In many domains concept definitions undergo change on a relatively frequent basis. Especially in law, such changes can have far reaching consequences. Existing ontology versioning techniques often do not consider that old and new definitions may need to co-exist side by side in a knowledge base, or they require non-standard language extensions. In this paper we present a description logic based representation that allows us to model and switch between varying definitions of concepts in a single OWL ontology. We show how this representation can be used to model complex versioning schemes in law.