Looking at a Latin dictionary, both "ius" and "lex" seem to refer to about the same things. From usage during the Roman republic, I know that lex refers to a law enacted at a certain place by a certain imperium holder (e.g., lex publilia). However, I'm unclear what "ius" means. Reading the sources (livius, cicero, pulivius, dionisiyus of halicarnasos, etc.), it seems at times that they use the terms interchangedly, but still I feel there's a difference. I've had it suggested that ius is being used to refer to abstract law (e.g., in the case of http://en.wikipedia.org/wiki/De_jure). However, there are examples where it's just not so, namely - ius is being used for concrete laws, e.g. ius flavianum (cf. http://www.britannica.com/EBchecked/top ... -Flavianum), ius trium liberorum, Ius Regale Montanorum, etc. Could anyone point me to the right explanation ?