Degressive proportionality

Degressive proportionality is an approach to the allocation (between regions, states or other subdivisions) of seats in a legislature or other decision-making body. Degressive proportionality means that while the subdivisions do not each elect an equal number of members, smaller subdivisions are allocated more seats than would be allocated strictly in proportion to their population.

This is an alternative to, for instance,

Degressive proportionality is intermediate between those two approaches. As a term it does not describe any one particular formula.

Each German state has three to six seats in the Bundesrat of Germany depending on its population. This means the least populous state, Bremen (with 663,000 inhabitants), has three seats while the most populous one, North Rhine-Westphalia (with 18,058,000 inhabitants), has only six seats.

Under the Treaty of Lisbon, the European Parliament uses a system of degressive proportionality to allocate its 750 seats among the member states of the European Union. Treaty negotiations, rather than a specific formula, determine the apportionment between member states.

Any system that reserves a minimum number seats for a sub-body is to some extent degressively proportional. One example is the election of the US presidential Electoral College. As each state has a minimum of three members of the college, voters in smaller states have disproportionally more say in the election than the national average.

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