This paper discusses how to refine a given initial legal ontology using an existing MRD (Machine-Readable Dictionary). There are two hard issues in the refinement process. One is to find out those MRD concepts most related to given legal concepts. The other is to correct bugs in a given legal ontology, using the concepts extracted from an MRD. In order to resolve the issues, we present a method to find out the best MRD correspondences to given legal concepts, using two (...) match algorithms. Moreover, another method called a static analysis is given to refine a given legal ontology, based on the comparison between the initial legal ontology and the best MRD correspondences to given legal concepts. We have implemented a software environment to help a user refine a given legal ontology based on these methods. The empirical results have shown that the environment works well in the field of Contracts for the International Sale of Goods. (shrink)