Central to ongoing debates over the desirability of monetary unions is a supposed trade-off, outlined by Mundell [1961]: a monetary union reduces transactions costs but renders stabilization policy less effective. If shocks across countries are sufficiently correlated, then, according to this...

The desirability of fiscal constraints in monetary unions depends critically on whether the monetary authority can commit to follow its policies. If it can commit, then debt constraints can only impose costs. If it cannot commit, then fiscal policy has a free-rider problem, and debt constraints...