Qualified Majority Voting

Qualified Majority Voting (QMV) is the official European Union (EU) term for the decision rule employed by its Council of Ministers (CM) for most of its decisions. Basically, QMV is a weighted decision rule: each EU member state is assigned a weight (a number of votes); and for a bill to pass, the total weight of the member states voting for it must equal or exceed a set quota (also known as the threshold), constituting a specified supermajority of the member states' votes.

The weights and quota were first set for the original six members in the 1957 Treaty of Rome, and up until the 2001 Nice Treaty they had to be reset with each successive enlargement of the EU (1973, 1981, 1985, and 1995). So far there has been no explicit general formula prescribing how the weights and quota should be set. Rather, with each enlargement the allocation was renegotiated ad hoc. Nevertheless, there was a fairly stable implicit pattern. On all five pre-Nice occasions, weights were allocated according to a so-called degressive (or subproportional) principle, whereby the more populous states were assigned greater weights, but less than proportional to their population size. The quota was chosen as the integer closest to 71% of the total weight.

However, in view of the prospective enlargement of the EU from 15 members in 1995 to 27 during the following 12 years, the Nice EU Intergovernmental Conference of December 2000 thoroughly redesigned the QMV rule. The new QMV provisions (stated in the Treaty of Nice of February 26, 2001, which came into force in May 2004 when 10 new member states joined the EU) differ from the previous QMV rules in three respects.

First, the degressive weighting was redesigned by allocating to the 15 existing members and the 12 then-prospective members a new set of weights. Second, the quota of this decision rule was raised in the 27-member scenario to nearly 74% of the total weight (255 votes out of 345). Third, in addition to the usual quota condition for passing a bill, two further conditions were imposed: those member states supporting the bill must be a majority of the members, and their population must be at least 62% of the total population of the EU.

However, detailed computation shows that the effect of these two additional conditions on the members' voting powers is very small indeed. This is because out of the huge number of possible voting configurations (divisions of the CM as between yes and no voters) there are very few that meet the quota of the degressive weighted rule, but fail to satisfy the two additional conditions. The second change made at Nice, raising the quota from the traditional 71% to 74% for the 27-member scenario, seems almost trifling. But in fact it is momentous, because potentially it makes passing bills considerably more difficult.