Difference Between Bicameralism and Unicameralism

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The terms bicameralism and unicameralism refer to two different types of government. As the names suggest, a bicameral legislature consists of two separate – yet often interrelated – houses or chambers, whereas a unicameral legislature only consists of one chamber or house. Scholars and practitioners have often debated on the effectiveness of the two systems; while the bicameral system offers the opportunity of a more extensive democratic debate and is supposed to enhance stability, the unicameral system is often chosen as an alternative to speed up the legislative process.

What is Bicameralism?

A bicameral legislature consists of two separate houses or chambers (i.e. Senate and House of Representatives in the United States). The members of the two chambers are often elected by different methods and the two houses can be structured in very different ways (i.e. different number of members, different voting procedures, different tasks, etc.). Within the context of bicameral legislatures, we can distinguish perfect bicameralism and imperfect bicameralism. In the first case, the majority of votes must be reached in both chambers for a law/bill to be approved. Conversely, if one of the two houses can overrule the other, the system is called imperfect bicameralism. Today, almost half of the world democratic systems are bicameral legislatures.

What is Unicameralism?

Unicameralism is a parliamentary system that consists of only one house or chamber. The reasons for choosing a one-chamber system can be vary. For instance, in authoritarian countries, bicameral systems are very rare as there is no space for opposition and popular representation is limited. At the same time, several democratic countries (i.e. Sweden, Denmark, etc.) the system moved from a bicameral legislature to a one-chamber system. Such process was completed either by merging the two existing chambers or by completely eliminating one of the two. The shift from bicameralism to unicameralism is often made when there is no evident need for two separate chambers and when stability can be achieved and maintained even with one single house.

Difference Between Bicameralism and Unicameralism

Similarities between Bicameralism and Unicameralism

Bicameralism and unicameralism are very different systems; however, we can identify few differences between the one-house system and perfect bicameralism:

  1. During the voting process, in a unicameral system the majority of the members has to vote in order to approve a bill or pass a law. In the same way, in a perfect bicameral system, the majority of votes has to be reached in both chambers in order to approve bills and laws; and
  2. In both cases, the majority has less restraints than in the imperfect bicameral system.

What is the Difference between Bicameralism and Unicameralism?

The main difference between bicameralism and unicameralism regards the number of houses or chambers (one in the unicameral legislature and two in the bicameral system). Yet, there are few other contrasting elements that can be identified:

  1. The unicameral system limits the rights and opportunities of minority groups and does not allow for equal representation within the political system. Conversely, bicameralism enhances the opportunity of equal representation and increases the chances for minority groups to obtain a seat in the Parliament; and
  2. The bicameral system promotes stability and allow for better representation of the growing complexity of the modern political scenario. Conversely, unicameralism limits the possibility of creating political alliances and coalitions.

Bicameralism vs Unicameralism

Building on the differences outlined in the previous section, we can identify few other elements that differentiate bicameralism and unicameralism.

Bicameralism VERSUS Unicameralism


While a unicameral system consists of one single chamber or house, a bicameral legislature consists of two different houses. In the first case, the legislative process is much quicker and the risk of deadlocks is very low, although the majority has less restrictions and minority groups are often not fairly represented. In the second case, the legislative process can be slower, but the entire system is supposed to be more stable and should ensure equal representation for all (or almost all) parties.

Author: Giulia Squadrin

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