Take a standard New Keynesian macro model. Assume it sometimes gets stuck in a ZLB liquidity trap, where monetary policy can't work.
There is a very simple solution: use fiscal policy.
Government spending should be cut whenever the economy is not in a liquidity trap. That is the clear policy implication of New Keynesian macroeconomic models.
I am very pleased to see that Canada's Conservative government is currently following that New Keynesian policy recommendation, and is cutting government spending now that the Canadian economy is no longer at the ZLB. All New Keynesians will applaud this sensible policy. Any opposition to this use of fiscal policy must be ideological.