In Romans 3:19, how does Paul use the word 'law'?
In Romans 3:19, Paul uses 'the law says' to refer specifically to the Ten Commandments, the moral law. But when he speaks of 'them who are under the law,' he means the whole system of law—civil, ceremonial, and moral—given to Israel.
Les explains that the Jew, the nation of Israel, was under the law, and God gave them the law printed on the tables of stone. The whole system of law included the religious and ritual system, the sacrifices, the priesthood, and the civil law, but at the heart of the law were the Ten Commandments. In Romans especially, Les says we must be careful whether a reference means the Ten Commandments or the whole system of law. So in Romans 3:19, when Paul says 'the law says,' he is talking about the Ten Commandments, the moral law, while 'them who are under the law' refers to the whole system of law.