SHYSTER-MYCIN: A Hybrid Legal Expert System

Abstract

SHYSTER-MYCIN combines a case-based legal expert system (SHYSTER) with a rule-based expert system (MYCIN) to form a hybrid legal expert system. MYCIN's reporting has been improved for use with SHYSTER-MYCIN to provide more useful information about the system's conclusions. SHYSTER-MYCIN's output was tested against that of a group of lawyers, not expert in the test domain (Australian copyright law). This allowed the system's reasoning, rather than its depth of knowledge, to be tested. Testing indicates that SHYSTER-MYCIN's approach to the law - using a rule-based system to reason with legislation and a case-based system to reason with cases - is appropriate.

Keywords: law, legal, expert systems, artificial intelligence, jurisprudence, legal reasoning, hybrid, evaluation, testing, MYCIN, SHYSTER