major political parties ' nominees, whose names are automatically placed on the general election ballot, and for narrowing the field in nonpartisan elections.
The Supreme Court has not heard a modern constitutional challenge to state authority to compel political parties to select their candidates at primaries or to define party membership for these purposes. In Cousins v. Wigoda (1975), however, the Supreme Court held that Illinois could not require the Democratic National Convention to seat delegates selected in the state's primary; and in Democratic Party v. LaFollette (1981) the Court held that Wisconsin's delegates could not be bound by state law to follow candidate preferences expressed by voters in the state's presidential primary. In both cases, the Justices declared that the "party and its adherents enjoy a constitutionally protected right of political association." And in Democratic Party the Court said that "the freedom to associate … necessarily presupposes the freedom to identify the people who constitute the association, and to limit association to those people only." The Justices recognized state interests in the conduct of primary elections, however, and their decisions specifically addressed attempts to regulate the conduct of national party conventions and delegates. States might be able to limit the privilege of automatic access to the ballot to those parties conforming with state primary laws.
The Supreme Court has upheld state primary laws that protect the interests of political parties. In 1976 it affirmed a lower court judgment upholding a state's closed primary against a challenge that it abridged the right to vote and violated the right of privacy in political affiliation and belief. Similarly, the Court upheld, in Rosario v. Rockefeller (1973), an extended waiting period for voters wishing to change party registration, thus protecting party primaries from invasion by opposition party adherents and from casual participation by independent voters. But in Kusper v. Pontikes (1973), the Court acknowledged a competing interest in voter participation by rejecting a waiting period so long that the voter wishing to change party affiliation was excluded entirely from at least one primary election.
The Supreme Court has concluded that Congress has authority to regulate primary elections to nominate candidates for federal office, including prohibition of fraud, bribery, and other practices that deprive voters of rights, in united states v. classic (1941) and Burroughs v. United States (1934), and regulation of political finance practices, in buckley v. valeo (1976). Additional authority to regulate primaries is encompassed within the enforcement clauses of the fourteenth and fifteenth amendments.
The principal clauses of these amendments also have independent application to primary elections, apart from any regulatory legislation Congress may enact. Once a state has established the primary for nominating candidates, the one person, one vote principle of the apportionment cases applies. racial discrimination in primaries has been held unconstitutional, whether these barriers are established by the state, as in nixon v. herndon (1927), or by political parties pursuant to state authorization to define party membership, as in nixon v. condon (1932) and smith v. allwright (1944). Racial discrimination has also been held unconstitutional in a primary operated exclusively by a political party following the state's repeal of its primary election system. The most farreaching application of the Fifteenth Amendment, in terry v. adams (1953), prohibited racial discrimination in a "pre-primary" straw vote conducted by an all-white political club, when such "pre-primaries" had regularly proved determinative of elections.
In Cousins v. Wigoda the Supreme Court held that state primary laws do not supersede the authority of national party conventions over the selection and seating of delegates, but it did not choose to make a broad decision between competing claims of freedom of association of political parties and governmental authority to regulate nomination activities. On one side of this continuing constitutional controversy lie assertions of first amendment rights of parties to define their own membership, to control the composition and operation of party bodies, and to nominate candidates. On the other side lie assertions of state and congressional authority to regulate elections, of congressional power specifically granted in the enforcement clauses of the Fourteenth and Fifteenth Amendments, and of the independent operation of the principal clauses of those amendments. Notwithstanding the Supreme Court's reluctance to decide this question broadly, the Court's decisions have increasingly recognized the freedom of association of political parties.