Not all legislatures consist only of one chamber; particularly in larger countries, many are bicameral. Around the world, about two-thirds of all countries have unicameral legislatures, while the remaining one-third have some kind of second chamber.
Most second chambers (often called upper houses or senates) exist for one or both of two reasons. The first is to provide a different type of representation or represent different interests, most often the regions or provinces of a country. The second is to act as a ‘house of review’, to provide a brake or delay against impetuous decisions in a lower chamber. The powers of upper houses are often less than those of lower chambers, especially when they are chambers of review.
The structures of these vary widely, but in general the most common use of second chambers is in federal systems to represent the constituent units of the federation. For example, the states in the USA, Brazil, and Australia, the Länder in Germany, and the provinces in South Africa are all separately represented in an upper house. Typically, this involves a weighting in favour of the smaller states or provinces, as there tends to be an assumption of equality of representation between them. In addition, many second chambers feature staggered elections: half the chamber is elected every three years in Australia and Japan; one-third of the chamber is elected every second year in the USA and India, and so on.
Some countries whose upper houses are ‘houses of review’ place special restrictions on them. In Thailand, for example, the Senate is now elected, but senators are prohibited from belonging to a political party or campaigning for election. A less common type of alternative representation is the deliberate use of the second chamber to represent particular ethnic, linguistic, religious, or cultural groups.
A second chamber may also deliberately contain representatives of civil society. In Malawi, for instance, before the Senate was abolished in 2001, the constitution provided for 32 of the 80 senators to be chosen by elected senators from a list of candidates nominated by social ‘interest groups’. These groups are identified as women’s organizations, the disabled, health and education groups, the business and farming sectors, the trade unions, eminent members of society, and religious leaders. The much-maligned British House of Lords is occasionally defended on the grounds that it contains individuals with specific policy expertise who can check government legislation drawn up by generalist politicians. Similarly, second chambers in countries like Fiji and Botswana are used to represent traditional chiefs, although these are appointed in the first case and elected in the second.
Because of these variations, many second chambers are partly elected, indirectly elected or unelected. Of those that are elected, most jurisdictions have chosen to reflect the different roles of the two houses by using different electoral systems for the upper house and the lower house. In Australia, for example, the lower house is elected by a majoritarian system (AV) while the upper house, which represents the various states, is elected using a proportional system (STV). This has meant that minority interests which would normally not be able to win election to the lower house still have a chance of gaining election, in the context of state representation, in the upper house. In Indonesia, the lower house is elected by List PR, while the upper house uses SNTV to elect four representatives from each province. In Colombia, while both houses are elected by PR, the Senate is elected from one nationwide district, thus making it more likely that small parties and minority interests will be represented in that chamber.
