Attacking legal argument by examining stability of case citation with goal-dependent abstraction
Yoshiaki Okubo, Makoto Haraguchi · 1997
This paper proposes a computational method of attacking a case-based legal argument in a Hypo[l]-like system. For this purpose, we introduce a notion of stability of case citation. Our basic idea of stability is based on a reasonable requirement: if an old case is cited for a new case, the old case should be cited for each case similar to the new case as well. If a case citation satisfies the requirement, then the citation is said to be stable. We propose in this paper a computational method for attacking a legal argument from the viewpoint of stability of case citation. In order to examine whether a case citation is stable or not, we need to obtain cases similar to the new case. These are obtained with the help of Goal-Dependent Abstraction (GDA IS]). GDA is an algorithm for finding appropriate similarity between sort concepts according to our viewpoint. Based on the similarity found by GDA, we hypothetically create a set of cases similar to the new case. Then: each hypothetical case is examined whether we can cite the same old case for the hypothetical case. If we found that the old case cannot be cited for a hypothetical case, we attack the argument by pointing out unstableness of its case citation.