The literature on public goods has shown that efficient outcomes are impossible if participation constraints have to be respected. This paper addresses the question whether they should be imposed. It asks under what conditions efficiency considerations justify that individuals are forced to pay...

We study the impact of a nancial transactions tax on a market where financial institutions trade with each other. There are two main results: First, if all banks can honor their short-term obligations, a financial transactions tax is entirely neutral. Second, in a model with correlated...