In government, unicameralism (Latin uni-, "one" and camera, "chamber") is the practice of having a single legislative or parliamentary chamber. Thus, a unicameral parliament or unicameral legislature is a legislature which consists of a single chamber or house.
Unicameral legislatures exist when there is no widely perceived need for multicameralism. Many multicameral legislatures were created to give separate voices to different sectors of society. Multiple chambers allowed, for example, for a guaranteed representation of different social classes (as in the Parliament of the United Kingdom or the French States-General). Sometimes, as in New Zealand and Denmark, unicameralism comes about through the abolition of one of two bicameral chambers, or, as in Sweden, through the merger of the two chambers into a single one, while in others a second chamber has never existed from the beginning.
The principal advantage of a unicameral system is more democratic and efficient lawmaking, as the legislative process is simpler and there is no possibility of deadlock between two chambers. Proponents of unicameralism have also argued that it reduces costs, even if the number of legislators stays the same, since there are fewer institutions to maintain and support financially. Proponents of bicameral legislatures say that this offers the opportunity to re-debate and correct errors in either chamber in parallel, and in some cases to introduce legislation in either chamber.
