Before/After Law

Abstract

Should the Law be forward- or backward-looking? For some the answer is clear:  Because Economics is forward-looking, the Law should be as well. Undergirding this reasoning is the fundamental distinction between ex ante and ex post. Conventionally, the distinction turns on different temporal vantage points:  ex ante/post refers to something before/after an occurrence. Few, however, realize that the distinction also can be applied at a fixed point in time and turn on different epistemological states:  ex ante/post in this sense refers to whether something is known/unknown, which tracks the distinction between certainty/risk.

This paper critically examines these two variants of the ex ante/post distinction. Current applications of the distinction fail to realize that both variants presume some kind of sameness, either across time (i.e., diachronic) or possible outcomes (i.e., synchronic). Neither variant is exclusive of or superior to each other; they simply reflect different things and serve different functions. Iconic cases are then examined to demonstrate how the ex ante/post distinction has been misapplied conventionally and can be redeployed using the diachronic-temporal and synchronic-epistemological framework presented here to generate robust results.

Keywords: Ex Ante, Ex Post, Risk, Uncertainty, Diachronic Sameness, Synchronic Sameness