There are some big problems in squaring bicameralism with Westminsterian parliaments. First and foremost, from whom must the executive seek confidence? If an important bill fails in a Parliamentary system, there must typically be a confidence vote. Would a Kiwi senate striking down a piece of legislation trigger a no-confidence vote? If so, then all of MMP's problems with coalition formation return. If not, and the Senate can strike down money bills, what happens in case of deadlock? I've no particular problem with deadlocks, but they don't sit well with the notion of Parliamentary supremacy.
Malpass and Hartwich suggest adopting the Australian system where the Prime Minister can dissolve both houses and hold a full re-election should a government bill be twice rejected by the Senate. This solves one problem, but eliminates a potential benefit of bicameralism: namely, having an upper house elected on a much longer term than the lower house to insulate policy from the transient whims of the electorate.
Brook-Cowen, Cowen and Tabarrok's 1992 primer on constitutional change in New Zealand suggests that, relative to the unicameral first past the post system then operant, bicameralism offered little.
In New Zealand, the introduction of a strong second chamber would fundamentally alter the nature of accountability in government, and in a manner which would in our view be unsustainable. Westminster systems of government revolve around the accountability of the executive to parliament. With two equally powerful but differently composed chambers, the executive will face continuing conflicts in defining the interests to which it is accountable. As a result of these conflicts, we might expect a general weakening of accountability to the electorate. In particular, we would expect:The status quo has of course changed since then. MMP means that Parliamentary parties must form coalitions to govern; forming coalitions across houses ought not be particularly more difficult than forming them within houses. So the costs of adding a second chamber are now much lower than they were from the 1992 status quo. But it's not clear to me that the main problems of the current system - too short an electoral time horizon, difficulty in ascribing responsibility in coalitions, generally excessive power for minor players - would much be solved by adding a second chamber.
Accountability conflicts of the kind described here are not necessary features of bicameral systems. Rather, they are a product of the particular combination of strong bicameralism and a Westminster parliamentary system. Strong bicameralism and accountable government could, by contrast, be combined if New Zealand were to adopt a more consensual system of government (for example, with the first chamber being elected on a proportional representation rule), or a presidential system of government (with executive power distanced from the legislature).
- a reduced incentive on the part of politicians to mirror the preferences of the median voter;
- an increased incentive to serve the interest of strong special interest groups;
- an increased incentive to maximise revenue and redistribute resources from citizens to the government;
- an increased incentive to favour particular regions and districts at the expense of other regions and districts; [fn: This outcome will hold where the second chamber is elected under a federal system or by means of regionally-based proportional representation.]
- an increased incentive for politicians to indulge their own policy preferences or ideology;
- a reduced incentive to respond favourably to international constraints.
The best argument I've seen for a second chamber is that it slows the implementation of reform such that it's more likely to be embedded: Australia having taken the slower route to economic reform but having brought more voters along. But would a bicameral system as here proposed really slow things down that much?
Every three years we'd vote for a lower house by FPP and for an upper house by regionally-based PR. It's the rare case in which the party with the smaller fraction of the vote gets a Parliamentary majority under FPP. It happens, but not all that often. So the dominant lower house party would also be the dominant upper house party. In the lower house, it would likely have a majority; in the upper house, it would have to form coalitions with minor parties. I'm not sure I see much difference between a large centrist party having to form coalitions in a unicameral parliament and that same large centrist party having to form coalitions in one house of a bicameral system. Moreover, as the party lists developed for Senate elections would be controlled by the party apparatus, the odds of there being substantial within-party differences across the two houses are slight.
I'd modify Malpass's proposal as follows:
- House elections (FPP) every four years; Senate terms of eight years with staggered terms - half elected each time there's an election in the House
- Senate elected by a national PR vote rather than regional PR to reduce geographical coalitions across houses: enough incentives for geographical redistribution in the lower house; demographically-based coalitions in the upper house should check the worst geographic pork-barreling (though massively attenuated as upper house parties are clients of lower house via party list structure)
- The Australian double-dissolution trigger seems a good one. The Executive is beholden to the House for confidence, but a bill twice rejected by the Senate lets the Prime Minister dissolve both houses for election; in that case, some Senatorial seats would be up for three-year and others up for six-year terms.