Resolving Definitional Ambiguity in Legal Language: A Logical Approach to Consistent Judicial Outcomes

Ambiguity in legal language poses a critical challenge in statutory interpretation, where even minor differences in wording may result in conflicting interpretations and inconsistent judicial decisions. While legal definitions aim to provide precision, they are often context-dependent, vary across documents, and carry different levels of authority depending on their source and scope. This issue is especially prominent in statute-based systems such as Vietnam’s, where hierarchical legal documents coexist with unique institutional characteristics. To address this, we previously proposed the DeCoRA framework as a baseline approach to resolving definitional ambiguity. However, its reliance on oversimplified methods limits its effectiveness. In this paper, we introduce an extended version, DeCoRA_v2, which builds on ASPIC+ by introducing principle-based argument comparison and information admissibility mechanisms tailored to resolving definitional ambiguity in legal reasoning. By applying our approach to illustrative examples, we demonstrate its effectiveness in resolving definitional ambiguity and promoting more consistent judicial reasoning.