Using UML for Modeling Procedural Legal Rules: Approach and a Study of Luxembourg's Tax Law

Many laws, e.g., those concerning taxes and social benefits, need to be operationalized and implemented into public administration procedures and eGovernment applications. Where such operationalization is warranted, the legal frameworks that interpret the underlying laws are typically prescriptive, providing procedural rules for ensuring legal compliance. We propose a UML-based approach for modeling procedural legal rules. With help from legal experts, we investigate actual legal texts, identifying both the information needs and sources of complexity in the formalization of procedural legal rules. Building on this study, we develop a UML profile that enables more precise modeling of such legal rules. To be able to use logic-based tools for compliance analysis, we automatically transform models of procedural legal rules into the Object Constraint Language (OCL). We report on an application of our approach to Luxembourg’s Income Tax Law providing initial evidence for the feasibility and usefulness of our approach.