In Rom. 7 the Apostle enters largely into the question of the nature of law; taking up and proving his previous passing notice of law, such as "by the law is the knowledge of sin" (Rom. 3:20); "We establish the law" (Rom. 3:21); "Sin shall not have dominion over you, because ye are not under law" (Rom. 6:14).
I apprehend that "law" (Rom. 7:4) must be taken in the same comprehensive sense as in these passages, and therefore necessarily includes the moral law. The doctrine of the sixth chapter is that nothing short of death justifies from sin, and that we must have died unto sin in order to live to God; and that we have died to sin judicially in Christ (Rom. 6:2), cp. with Rom. 6:10.
In Rom. 7 the doctrine is, that we must have died unto "law" in order to union with Christ and fruitfulness unto God, and the Apostle twice asserts that we have died unto law by the body of Christ (vv. 4, 6), so that law has no longer dominion over us, because we have died; and he proves that sin would have dominion over one even quickened by the Spirit, if he were put under law, instead of being delivered by Christ. Deliverance from sin and deliverance from law by the cross of Christ are the introduction into a new life, and the basis of "righteousness and holiness of truth."
Presbutes The Christian Annotator 3:367, 368 (1856).