Though congestion tolls can increase social welfare, the public often opposes them. One explanation
for the opposition is that a road user views a congestion toll as punishment for the damage he causes
others. Since a user suffers from congestion, he believes that he has already suffered some punishment
and therefore it is unfair or unjust to impose a toll in addition. We assume that a person views a
congestion toll as unjust if the toll exceeds the difference between the congestion externality a road user
generates on others and the uncompensated externality he suffers from others. We explore the
implications of such a view. We illustrate how to determine the toll that satisfies this criterion of justice
and how the socially optimal toll violates the criterion. We examine how the just toll varies with the
parameters of the model. We discuss the implications of alternative definitions of justice and possible
extensions of the basic model considered.
