Towards a Scalable Architecture for Legal Ontologies Integrated into Digital Twins of Administrative Law

Administrative-law provisions are still published almost exclusively in natural language, forcing every stakeholder to translate identical rules into bespoke code bases—a practice that invites inconsistency, hampers transparency, and inflates maintenance costs. Recent work on Digital Twins for Administrative Law (DTAL) suggests that legislation be issued together with machine-readable ontologies and executable logic, yet guidance on how to architect such systems remains scarce. In this work we propose a layered reference architecture that separates (i) the natural-language statute, (ii) a core ontology expressed in OWL, (iii) a configuration layer for mutable policy parameters, and (iv) an executable-rule layer exposed through a RESTful and MCP façade. Grounded in design science research, we implemented a proof-of-concept twin of the Upper-Austrian tourism-levy statute and qualitatively evaluate the twin with legal, software, and public-administration experts. Early results suggest that ontology-driven twins can reduce duplicate implementations, streamline updates, and enhance legal certainty, thereby strengthening the Rule of Law in automated decision-making.

Keywords: Legal Ontologies, Semantic Interoperability, Automated Decision-Making, Digital Twins