Case-based reasoning in a rule-governed domain

A discussion is presented of the problem of reasoning with cases in a domain governed by rules, in particular, the problems of interpreting the meaning of terms (statutory predicates) used in the rules and combining case-based reasoning (CBR) with other modes of reasoning, such as rule-based and model-based reasoning. Terms used in statutes are typically underdefined in the statute and inherently open-textured and thus require precedent-based reasoning to interpret their meaning for particular fact situations. In such domains one needs to combine reasoning about the rules (statutes) with the precedents that concern them. A description is given of the precedent-based case-based reasoner TAX-HYPO, which operates in the statutory domain of tax law. TAX-HYPO is a derivative system of an earlier CBR system, HYPO, which operated in the common law domain of trade secret law. The authors describe CABARET which is an environment to support the building of precedent-based CBR systems like HYPO and TAX-HYPO, as well as experimentation with mixed-paradigm systems involving CBR