History Behind California's Primary Election System

Closed Primary System
A "closed" primary system governed California's primary elections until 1996. In a closed primary, only persons who are registered members of a political party may vote the ballot of that political party.

Open Primary System
The provisions of the "closed" primary system were amended by the adoption of Proposition 198, an initiative statute approved by the voters at the March 26, 1996 primary election. Proposition 198 changed the closed primary system to what is known as a "blanket" or "open" primary, in which all registered voters may vote for any candidate, regardless of political affiliation and without a declaration of political faith or allegiance.

On June 26, 2000, the United States Supreme Court issued a decision in California Democratic Party, et. al. v. Jones, stating that California's "open" primary system, established by Proposition 198, was unconstitutional because it violated a political party's First Amendment right of association. Therefore, the Supreme Court overturned Proposition 198.

Modified Closed Primary System
California currently has a "modified" closed primary system. SB 28 (Ch. 898, Stats. 2000), relating to primary elections, was chaptered on September 29, 2000 and took effect on January 1, 2001. SB 28 implemented a "modified" closed primary system that permits unaffiliated ("decline to state") voters to participate in a primary election if authorized by an individual party's rules and duly noticed by the Secretary of State.
(Ch. 898, Stats. 2000)