Under Oklahoma's semiclosed primary law, a political party may invite only its own registered members and voters registered as Independents to vote in its primary. When the Libertarian Party of Oklahoma (LPO) notified the State Election Board it wanted to open its upcoming primary to all registered voters regardless of party affiliation, the Board agreed as to Independents, but not as to other parties' members. The LPO and several Oklahomans registered as Republicans and Democrats then sued for equitable relief, alleging that Oklahoma's statute unconstitutionally burdens their First Amendment right to freedom of political association. The District Court upheld the statute on the grounds that it did not severely burden respondents' associational rights and that any burden imposed was justified by Oklahoma's asserted interests in preserving parties as viable and identifiable interest groups and in ensuring that primary results accurately reflect party members' voting. Reversing, the Tenth Circuit concluded that the statute imposed a severe burden on respondents' associational rights and was not narrowly tailored to serve a compelling state interest.

Held: The judgment is reversed, and the case is remanded.

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