UC Irvine

Second chamber sizes (in terms of seats) tend to increase with increasing population like first chamber sizes. Population seems to affect first chamber size directly, while the size of the first chamber goes on to affect second chamber size. When selected on the basis of territorial sub-units, the second chamber size tends to be around the geometric mean of first chamber size and the number of sub-units. From the viewpoint of representing the total population and the constituent sub-units, the European Parliament is more akin to a first chamber and its size has been approaching the cube root of population typical of first chambers. The Council of the European Union (CEU) is more akin to a second chamber and its size, in terms of qualified majority voting (QMV) votes, was approaching the size typical of second chambers at a given population. However, the Treaty of Nice has boosted the CEU to a size comparable to that of the European Parliament (EP), which may not be functional. Analogies to domestic first and second chambers suggest that the optimal size for the 27-country CEU might be 150 to 190 seats (Nice proposes 345), while that for the EP might be around 780 seats (Nice proposes 732).