The bill was never Labour Party policy. But there are various reasons Labour may have decided to leave the law there, despite strong criticism of it from a raft of academics and opposition by all other parties in Parliament.
At a basic level, it could simply be because it was a National Party MP's bill to repeal it.
Last week, Labour kicked out National MP Matt Doocey's bill to increase the penalty for killing police dogs on the grounds that it was unnecessary: police dog deaths were too rare to warrant special legislation.
There are even fewer cases of MPs abandoning their parties than of police dogs being killed.
Opponents of the waka jumping bill had also argued it was a solution for a problem that barely existed. The more serious objections were that it put MPs at the mercy of party leaders. If an MP proved too naughty, a leader could turf them out. All the way out.
Perhaps ironically, it was not long after it first passed that National could have benefited from its use.
That was when former MP Jami-Lee Ross was ejected from its caucus in 2018 (and simultaneously resigned). Ross stayed on as an independent MP.
Having opposed the waka jumping law change obtained by NZ First in its coalition agreement with Labour, National opted not to invoke the powers to have Ross cast out.
Labour could also simply have decided it was bad faith to repeal the law.
Labour passed the legislation as part of the coalition agreement with NZ First. Keeping it there could be considered a signal that change agreed to and made under a coalition agreement would not be easily discarded once that coalition was over.
It would also be slightly hypocritical. The legislation was not Labour policy, and Justice Minister at the time, Andrew Little, would argue he was simply doing his job in delivering a coalition promise.
But Little had done that vigorously: proclaiming a single MP acting on a whim should not be able to derail the proportionality voters delivered.
The Green Party does not have to show the same deference to a now-defunct agreement, since it was not part of it and did not know what was in it.
There was a bout of schadenfreude when the Green Party supported Smith's bill at the first reading before the election, when NZ First was still around.
Having had to vote for it in 2018, the Green Party justified its decision to support its repeal two years later by pointing out it had agreed to allow the bill to pass. But it had never agreed not to subsequently repeal it.
In sticking to the agreement, Labour's decision to keep it on the books is insurance of sorts in case of a possible return by NZ First.
It is also insurance for a more significant possibility.
As things stand in 2021, no party has an immediate vested interest in the measure.
It is very rare for MPs to leave their parties but on the balance of probabilities, Labour is most in danger of losing an MP overboard. That is purely a mathematical calculation: it has a mammoth caucus of 64 MPs, and a large chunk are new and unknown quantities.
But Labour has four spare MPs before it loses its majority.
There is no scenario in which one MP from any party abandoning the waka would make a single jot of difference to the outcome of a law passing or a decision being made. At the moment.
Where it would matter is when a Government majority is clinched by just one MP.
Labour will not be able to hold on to its current majority forever. It will certainly not be able to keep such a healthy majority.
So it has to ponder the scenario in which one MP could be the difference between commanding a majority and losing the Government benches.
