When I heard they were voting on a proposition that would create an “open primary,” I thought that meant the standard model — i.e., any voter is free to vote in either primary regardless of party affiliation. I … was drastically wrong.

Despite opposition from party leaders, voters approved Proposition 14 by a 54%-46% margin. The measure would allow voters to pick candidates from any political party during a primary; only the top 2 candidates would advance to a general election, regardless of party.

Supporters of the initiative said it would result in greater voter choice, and that it would lead to more moderate picks for state legislature by bringing independent voters into the primary process. But opponents said the measure would hurt third parties and independent candidates, and that the smaller number of candidates on a general election ballot would end up costing voters a choice.

Follow the link for the legal implications. Basically, so long as the candidates don’t declare any formal party affiliation but merely state that they “prefer” one party over another, that’s probably enough to make it constitutional. Otherwise, there’s a First Amendment issue in letting people who are unaffiliated with a party pick that party’s official nominee, as will happen in a “blanket primary” (which is slightly different from this). Schwarzenegger’s a big fan of the new system, and understandably so: It’s aimed at preventing fierce partisans like the nutroots and tea partiers from dominating their respective primary elections and forcing a choice between two ideologues on the public in the general election. So for instance, under California’s new system, in last night’s Nevada race a bunch of independents who might not otherwise have voted in the GOP election could have broken hard for Sue Lowden over Angle and put her and Reid on the ballot in November as the two top finishers.

Ace calls this the death of political parties, which is potentially true in deep blue or deep red states where you might end up with no Republican or Democrat on the ballot in the general election. But even so, I’m intrigued by the possibilities it’ll create for strategic voting. To revisit the Nevada example, given that Reid’s campaign desperately wanted to face Angle rather than Lowden, would a bunch of his voters have voted for Angle last night on the assumption that Reid would get enough votes anyway to finish in the top two? And, er, what if they miscalculated? Also, I’m not quite as pessimistic as Ace is about a state’s minority party being knocked off the ballot in the general for the simple reason that minority parties will know that they have to unite behind a single candidate before the vote. E.g., in Texas, a bunch of Republican candidates could afford to duke it out but Democrats would have to pick some anointed de facto nominee before the primary and pool their votes behind that person to ensure that they finish in the top two. In fact, as Chris Cillizza notes, depending upon how many ways the Republican vote is split, you could end up with a general election between two Democrats — in Texas. And if you did, that would force the state’s Republican base to either try a write-in campaign for some GOPer on election day or to line up behind the more conservative Democrat of the two, which could actually help reduce partisanship a bit by forcing voters of one party to invest in a candidate from across the aisle.

The irony is, unless the parties decide to hold “invisible primaries” beforehand so that the rank-and-file know whom to pool their votes for on primary day, this may hand more power to each party’s machine. If the machine says, “We need to unite behind Sue Lowden,” grassroots conservatives might do so simply because they fear being knocked off the ballot in the general if the GOP vote gets split between Lowden and a bunch of others. And, for a further irony, that might lead parties to make many more Sestak/Romanoff-type job offers in order to clear the field for their candidates of choice. In other words, for a supposed good government measure, there are all sorts of potentially untoward consequences. Let’s vote on it!