Romans 9:31

The law of righteousness. Literally, “a law of righteousness,” meaning, a law producing righteousness. What the Gentiles are described as not seeking, yet obtaining, is “righteousness.” But what the Jews are described as following after, yet not attaining, is “a law of righteousness.” This phrase has been variously interpreted. Some regard it as a specific reference to the law of the OT. Others understand the phrase to mean that the Jews were seeking for a principle and rule of moral and religious life that would make them righteous (compare the use of the word “law” in the expression “the law of faith”; see on chapter 3:27; cf. chapter 7:23). This principle the Jews thought they had found in their system of moral and religious laws. But since they were never able to live up to the requirements of those laws, their principle of righteousness could not produce the righteousness for which they sought. This drove them to still further multiplication of religious laws in their legalistic quest for a principle of life that would make them righteous in the sight of God.

Another interpretation, and one well suited to the context, is to regard the phrase “a law of righteousness” as the equivalent of “the righteousness which is based on law.” Paul’s emphasis in these verses is upon the legalistic nature of Israel’s pursuit of righteousness.

To the law. Literally, “to a law.” Textual evidence favors (cf. p. 10) the omission of the word “righteousness” in this second phrase. Israel followed after “a law of righteousness” but did not succeed in arriving at that law. The reason for this failure is that righteousness based on law demands the perfect fulfillment of that law, and this obedience men in their own strength are not able to give. Consequently, in depending for righteousness upon a law which, in their own strength, they could not obey, the Jews failed to arrive either at the ideals prescribed by the law or at the righteousness they were pursuing.