This essay offers a sympathetic, utilitarian critique of Louis Kaplow's famous argument for legal retroactivity in his 1986 article, "An Economic Analysis of Legal Transitions." The argument, very roughly, is that the prospect of retroactivity is desirable if citizens are rational because it gives them a desirable incentive to anticipate legal change. My central claim is that this argument trades upon a dubious, objective view of probability that assumes rational citizens assign the same probabilities to states as rational governmental officials. But it is subjective, not objective probabilities that bear on rational choice, and the subjective probabilities of rational citizens can diverge from rational officials'. I imagine a simple case in which a single Social Planner structures both transition policy and substantive law in some domain. The legal change that the Planner anticipates she would enact in response to a given set of events, and the legal change that the Planner believes one or another citizen believes she (the Planner) will enact in response to those events, can differ. And this means, in turn, that there can be incentive costs to a retroactivity regime as well as a prospectivity regime, even if all actors are fully rational. The utilitarian case for retroactivity is more contingent than Kaplow thinks.
Matthew D. Adler, Legal Transitions: Some Welfarist Remarks, 13 Journal of Contemporary Legal Issues 5-28 (2003)
Library of Congress Subject Headings
Well-being, Social welfare, Law, Retroactive laws, Utilitarianism, Consequentialism (Ethics)