SHYSTER and the Authorization of Copyright Infringement

The SHYSTER project is concerned with the development of a hybrid legal ex-
pert system: one which uses rule-based techniques to represent statute law and
case-based techniques to represent case law. A prototype has been developed, im-
plementing the case-based part of SHYSTER. This prototype allows a legal expert
to specify an area of case law using a specially-developed case law specication
language.
The model of legal reasoning which has been adopted for the development
of SHYSTER is explained, and the operation of the prototype is illustrated by
example. An area of case law (the meaning of \authorization" in the Copyright
Act ) is specied, and SHYSTER is made to generate opinions about real cases on
the basis of that specication. SHYSTER's legal opinions are compared with the
actual judgments in those cases.
SHYSTER's case-based system performs well in two quite different legal do-
mains, suggesting that SHYSTER's approach to case law may prove successful in
other areas of law. Avenues of future research are identied, and the manner in
which SHYSTER's case-based system will be linked with a rule-based system to
form a hybrid legal expert system is explained.