On Monday, the SCOTUS heard oral arguments in Washignton's top-two primary case.Top-Two Primary Litigation
Oral Arguments before SCOTUS
Washington voters approved the top-two primary after their blanket primary had been ruled unconstitutional. In a blanket primary, candidates for the nomination from all parties are placed on a single ballot which is given to all voters. Voters are free to pick among candidates of any party for each office. The candidate with the most votes for each party is nominated and is placed on the general election ballot. Thus Republican voters could participate in the nomination of Democrat candidates and vice versa.
The SCOTUS had ruled in California Democratic Party v. Jones
that blanket primaries violated the rights of association of political parties, which includes the right to disassociate themselves from non-members. The California blanket primary was somewhat different in that it was used for one election, while Washington's had been used for decades; California had party registration, while Washington didn't (and doesn't)
California used the blanket primary system for nominating candidates of all parties. In Washington, minor parties nominated by convention a single candidate whose name then appeared on the blanket primary ballot. If the minor party nominee got enough votes (IIRC, 1%) he would advance to the general election. In California, there had been a legislative district where there was a contest for the Libertarian nomination, and not for the other parties, where twice as many persons voted in the Libertarian contest as were registered with the party.
Throughout the Jones
decision, there are suggestions that a Louisiana-style system would be acceptable because the election does not determine nominees, but rather the actual state officials. A runoff is only held when a candidate fails to secure a majority of the vote.
ruling was eventually applied to Washington. In response, the Washington legislature passed legislation providing for a top-two primary, plus a backup pick-a-party primary in case the top-two primary was ruled unconstitutional. Governor Locke vetoed the parts of the legislation that provided for the top-two primary.
In a pick-a-party (or Montana-style) primary, candidates for nomination of all parties appear on a single ballot, but voters select (on the ballot) which party's primary they are voting in. This avoids not only party registration of voters, but even public knowledge of which primary they participated in.
After Locke's veto, the top-two primary was placed on the ballot via the initiative process with the Washington Grange as the main backer. In a top-two primary, candidates of all parties appear on the primary ballot just as in a blanket primary, but the top two candidates, regardless of their party advance to the general election. Thus a top-two primary does not choose party nominees, but simply two nominees.
The Grange had promoted the top-two primary as looking exactly like a blanket primary, except that it wouldn't choose "party nominees" and thus be constitutional. There are other complications in Washington such as a party being a minor or major party based on the performance of their nominees, and legislative vacancies being filled by the political party that nominated the candidate.
Washington state argued that parties would be free to endorse particular individuals and could construct their own nomination process, and that "Republican" or "Democrat" next to a candidate's name merely indicated that individual's "party preference" and did not indicate endorsement by a party. They also suggested that the state could distinguish between nominees of the parties, and persons who merely indicated a party preference, as far as the laws for determining major party status or filling vacancies; and that there could be language on the ballot explaining to the vote the difference between the "party preference" of a candidate which was indicated on the ballot, and any endorsement by political parties (which would not be indicated on the ballot).
I could see that the SCOTUS could end up allowing a system where the parties could control which candidates can indicate a preference for their party. The parties might then institute their own nomination processes, and permit only the nominee to indicate his preference for that party. The primary ballot would then have one candidate for each party, with the D and R finishing 1, 2 or 2, 1 in most cases and going on to the general election. The most interesting races might be those in which no Democrat or Republican filed, and so the voters would decide whether a Libertarian or Green candidate advanced to the general election as the 2nd place finisher.