LKIF-Core Ontology

A core ontology of basic legal concepts

These pages serve as the download location for the LKIF-Core ontology, developed within the ESTRELLA project (IST-2004-027655).

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Base URI

LKIF Ontology base URI:

LKIF Extended base URI:



Download the latest version of the LKIF Core ontology directly from, or simply import the ontology from its base URI:

Loading the Ontology

The LKIF-Core ontology can be loaded locally (by unzipping the distribution in a local directory), or directly from our servers at It has been tested to work with TopBraid Composer, Protege 4.0 alpha and SWOOP. Please let us know if you experience any problems.


The LKIF-Core ontology is released under the GNU Lesser General Public License. For details about this license, please visit


Problems? Questions? Suggestions? Please contact Rinke Hoekstra at hoekstra[at] (replace the '[at]' with '@').




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The LKIF core legal ontology consists of 15 modules, each of which describes a set of closely related concepts from both legal and commonsense domains. In that sense, the LKIF core ontology is rather a library of ontologies relevant for the legal domain than a monolithic body of definitions. A glossary of the concepts and properties included in these modules can be found here. The online documentation provides a definition of each concept and property in the Manchester OWL syntax (See the co-ode website).

Abstract Concepts

The most abstract concepts are defined in five closely related modules: top, place, mereology, time and spacetime.

Basic Concepts

Basic-level concepts are distributed across four modules: process, role, action and expression.

Legal Concepts

These basic clusters are extended by three modules that form the legal ontology: legal action, legal role and norm.

Framework Modules

In addition to these legal clusters, two modules are provided that cover the basic vocabulary of two frameworks: modification and rules.

Core and Extended Ontology

Finally, the twelve modules of the abstract, basic and legal level are integrated in the LKIF-Core ontology module. This module does not provide any additional definitions, but functions as an entry-point for users of the ontology library. The two framework modules are accessible through the LKIF Extended ontology module. This module imports the LKIF Core module.


Known Problems

The problems which caused reasoners to be really (really) slow have been alleviated (see this post on the Pellet-Users mailinglist).


Version 1.0.3 - 20080501 - Minor Release
Version 1.0.2 - 20070322 - Major Bugfix Release
Version 1.0.1 - 20070223 - Bugfix Release
Version 1.0 - 20070202 - Initial Release