By G.L.J. Jacobs on 2016-04-12 in Definitions,
A term used to denote the sharing of decision‐making powers between states in systems of international cooperation. Whereas unanimous decision‐making between states leaves sovereignty unscathed, given the right of any state to unilaterally veto decisions, pooling of sovereignty implies a departure from unanimous decision‐making. The most prominent system of international cooperation in which sovereignty is pooled is the European Union (EU). In a number of issue areas which have been defined in the treaty and subsequent treaty amendments, the member state delegates in the Council, one of the EU's legislative organs, decide by a qualified majority. Consequently, pooling creates the possibility that individual member states can be outvoted. The main reason why states choose to pool sovereignty is to reduce the likelihood of gridlock in policy areas where—on average—states expect to be better off by pooling sovereignty than by retaining the unanimity rule.
This has been the case particularly in the context of creating a European single market for goods and services. The introduction of qualified majority voting in these issues demonstrated that EU member states valued the benefits of the abolition of trade barriers more than those that would have been associated with retaining the right to veto. However, in policy areas which governments consider particularly sensitive for domestic or ideological reasons or where the potential gains from pooling sovereignty are uncertain, governments are likely to retain the right to veto (for example, foreign and security policy, and redistributive policies).