One of the most salient tasks in law is legal assessment, which concerns the problem of determining whether some case is allowed or disallowed given an appropriate body of legal norms. HARNESS is the name of a legal knowledge-based system that was developed in the context of the ESTRELLA project by the Leibniz Center for Law and the Corvinus University of Budapest. The general architecture of HARNESS allows for the implementation of multiple tasks, such as drafting, legal planning and argumentation. As legal assessment is viewed as the core of all legal reasoning tasks, we have taken this task to be the first one that HARNESS should be able to handle.

Legal Assessment requires three distinct types of knowledge. A domain ontology defines the concepts used as the basic building blocks for specifying case descriptions and norms. In HARNESS, the ontology is a specialisation of the LKIF Core ontology, which was developed within the ESTRELLA project as well. Individual case descriptions represent the facts that characterise an actual situation and is expressed in terms of the domain ontology. Normative knowledge describes the regulations that govern the situations we can express in terms of the domain ontology. Norms are expressed as generic situation descriptions in which a state or action is qualified as undesirable, permitted or prescribed.

To assist users in the task of assessing an individual case, a Protégé plug-in was developed that is able to deal with all of the different knowledge components automatically, using standard OWL 2 DL reasoning. After the reasoning is done, a “final verdict” is presented to the user. If multiple norms apply to the individual case, the plug-in generates a final decision based on the principle of lex specialis, where the most specific norm takes precedence over a more general norm. The plug-in also generates an explanation on why it reached the specific verdict.


  • “Developing HARNESS: Towards a Hybrid Architecture for LKIF” (Deliverable 4.6)
  • Saskia van de Ven, Joost Breuker, Rinke Hoekstra, Lars Wortel, and Abdallah El-Ali. Automated legal assessment in OWL 2. In Legal Knowledge and Information Systems. Jurix 2008: The 21st Annual Conference, Frontiers in Artificial Intelligence and Applications. IOS Press, December 2008.
  • Saskia van de Ven, Rinke Hoekstra, Joost Breuker, Lars Wortel, and Abdallah El-Ali. Judging Amy: Automated legal assessment using OWL 2. In Proceedings of OWL: Experiences and Directions (OWLED 2008 EU), October 2008.


A prototype version of HARNESS, including some documentation and examples can be downloaded directly: