Before revision: The effective lower bound on a short term interest rate may not constrain a central bank's capacity to achieve its objectives if unconventional monetary policy (UMP) is powerful enough. We formalize this `irrelevance hypothesis ' using a dynamic stochastic general equilibrium model with UMP and test it empirically for  the United States and Japan using a structural vector autoregressive model that includes variables subject to occasionally binding constraints.
After revision: The effective lower bound (ELB) on the short-term interest rate irrelevant. We develop an empirical test of this `irrelevance hypothesis ' using a dynamic stochastic general equilibrium model with UMP and test it empirically for the United States and Japan using a structural vector autoregressive model that includes variables subject to occasionally binding constraints.