Unconventional tools deployed by central bankers from Frankfurtto Washington to mitigate the economic fallout of the financialcrisis may be conventional when the time comes to combat the nextdownturn.

The Federal Open Market Committee (FOMC) is already discussingthe issue while other central bankers and economists in developednations debate whether to holster emergency policies—bond buying,targeted credit programs, and negative interest rates—or make thempart of their everyday armories.

The shift beyond a short-term interest rate as the main lever ofmonetary policy could force investors, consumers, and businesses tomake sense of a world with multifaceted, sometimes arcane policies.Toolkits expanded since the crisis seven years ago are encounteringresistance from lawmakers and others who argue central bankers havegone beyond their mandates.