After all, the euro area is not the only entity covering thousands of banks in which centrally controlled supervision is in place. To what extent is this likely to represent an intrusion into what should properly belong to a national policy arena? I am doubtful that there is any intrusion at all.
Safety and soundness of banking is a common goal of bank supervision: non-market goals of public banking policy can be effected through taxation or other means. Assessing creditworthiness and balance sheet risks is not really something that I believe has much room for national exceptionalism.