Unicameral Legislature

A unicameral system is one in which seats in the legislative branch are recruited for, and allotted to, a single assembly. Unicameral legislatures exist in democracies such as Denmark, Finland, Greece, Israel, Luxembourg, New Zealand, Portugal, and Costa Rica, as well as frequently at the level of subnational government. Unicameralism is correlated to the size of polities by population. In states with populations lower than 100,000, 78% of legislatures are unicameral. Yet in states of over 10 million people, unicameralism becomes increasingly rare. As a concept, unicameralism is situated within the debate over the appropriate exercise of legislative power. Proponents of unicameralism deny the necessity of constraining legislative power by dividing the legislative branch into two houses with separate roles. Some ways in which this argument has been made is with reference to the two-party system or the supermajority rule. The battle lines of this debate lie between the need for assurances against imprudent or harmful legislative activity and the need to reduce decision-making costs and promote democratic practices.

It could be argued that unicameral legislatures are appropriate for two-party systems in which voters elect a government based on the superior of two alternatives. Under such a system, government can only be accountable for the deeds it has performed on its own behalf. As such, any intervention by an opposition upper house in the legislative process could implicate the opposition in the government's overall performance, and in turn, blur the line of accountability. In other words, for a government to do good it needs to be able to do evil. However, it is not clear to what extent this amounts to an argument against the two-party system itself or for an upper house of limited powers. Defenders of bicameralism dispute the notion that government accountability is a one-stage game that only takes place during an election.

One way to make the unicameral system conform to a standard of checks and balances on legislative power is to implement a supermajority rule under which support of two thirds of the assembly is required to pass legislation. This constraint would make it difficult for a “tyranny of the majority” to emerge in which a group of legislators is led by a mendacious or illiberal agenda setter. Moreover, it would ostensibly promote consensus among diverse political groups. Whether this would raise decision-making costs is less than obvious because legislating with dispatch is a benefit that may produce impetuosity in equal measure, which, arguably, is a decision-making cost also. Critics of this proposal would contend that constraints on legislative power can be achieved with lower decision-making costs in a bicameral system with a simple majority rule in each house. Supporters of unicameralism remain skeptical, however, because upper houses are often perceived as undemocratically favoring geographical minorities because the district magnitude for upper house electorates in many federal systems remains constant regardless of the population size [Page 678]of constituencies. One could remedy this by manipulating the rules of upper house recruitment. The problem, however, is achieving this in a manner that still allows upper houses to remain distinct in their role from lower houses. Without this differentiation, second chambers become redundant because their existence is premised on the virtue of allowing legislation to receive scrutiny from a variety of perspectives.

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