To ensure that the principle of liability – or as Walter Eucken put it: “Those who reap the benefits must also bear the costs.” – is also respected with regard to sovereign debt, the founding fathers of the euro had incorporated the no-bailout clause into the Maastricht Treaty.
It was the “linchpin of the construction of the euro”, as Hans-Werner Sinn wrote in one of his books. But with the institutions and rules in place before the crisis, simply letting a sovereign default happen proved to be risky for the financial stability in the euro area.