Open primaries in the United States

An open primary is a primary election that does not require voters to be affiliated with a political party in order to vote for partisan candidates. In a traditional open primary, voters may select one party's ballot and vote for that party's nomination. As in a closed primary (such that only those affiliated with a political party may vote), the highest voted candidate in each party then proceeds to the general election. In a nonpartisan blanket primary, all candidates appear on the same ballot and the two highest voted candidates proceed to the runoff election, regardless of party affiliation. The constitutionality of this system was affirmed by the Supreme Court of the United States in Washington State Grange v. Washington State Republican Party in 2008, whereas a partisan blanket primary was previously ruled to be unconstitutional in 2000.

The arguments for open primaries are that voters can make independent choices, building consensus that the electoral process is not splintered or undermined by the presence of multiple political parties.

Voter participation

The open primary could be seen as good for voter participation. First, the open primary allows nonpartisan or independent voters to participate in the nominating process. If these voters are allowed to help select the nominees then they may be more likely to vote in the general election, since one of the candidates could be someone the non-partisan voter voted for.