A key element for understanding the possible developments of the sovereign debt crisis relates to several rounds of non-standard interventions, ranging from the first Security Market Programme to the enhanced Long Term Refinancing Operations, launched by the European Central Bank from May 2010 to March 2012 as a reaction to the exceptional circumstances prevailing in financial markets. In the meantime, the other European institutions prepared and approved a number of legislative changes, intended to enhance the common economic governance and budgetary surveillance. This paper looks at the implications of the “non-standard measures” for the institutional role of the Central Bank in the context of the European Treaty, and examines the new legal acts as instruments to correct and prevent imbalances. The lessons from the Greek case point to more general elements of weakness in the Union, which can only be addressed by an integrated set of significant changes in the EU architecture. Specific attention should be paid to the role played by the rating agencies, and to the opportunity to foresee appropriate supervision by public authorities over them: taking into account that the current regulation seems far from satisfactory, and reforms in line with those enacted in the US would greatly help. The need for solid and sustainable fiscal policies remains key, together with appropriate budgetary and macroeconomic surveillance. [...]