We analyse the projected future evolution of the distribution of voting power and related quantities under the qualified majority decision rule for the Council of Ministers of the EU, prescribed by the forthcoming EU Reform Treaty. Our projections are based on the demographic changes forecast by eurostat [4] for the period stretching from the present to the middle of the 21st Century. We use a method similar to the one we used in [6], [7], [8] and [9].

In a two-tier decision-making system such as the EU Council of Ministers, if the number of constituencies (member-states) is sufficiently large (say, 15 or more), Penrose’s Square-Root rule can be implemented to a high level of approximation by a simple weighted decision rule at the top level (the Council) with any given quota q smaller than the total weight. This leaves one degree of freedom: the value of q as a free parameter, to be determined by some additional condition. I (...) propose to survey and discuss critically the most important considerations for fixing this value – some of which have actually been used by theoreticians or practitioners: efficiency, transparency, sensitivity (total voting power of citizens), mean majority deficit, giving certain ‘privileged’ coalitions blocking status. Some of these considerations are reasonably compatible; others less so. Some kind of compromise is clearly needed. But which? This is essentially a political matter; but a political decision ought to be made in a theoretically enlightened way. (shrink)