The proposed European bank-deposit scheme could not be the saviour of the eurozone. Even if an unlimited guarantee were politically feasible, it would still lack credibility

With the risk of a bank run in the eurozone rising, there has been talk amongst EU policymakers of creating a European-wide bank deposit guarantee scheme.

Over the past week, members of the European Commission and European Central Bank president Mario Draghi have all spoken out in favour of such a scheme. This would be a form of fiscal union through the back door and therefore a step in the right direction for the eurozone, but it is very unlikely to be politically feasible or credible.

Though European policymakers are in favour of a European-wide deposit guarantee scheme, Germany most certainly is not. Even if its government were willing to sign Germany up to backstopping bank deposits in the southern European countries, the German Constitutional Court would find it illegal on the basis that Germany’s financial exposure would be unlimited in nature.

To get around this problem, a cap could be placed on the European-wide bank deposit guarantee scheme, with only deposits up to a certain level guaranteed. If the cap is not high enough – and history has shown that in the eurozone crisis response, the figures are never high enough – then it would most likely exacerbate a bank run as depositors rushed to withdraw their cash above the established threshold.

Even if an unlimited European-wide bank guarantee deposit scheme were politically feasible, it would probably lack credibility.

Total eurozone deposits amount to roughly €15trn. The European bailout funds – the European Financial Stability Facility and the European Stability Mechanism – together total €0.5trn. Granted, not all deposits will need to be guaranteed as we are very unlikely to see a bank run in the likes of Germany and Finland. But still, the gap is sufficiently large to make anyone sceptical that an unlimited deposit guarantee scheme really could backstop all eurozone deposits.

The only way this gap could be filled is if the ECB were willing to print a wall of money to plug the hole. As I have argued several times already, it is extremely unlikely the ECB will fire up the printing presses in an unlimited fashion.

More importantly, depositors are withdrawing their money from peripheral eurozone banks because they are concerned about their savings being redenominated and devalued away should their country exit the eurozone. A European-wide deposit guarantee scheme cannot guarantee against a redenomination.

We have seen that national bank deposit guarantee schemes have failed to stem the ‘bank jog’ currently occurring in the weaker eurozone countries. A European-wide bank deposit guarantee would be an improvement, but even if it could be agreed by European leaders, it may on its own still fail to stop a bank run.

Megan Greene is head of European economics at Roubini Global Economics. This post first appeared on the Euro Area Debt Crisis blog