Exploring Relevant Parts Between Legal Documents Using Substructure Matching

Takahiro Komamizu, Kazuya Fujioka, Yasuhiro Ogawa, Katsuhiko Toyama

Abstract: Legal documents are typically hierarchically structured. This paper focuses on ordinances and rules (OR documents for short) in the local governments, which are designed for social lives under the governments. OR documents are composed of provisions for social lives in various aspects such as healthy development of youths and landscape preservation. OR documents in different local governments share common provisions but also include different provisions depending on their social situations. There is a large demand on helping governmental officers draft OR documents, especially searching “relevant parts” of OR documents. To help drafting OR documents, this paper designs the relevancy of OR documents with two basic measurements; matching ratio and provision commonality. Based on the relevancy, this paper develops a structured document search algorithm for OR documents. Experimental evaluation on real OR documents in Japan demonstrates that the proposed algorithm successfully discovers relevant parts of OR documents.