Jamieson, Fausset & Brown

If there were no sin, there would be no death. Man's transgression of the law gives death its lawful power. strength of sin is the law--Without the law sin is not perceived or imputed (Rom 3:20; Rom 4:15; Rom 5:13). The law makes sin the more grievous by making God's will the clearer (Rom 7:8-10). Christ's people are no longer "under the law" (Rom 6:14).