TRIAL: A Legal Reasoning Experimental System 

Objectives 

We deal with a legal reasoning problem as an application of knowledge base 
and knowledge representation technologies to a legal field. Legal reasoning 
consists of three components, that is, fact recognition, statutory interpreta-
tion, and statute application. Since it is hard to treat fact recognition at the 
present level technology, TRIAL in Quixote aims to perform statutory inter-
pretation as well as statute application, especially analogical interpretation 
which uses relevant existing precedents. 

Therefore, given a new case, TRIAL gives possible judgments by using ex-
isting precedents which are similar to the new case, and constructs arguments 
that lead to a judgment. 

Advantages of Quixote

For the purpose of analogical interpretation, the following Quixote-support-
ed features are useful: 

By type hierarchies, the taxonomy hierarchies of legal concepts can be 
dealt with easily in TRIAL. 

By conclusions with assumptions, TRIAL can give judgments with as-
sumptions. This also means that missing information can be supplied. 

Furthermore, the following features are helpful in offering an environment 
for thought experiments with legal reasoning: 

By queries with hypotheses and module hierarchies, hypothetical queries 
can be asked experimentally in TRIAL. 

By a solution explanation feature, TRIAL can construct arguments for 
verification of judgments. 


Outline of Demonstration 

We demonstrate a process in which experts or semi-experts construct the 
desired argument by application of TRIAL to the  (or death from 
overwork) problem. 

They gain a goal judgment by asking TRIAL a hypothetical query. 

They verify whether the arguments constructed by TRIAL are adequate. 



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