With the spectre of a recession looming in the eurozone (and elsewhere), the policy question arises as to how much leeway do the fiscal authorities in the eurozone have to follow counter-cyclical fiscal policies aimed at providing some stimulus to the economy.

The Tobin tax idea, developed during the 1970s as a tax on foreign-exchange transactions, has found its way back into the academic and policy debates, since the Copenhagen World Social Summit and the G7 Summit in early 1995 at the latest. At both events, proposals were put forward to impose a...