Believers - Dead to the Law as a Covenant of Works

"Dead to the law. — By the term the law, in this place, is intended that law which is obligatory, both on Jews and Gentiles. It is the law, the work of which is written in the hearts of all men ; and that law which was given to the Jews in which they rested, chap. ii., 17. It is the law, taken in the largest extent of the word, including the whole will of God in any way manifested to all mankind, whether Jew or Gentile. All those whom the Apostle was addressing, had been under this law in their unconverted state...

"Dead to the law means freedom from the power of the law, as having endured its curse and satisfied its demands. It has ceased to have a claim on the obedience of believers in order to life, although it still remains their rule of duty. All men are by nature placed under the law, as the covenant of works made with the first man, who, as the Apostle had been teaching in the fifth chapter, was the federal or covenant-head of all his posterity; and it is only when they are united to Christ that they are freed from this covenant... 

"What is simply a law implies no more than a direction and obligation authoritatively enforcing obedience. A covenant implies promises made on certain conditions, with threatenings added, if such conditions be not fulfilled. The language, accordingly, of the law, as the covenant of works, is, " Do and live;" or, " If thou wilt enter into life, keep the commandments;"' and " cursed is every one that continueth not in all things that are written in the book of the law to do them." It thus requires perfect obedience as the condition of life, and pronounces a curse on the smallest failure. This law is here represented as being man's original or first husband. But it is now a broken law, and there fore all men are by nature under its curse...

"But though believers, in virtue of their marriage with Christ, are no longer under the law in respect to its power to award life or death, they are, as the Apostle says, 1 Cor. ix., 21, "Not without law to God, but under law to Christ." They receive it from his hand as the rule of their duty, and are taught by his grace to love and delight in it ; and being delivered from its curse, they are engaged by the strongest additional motives to yield to it obedience. He hath made it the inviolable law of his kingdom. When Luther discovered the distinction between the law as a covenant and as a rule, it gave such relief to his mind, that he considered himself as at the gate of paradise."

- Robert Haldane's Romans commentary, pp. 283-284