That's not the point. By calling something "murder" even though it may have been legal, we are passing moral judgment on the act as well as the law and society

That's not the point. By calling something "murder" even though it may have been legal, we are passing moral judgment on the act as well as the law and society that tolerated it. To act as though someone using this term is simply unaware that it was legal, and needs a lesson on Roman law, is simply to be obtuse.