Abstract: We propose an object based system to represent domain knowledge and to store it in libraries for reuse, following a case based paradigm. Our tool is generic enough to model any problem which requires a legal qualification. This kind of problem requires cooperation between several knowledge domains (e.g., medical practice and legal evaluation). The proposed case model captures the necessary expert's knowledge. End users describe their cases in accordance with the expert's framework. The different elements composing the case are automatically stored in specific libraries with object indexes. Our project is totally object based for problem representation as well as for case indexation. The system retrieves similar cases to suggest solutions or to facilitate case modeling.