[Update: I am adding this to the Germany block, due to a discussion that has arisen in the comments.]
Under New Zealand’s variant of Mixed-Member Proportional (MMP), there are two alternative thresholds for receiving party-list seats. Either a party must obtain over 5% of the party-list vote, or else it must win a single district (electorate) and sufficient party-list votes to elect two or more MPs in total (even if its list vote is under 5%).
The latter path towards winning proportional representation seats is referred to in New Zealand as “coat-tailing”. I suppose New Zealanders can call it whatever they want, as long as it is clear to them, given that it’s their electoral system and a problem pretty much unique to them. But I don’t like the term. I understand coat tails as support on one vote (e.g. for congress) that is enhanced by having a popular candidate for another (e.g. president). But that is not what we see in New Zealand. We are talking about an alternative threshold for representation in a single institution, not voting across institutions. Moreover, a case of high coattails normally would mean reduced ticket-splitting. By contrast, in New Zealand, what seems to trouble many commentators (including the Electoral Commission in its MMP Review) is precisely incentives to ticket-split, not by abandoning a small party on the electorate vote (which might be the “normal” type of split-ticket voting under MMP), but in favor of a small party in the electorate vote. For example: National-favoring voters in Epsom voting for the local Act candidate, who had a chance at winning the electorate (and did indeed win it), but giving their list vote to National. The objection is that these voters seem to have more weight by virtue of living in a district that is so safe for one party that a small partner party can win it. But that’s not coattails, as usually understood.
In any case, this was not meant to be just a screed over terminology (though who doesn’t love such screeds?). I wanted to note that a new party in New Zealand, the Internet Party, can win seats only through this provision, whatever we might call it. The IP (good acronym for them!) has formed an alliance with the Mana Party, whose leader, Hone Harawira, has a safe Maori electorate (Te Tai Tokerau).* If Internet Mana were to win enough list votes for two seats, but elect only the one Mana candidate, then the IP would get a candidate via the list (its leader holds the number one slot on the joint list), even without coming near 5% of the list vote. In fact, about 1.3% of the vote would be sufficient.**
Yet the IP actually is against the so-called coat-tailing!
There seems to be a flaw in the process, and it is not necessarily the provision for the alternative threshold. It is in how alliances are allowed to take advantage:
In the Internet Party’s case it could potentially create a public backlash as its alliance with Mana expires just six weeks after the election.
Yes, that would seem backlash-worthy.
As for what to call this type of entry into parliament, I offer a suggestion in the title of this post.
* In this electorate, Labour has done something clever: nominate its local candidate, Kelvin Davis, to a rather low list position. “His ranking of 18 would blunt a Mana tactic of asking people to vote for Mr Harawira because Mr Davis had a safe list spot and would be an MP anyway.”
** A potential fly in the ointment is that Mana might elect two electorate MPs, in which case IP is out of luck, unless the list vote goes considerably higher. In fact, if you are a Maori voter in the one non-safe but within-reach electorate for Mana, and you do not happen to like the alliance with IP, your strategy is clear: vote for the Mana candidate, and you get to help block the IP.