Paul had said believers are "not under the law, but under grace" (Romans 6:14). Now he shows how that can be true. He begins with a principle his readers would readily grant: law rules over a person only while that person lives. Barnes thinks Paul is probably speaking "more particularly to the Jewish members of the Roman church," who would understand the law well. Gill also takes "them that know the law" as Jewish converts who knew "the law of Moses, as the Jews did." Matthew Henry notes that many Christians at Rome "had been Jews, and so were well acquainted with the law." The question secures agreement on a simple point before Paul applies it.

Paul answers with an example. A married woman "is bound by the law to her husband so long as he liveth," but if he dies, "she is loosed from the law of her husband" (Romans 7:2-3). Then he applies it: "ye also are become dead to the law by the body of Christ; that ye should be married to another, even to him who is raised from the dead, that we should bring forth fruit unto God" (Romans 7:4). The result: "we are delivered from the law," so that we "serve in newness of spirit, and not in the oldness of the letter" (Romans 7:6).

In Greek the question opens with a word that means "are you ignorant" (agnoeite), preceded by "Or." The ESV keeps that "Or" ("Or do you not know").

"Hath dominion" translates kyrieuei, glossed "rules over" in the interlinear. It is the same verb Paul used in Romans 6:14: "sin shall not have dominion over you." Barnes gives the sense of the principle: "death releases a man from the laws by which he was bound in life."

In Paul's teaching, freedom from the law comes through death and new union. Believers have died with Christ, and now they belong "to another, even to him who is raised from the dead" (Romans 7:4). The purpose is not to live without any claim on them, but to "bring forth fruit unto God."

The law itself is not the problem. Paul will soon say "the law is holy, and the commandment holy, and just, and good" (Romans 7:12). What changes is the relationship: from bondage to a law that could not give life, to belonging to a living Lord.