The legal translator of common law documents must consider that it is primarily based on casuistry. In fact, common law legal systems are characterized by casuistry and the translator more versed in civil law must be careful to retain the intention underlying this casuistry, as opposed to cases whose communicative purpose is different. This article examines the casuistry of the common law in contrast to the opposed tendency – generalization – found in civil law countries. That contrast remains although today both legal systems regard the general principles of law as a source of law. Furthermore, we distinguish two types of casuistry, the one used by way of example and the one used in order to provide a comprehensive list of cases.