<Li> If a cause of action exists and the damage equals $50 while the cost of a wall is $100, the wall will not exist . Owner B may sue, win the case and the court will order Owner A to pay B $50 . This is cheaper than actually building the wall . Courts rarely order persons to do or not do actions: they prefer monetary awards . </Li> <Li> If a cause of action does not exist, and the damage equals $100 while the cost of the wall equals $50, the wall will exist . Even though B cannot win the lawsuit, he or she will pay A $50 to build the wall because the wall is less costly than the damages from the runoff . </Li> <Li> If a cause of action does not exist, and the damage equals $50 while the wall will cost $100, the wall will not exist . B cannot win the lawsuit and the economic realities of trying to get the wall built are prohibitive . </Li> <P> The Coase theorem considers all four of these outcomes logical because the economic incentives will be stronger than legal incentives . Pure or traditional legal analysis will expect that the wall will exist in both scenarios where B has a cause of action and that the wall will never exist if B has no cause of action . </P>

A coase solution to a problem of externality ensures that a socially efficient outcome is to