You can make quite a resounding case for a Pigovian tax if you study economics. This is a tax that gets people to pay the full social cost of the good, and not just the private cost. This principle of getting the polluter pay provides a case for alcohol tax, Carbon Tax, congestion charges, and tobacco tax.

However, whether they implement these policies depends on whether there is political support.

Who runs the economy: Economists or politicians?

Another interesting case is the relationship between fiscal policy and monetary policy.

In the US and UK, fiscal policy is relatively tight, given the state of the economy. As a result, this falls to Central Banks to follow an expansionary monetary policy to counterbalance the dearth of fiscal policy. Central Bankers need to adapt monetary policy if politicians follow tight fiscal policy.