Artificial Intelligence and Law: Stepping Stones to a Model of Legal Reasoning

Abstract

This Comment discusses developments in the twenty-year-old interdisciplinary field of Artificial Intelligence (AI) and law. This field is important for both AI and law because it is directed at improving our understanding and modeling of legal reasoning. The AI and law projects discussed here are landmarks in this field.' A unifying theme of the projects is the goal to understand and model legal argument, a keystone of an overarching goal to understand and model legal reasoning. These goals require that we know first how to represent several types of knowledge, such as cases, rules, and arguments; second, how to reason with them, such as to manipulate precedents, to apply and make inferences with rules, and to tailor arguments to facts; and third, how to use them ultimately in a computer program that can perform tasks in legal reasoning and argumentation, such as analogizing favorable cases and distinguishing contrary ones, anticipating parries in adversarial argument, and creating artful hypotheticals. The projects constitute a coherent set of studies about key topics in AI and law: (1) reasoning with rules; (2) handling open-textured legal concepts; (3) reasoning with cases and hypotheticals; (4) integrating reasoning with rules and reasoning with cases; and (5) representing legal knowledge. The limitations of techniques for handling the first topic are addressed by the second, and the third topic addresses critical issues not covered at all by work on the first. The fourth integrates work on the first three, and the fifth provides underpinnings needed for all of them. The projects are some of the major accomplishments in AI and law, especially

Modeling law search as prediction

“…In her now classic definition of the program of research into artificial intelligence and law, Edwina Rissland sketched out the goals of the field and identified three related undertakings: first, to know "how to represent several types of knowledge, such as cases, rules, and arguments"; second, to know "how to reason with [those types of knowledge]"; and third, to know "how to use [those types of knowledge] ultimately in a computer program that can perform tasks in legal reasoning and argumentation" (Rissland 1990).…”

Arguments and cases: An inevitable intertwining

“…Stucky and Gidley point out that pragmatic considerations for legal argument have been overlooked in current models. See generally [Rissland, 1990] and [Stucky, 1986] for overviews of computational legal argument. Stucky also argues for a top-down and bottom-up control strategy for argument creation.…”

Case-based reasoning and its implications for legal expert systems

“…The CABARET program moves farthest in the direction of meeting Waterman's sug gestions (Rissland & Skalak 1991;Rissland 1990;Rissland & Skalak 1989). In CABARET, ambiguous predicates from statutes are annotated with positive and negative case examples.…”