John Chrysostom

The phrase "till the Law" some think he used of the time before the giving of the Law-that of Abel, for instance, or of Noah, or of Abraham-till Moses was born. What was the sin in those days, at this rate? some say he means that in Paradise. For hitherto it was not done away, (he would say,) but the fruit of it was yet in vigor. For it had borne that death whereof all partake, which prevailed and lorded over us. …

Homily on Romans X ↗

Theophylact of Ohrid

The Apostle wants to prove that even those who did not eat from the forbidden tree and did not sin like Adam were, on account of his sin, also counted as having sinned and died. He proves this as follows: sin reigned before the giving of the law, that is, even before the law. But what sin was this? Was it sin from transgression of the law? But how could there be such sin when there was no law? Sin is imputed when there is a law, and people who transgress the law are necessarily called sinners.

Commentary on Romans ↗

Thomas Aquinas

After tracing the origin of sin and death and their entry into the world, the Apostle now clarifies what he has said. First, he explains his statement; second, he clarifies the comparison he suggested, when he said: wherefore as by one man (Rom 5:12); third, he explains it, at who is a figure of him who was to come. Now he had stated that sin and death passed on to all men. Here, in line with Augustine's exposition, he intends to explain this by the fact that sin remained even under the law, implying that it was unable to expel it. …

Commentary on Romans ↗