Should a subset of member states of a federation be allowed to form a sub-union on some policy issue? When centralization is not politically feasible, allowing an enhanced cooperation agreement among a subset of countries permits the latter to gain benefits which would otherwise be lost....

The paper argues that economic integration causes problems for the labor market of high-wage countries due to cross-border labor mobility and the accompanying increase in labor supply. Empirical evidence is provided from an analysis of regional labor market effects of German re-unification. In...