On the one hand, higher capital requirements reduce bank leveraging, the risk of bank failures and the implicit subsidies given to banks on account of deposit insurance schemes backed by the government and ultimately the taxpayer. On the other hand, excessively high capital requirements may unduly curtail banks’ ability to provide credit to the economy.
According to this line of reasoning, this "umbrella" could not be the central bank, since the latter is traditionally in charge of supervising monetary organisations. I will not embark upon a thorough analysis of this issue now.