Why did some parties but not others allow 'conscience voting' on the SkyCity deal, despite the Speaker ruling that it was to be a conscience vote?
Do standing orders allow Party Leaders to whip their MPs on a conscience vote?
Yes – the Speaker cannot direct parties or MPs on their votes, only on the manner of voting. When the Speaker rules that a conscience vote will be held, members must be present physically and have their vote individually recorded in the lobbies.
This is how all votes once worked in our House (and at Westminster). Two nominees from each side of the House are appointed 'tellers' to count the votes (noes and ayes). Today the tellers mark off the names of MPs on a list. The nominees agree the number.
For convenience, parties in the New Zealand parliament now usually cast proxy votes via their whips or a nominated member of the party. But that does not prevent any MP crossing the floor on any vote.
The 'whip' (or musterer for the Greens) wields party discipline. If you choose not to accept a collective decision you weaken your party's ability to influence matters in future. You will be unable to assure support on the compromises that democracy demands.
Parties tend to withdraw the whip to allow a conscience vote according to whether it helps or hinders the party.
A conscience vote is permitted for the protection of a party brand where there will be strong conflicting views among supporters of the party. The party wants to avoid the issue being a permanent turn-off to disappointed supporters. They will remember the vote for the 'wrong' side, whereas those who approved of the vote have shorter memories, and their added loyalty may be trivial compared to the long term disgruntlement of disppointed supporters.
So on controversial issues that raise no strong issue of party principle, a conscience vote will ensure its brand is not attached to the wrong side. It leaves MPs in the party on both sides so there is always someone to whom the opposing supporters can remain loyal.
From the MP perspective the annoucement of a conscience vote ensures that 'floor crossing' is not seen as disloyalty even when there is a clear preferred party position.
Parties use it to make a virtue of necessity, and often try to claim spurious moral superiority over the party that requires the normal party discipline that protects us from unpredictable and chaotic vote trading issue by issue. That system bedevils many of the younger parliamentary democracies.