Cross-filing

In American politics, cross-filing (similar to the concept of electoral fusion) occurs when a candidate runs in the primary election of not only his own party, but also that of one or more other parties, generally in the hope of reducing or eliminating his competition at the general election.

In 1909, California introduced the direct primary election in its elections. The state's requirement that candidates in primary elections certify that they had supported a particular party in the previous general election was struck down by the California Supreme Court in 1909, in a case involving the Socialist Party of America. While the California State Legislature attempted to institute a looser test in 1911, by 1913, there was no longer any restriction on candidates filing in multiple primaries. The cross-filing provision was added to a previously debated primary bill by members of the administration of Governor Hiram Johnson, who had previously run (on separate occasions) as a Republican and with the Progressive Party.

In 1917 and 1919, the legislature barred a candidate who lost his own party's nomination from running as a member of any other party, and allowed the state committee of the affected party to fill any vacancies on their ticket. In combination with statutes that placed the incumbent first on the ballot and designated him by his title, these ballot rules gave a heavy advantage to incumbents.

In 1946, Governor Earl Warren, eight other state officials, twelve of the state's twenty-three U.S. representatives, and approximately three-quarters of incumbent state legislators seeking re-election were elected by winning both major primaries through cross-filing. In 1948, US Representative Richard Nixon, facing no Republican primary opponent, cross-filed and defeated Stephen Zetterberg in the Democratic primary.

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