Guess what? The British actually had this! Not even kidding. From the July 23rd Economist:
Just what health care reform in this country so desperately needs. Is Mr. Osborn available?
George Osborne, the Conservative shadow chancellor of the exchequer [...] says an incoming Tory government would ask competition authorities to investigate this concentration. His plans stop short, as do [current Labour Party chancellor of the exchequer Alistair] Darling’s, of cutting big and dangerous banks down to manageable size.
Both men hope that added capital requirements, foisted on big firms by their supervisors, will make the cost of unwieldy size and over-risky behaviour prohibitive. But this puts a heavy responsibility on the regulator, which must identify and quantify the risks in order to levy the charges. This was the regulatory Achilles heel that led to the present crisis.
How much better, laments a Bank of England veteran, was the “Willie Osborn test”. Bankers wishing to do something “innovative” first had to explain it to Mr Osborn (no relation) in the supervision department. If he did not understand it, then it was too complex.