Comparative Causation

27 Pages Posted: 10 Dec 2001

See all articles by Francesco Parisi

Francesco Parisi

University of Minnesota - Law School; University of Bologna

Vincy Fon

George Washington University - Department of Economics


As Calabresi (1996) pointed out, no consideration has been given in recent legal and economic literature to the idea of distributing an accident loss among a faultless tortfeasor and an innocent victim on the basis of the relative causal contribution of the parties to the loss. This criterion of apportionment of liability, which we call comparative causation, is the object of this paper. We present a brief intellectual history of the principle of comparative causation and provide a positive economic model. In order to identify structural features of the rule, we first consider a rule of pure comparative causation where liability is allocated on the basis of causation, regardless of parties' fault. The economic model brings to light some interesting features of the rule, but also unveils the limits of such a criterion of liability with respect to induced activity and care levels. The paper then extends the economic model to consider the workings of the comparative causation rule in conjunction with negligence rules. Applying the comparative causation rule under a negligence regime induces a combination of incentives that no known liability rule provides.

Suggested Citation

Parisi, Francesco and Fon, Vincy, Comparative Causation. American Law and Economics Review, Vol. 6, No. 2, Fall 2004, George Mason Law & Economics Research Paper No. 01-30, Available at SSRN: or

Francesco Parisi (Contact Author)

University of Minnesota - Law School ( email )

229 19th Avenue South
Minneapolis, MN 55455
United States

University of Bologna ( email )

Piazza Scaravilli 1
40126 Bologna, fc 47100

Vincy Fon

George Washington University - Department of Economics ( email )

2115 G Street, N.W.
Monroe Hall, #366
Washington, DC 20052
United States
202-994-7580 (Phone)
202-994-6147 (Fax)

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