Like an Apollo moon shot, the pending financial regulatory overhaul is a noble, necessary undertaking. Yet its success depends on so many intricate, human systems—panels, oversight committees and refashioned bureaucracies—that we should prepare for multiple malfunctions along the way. The new law will hurtle us somewhere, just probably not where Congress intends. That seems especially so for a pending overhaul of the credit-ratings agencies, which famously flubbed their duties during the mortgage boom last decade.