Monetary unions which did not follow the path of fiscal rectitude are no longer with us.
In an article I published in 1997 ("The History of Previous European Currency Unions"), I identified five paramount lessons from the short and brutish life of previous - now invariably defunct - monetary unions:
(A) To prevail, a monetary union must be founded by one or two economically dominant countries ("economic locomotives"). Such driving forces must be geopolitically important, maintain political solidarity with other members, be willing to exercise their clout, and be economically involved in (or even dependent on) the economies of the other members.
(B) Central institutions must be set up to monitor and enforce monetary, fiscal, and other economic policies, to coordinate activities of the member states, to implement political and technical decisions, to control the money aggregates and seigniorage (i.e., rents accruing due to money printing), to determine the legal tender and the rules governing the issuance of money.
(C) It is better if a monetary union is preceded by a political one (consider the examples of the USA, the USSR, the UK, and Germany).
(D) Wage and price flexibility are sine qua non. Their absence is a threat to the continued existence of any union. Unilateral transfers from rich areas to poor are a partial and short-lived remedy. Transfers also call for a clear and consistent fiscal policy regarding taxation and expenditures. Problems like unemployment and collapses in demand often plague rigid monetary unions. The works of Mundell and McKinnon (optimal currency areas) prove it decisively (and separately).
(E) Clear convergence criteria and monetary convergence targets.
The current European Monetary Union is far from heeding the lessons of its ill fated predecessors. Europe's labour and capital markets, though recently marginally liberalized, are still more rigid than 150 years ago. The euro was not preceded by an "ever closer (political or constitutional) union". It relies too heavily on fiscal redistribution without the benefit of either a coherent monetary or a consistent fiscal area-wide policy. The euro is not built to cope either with asymmetrical economic shocks (affecting only some members, but not others), or with the vicissitudes of the business cycle.
This does not bode well. This union might well become yet another footnote in the annals of economic history.
The Concert of Europe, Interrupted