ODRL Policy Comparison Through Normalisation

A team of computer scientists has introduced a formal method to tackle a core problem in digital rights management: the overwhelming complexity of the ODRL (Open Digital Rights Language) standard. ODRL is widely used to encode permissions, prohibitions, and obligations for digital assets, but its flexibility means the same rule can be expressed in countless ways. This creates a major barrier for automated systems trying to determine if two policies—say, from a content licensor and a user—are compatible or in conflict. The new research, accepted at the European Semantic Web Conference (ESWC 2026), provides a solution by defining a mathematical normal form for ODRL.

The proposed algorithm systematically transforms any ODRL policy into this standardized format. It works by breaking policies down into minimal components, converting prohibitions into equivalent permission statements, and simplifying complex numerical and logical constraints. The authors prove their method is semantics-preserving, meaning the normalized policy has the exact same legal meaning as the original. While the worst-case size of the normalized policy can grow exponentially with the number of attributes, this process fundamentally reduces the problem of policy comparison to a straightforward check for textual identity between two simplified rule sets. This breakthrough enables interoperability between systems that use different fragments of ODRL and paves the way for reliable automated compliance engines.