Degressive proportionality is a type of formula for electing the members of a legislature or other decision-making body. If a body is elected by a number of regions, states or other subdivisions, degressive proportionality means that while the subdivisions do not each elect an equal number of members, smaller subdivision are 'overrepresented' in terms of their population.

If the equal representation of subdivisions is used, then each subdivision elects the same number of members. On the other hand if apportionment on the basis of population is used, then each subdivision elects a number of members strictly proportionate to its population. Degressive proportionality means any intermediate method that is a compromise between these two approaches. As a term it does not describe any one particular formula.

European parliament

Under the Treaty of Lisbon

Treaty of Lisbon

The Treaty of Lisbon of 1668 was a peace treaty between Portugal and Spain, concluded at Lisbon on 13 February 1668, through the mediation of England, in which Spain recognized the sovereignty of Portugal's new ruling dynasty, the House of Braganza....

, the European Parliament

European Parliament

The European Parliament is the directly elected parliamentary institution of the European Union . Together with the Council of the European Union and the Commission, it exercises the legislative function of the EU and it has been described as one of the most powerful legislatures in the world...

 uses a system of degressive proportionality to allocate its 750 seats among the member states of the European Union

European Union

The European Union is an economic and political union of 27 independent member states which are located primarily in Europe. The EU traces its origins from the European Coal and Steel Community and the European Economic Community , formed by six countries in 1958...

. Treaty negotiations, rather than a specific formula, determine the apportionment between member states.

Minimum seats

Any system that reserves a minimum number seats for a sub-body is to some extent degressively proportional. The most famous example is perhaps the election of the US presidential Electoral College. As each state has a minimum of three members of the college, smaller states such as Wyoming and Vermont effectively have disproportionally more say in the election than larger states, the extreme being California.