This article aims to provide a systematic model for determining equivalents in legal translation based on comparative law methodology. Because of the inherent incongruity of legal terms between different legal systems, legal translators need to search for functional equivalents in the target legal system that convey similar concepts with the source legal system, and determine the acceptability of such equivalents. By adopting Šarčević (1997), this article presents a methodology for measuring the degree of functional equivalence and reliable means of compensating for terminological incongruence and other alternative equivalents in the case of low acceptability of functional equivalents. In order to demonstrate the process of determining functional and other linguistic equivalents, this article analyzes the English translation of “특수관계인(teok-su-gwan-gye-in)”, one of the complicated legal terminology in Korean law. The findings show that only partial or non-equivalence exists between the Korean term and its functional equivalent candidates, which requires other linguistic equivalents such as literal equivalents and borrowing supported by clarification strategies.