The increasing road traffic in Sweden will require investments in the infrastructure that the tax withdrawal of today will not allow according to a new government report, SOU 2006:33. An existing willingness to pay for those investments has therefore become an alternative to increases in taxation to be able to cover the costs. A proposal to let the willingness to pay, alternatively increases in taxation that act proportional, decide how a cost is distributed can be said to be related, but not fully correspond, with different theories of justice described by Robert Nozick and John Rawls. It can therefore be interesting to see how the two different theories of justice are edified and how they distribute a joint cost. The aim of the first part of the thesis is to present and criticize Rawls' and Nozick's theories of justice in a common formulated economic model.