Romans 5:13

Until the law; before it was written, or communicated by Moses.

Sin was in the world; men committed it, and suffered the consequences; God treated them as sinners.

Sin is not imputed; it is not charged to men, or laid to their account; they are not held responsible and punished for it.

When there is no law; because sin is a transgression of a wise and good law. It follows that there was such a law binding on men before the time of Moses, and before any written revelation of the will of God was made to men. There was a law given to Adam from the mouth of God, by the violation of which sin entered, and death by sin. There was a law, too, written upon the hearts of all men as moral beings. Chap Romans 2:14-15. Of course there could be, and there was, transgression-violation of law. This was proved by the fact that there was death as universal as after the giving of a written law by Moses.