Abstract
The role of the judge in court hearing involves decision making in several steps. Firstly, a set of facts provided by the plaintiff and the defendant must be validated in order to obtain the set of ultimate facts. Then, the substantive law and the procedural law are applied to infer to the final court decision. Not only the code law, but also the general principles of law need to be considered for the legal case. Therefore, we propose a legal expert system namely LegalEX that has ability to give correct court decision for user. LegalEX has three main features; Conflicted fact checking, legal principle checking and legal explanation. These features make LegalEX different from traditional legal expert systems since those systems require ultimate fact directly from user which is an error-prone process. Moreover, they use only code law as a knowledge base and disregard legal principle, which is significant to the final court conclusion. To gain acceptable from legal users in the law firm, LegalEX provides legal explanation as an output.