Romans 5:12
12 That is why, just as through one man sin entered into the world and death through sin, and so death spread to all men because they had all sinned. 13 For sin was in the world before the Law, but sin is not charged against anyone when there is no law. 14 Nevertheless, death ruled as king from Adam down to Moses, even over those who had not sinned in the same way that Adam transgressed, who bears a resemblance to the one who was to come.
In verse 13 it talks about the law, it is explained in
Jeremiah 31:33
But this shall be the covenant that I will make with the house of Israel; After those days, saith the LORD, I will put my law in their inward parts, and write it in their hearts; and will be their God, and they shall be my people