The result model of precedent

Legal Theory

Volumn 10, Issue 1, 2004, Pages 19-31

  Horty, John F ^a  

^a UNIVERSITY OF MARYLAND   (United States)

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[No Author keywords available]

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EID: 33749454697     PISSN: 13523252     EISSN: 14698048     Source Type: Journal    
DOI: 10.1017/S1352325204000151     Document Type: Article

References (16)

1. Larry Alexander, Constrained by Precedent, 63 S. CAL. L. REV. 1-64 (1989); many of the arguments from this long paper are summarized in Larry Alexander, Precedent, in ACOMPANION TO PHILOSOPHY OF LAW AND LEGAL THEORY 503-513 (Dennis Patterson, ed., 1996).
2. For the purpose of this brief exposition, I shall speak as if the rule underlying a decision is plain, ignoring the extensive literature on methods for determining the rule, or ratio decidendi, of a case. I shall also speak as if a case always contains a single rule, ignoring situations in which a judge might offer several rules for a decision, or in which a court reaches a decision by majority, with different judges offering different rules, or in which a judge might simply render a decision in a case without setting out any general rule at all.
3. Alexander, Precedent, For the purpose of this brief exposition, I shall speak as if the rule underlying a decision is plain, ignoring the extensive literature on methods for determining the rule, or ratio decidendi, of a case. note 1, at 29-30. In addition to this first description of the result model, Alexander provides two additional formulations-one of which relates the model to some of Dworkin's ideas, the other to the precedent court's reasoning-and then argues that all three formulations are equivalent. I concentrate here only on the first, or a fortiori, formulation, which I take as canonical.
4. See Alexander, Precedent, addition to this first description of the result model note 1, at 45-47 for his arguments attributing the result model to these various writers.
5. Alexander, Precedent, for his arguments attributing the result model to these various writers. note 1, at 5.
6. Alexander, Precedent, Precedent note 1, at 34-35.
7. These two arguments are found in Alexander, Precedent, Precedent note 1, at 34-37.
8. Alexander, Precedent, These two arguments are found in Alexander note 1, at 36-37.
9. Since the current task is to define a pure result model of precedent, we ignore any rules that may have figured into the decision in precedent cases.
10. See Kevin Ashley, Toward a Computational Theory of Arguing with Precedents: Accommodating Multiple Interpretations of Cases, in PROC. SECOND INT'L CONF. ARTIFICIAL INTELLIGENCE & LAW (ICAIL-89) 93-110 (1989); and Kevin Ashley, MODELING LEGAL ARGUMENT: REASONING WITH CASES ANDHYPOTHETICALS (1990); see also Edwina Rissland, Artificial Intelligence and Law: Stepping Stones to a Model of Legal Reasoning. 99 YALE L. REV. 1957-1981 (1990), for an overview of research in Artificial Intelligence and Law that places this work in a broader context. The factor-based case representation has been developed most extensively in the domain of trade secrets law, where Vincent Aleven, Teaching Case-Based Argumentation through a Model and Examples (1997) (unpublished Ph.D. thesis, University of Pittsburgh) has analyzed 147 cases in terms of a factor hierarchy that includes 5 high-level issues, 11 intermediate-level concerns, and 26 base-level factors. The resulting knowledge base is used in an intelligent tutoring system for teaching elementary skills in legal argumentation, which has achieved results comparable to traditional methods of instruction in controlled studies; see Vincent Aleven & Kevin Ashley, Evaluating a Learning Environment for Case-Based Argumentation Skills, in PROC SIXTH INT'L CONF. ARTIFICIAL INTELLIGENCE & LAW (ICAIL-97) 170-179 (1997). Of course, the formal treatment sketched in the text abstracts considerably from this detailed representational work, and in particular the idea that legal factors are organized into a hierarchy is missing entirely; some of the formal problems involved in reasoning with factor hierarchies are discussed in John Horty, Precedent, Deontic Logic, and Inheritance, in PROC. SEVENTH INT'L CONF. ARTIFICIAL INTELLIGENCE & LAW (ICAIL-99) 63-72 (1999).
11. See, Precedent, Toward a Computational Theory of Arguing with Precedents: Accommodating Multiple Interpretations of Cases note 1, at 42-44. There is also a third argument, at 37-42, but this argument is directed against some of Dworkin's proposals, motivated by the idea that these are equivalent to the result model; I ignore this third argument, since I am here considering only the a fortiori formulation of the result model.
12. Alexander, Precedent, Precedent note 1, at 43.
13. Arthur Goodhart, Determining the ratio decidendi of a Case, 40 YALE L.J. 161-183 (1930), at 169.
14. See Jonathan Dancy,MORAL REASONS (1993), for arguments in favor of this view; and Brad Hooker & Margaret Little,MORAL PARTICULARISM (2000), for a collection of essays on the topic.
15. This example is due to Henry Prakken & Giovanni Sartor, Modelling Reasoning with Precedents in a Formal Dialogue Game, 6 ARTIFICIAL INTELLIGENCE & L. 231-287 (1998), who develop a model of reasoning with polarity-free factors.
16. There are different ways of defining similarity measures among factor sets, and I do not mean to take a stand on this issue. The suggestion in the text is reminiscent of a well-known proposal by Amos Tversky, Features of Similarity, 84 PSYCHOL. REV. 327-352 (1977); Ashley's work concentrates, by contrast, only on factor overlap.