The chairman of Britain's Financial Services Authority, Adair Turner, has an op-ed piece in the Financial Times floating the following idea: "It would, for instance, be possible to set a rule that no board member or senior executive of a failing bank will be allowed to perform a similar function at a bank unless they can positively demonstrate to the regulator that they warned against and sought to reduce the risk-taking that led to failure."
It would be "possible" to set similar rules for regulators and central bankers, too, but Lord Turner doesn't suggest that. Imagine trying to run a bank amid the proliferation of cover-your-rear type memos that such a rule would spawn.