In passages like Deut 28:58 (cf. 29:29 [Heb 29:28]; 31:12; 32:46), Josh 1:7 (cf. 22:5; 23:6) and Neh 9:34 (cf. 2 Chr 14:3; 33:8), "do/perform the law" has reference to the entire law, not to one particular ordinance. These same passages call for the implementation of covenant curses for disobedience to the law. By context these texts do not refer to ethnic or social markers identifying Israel. Instead, they refer to the entire Mosaic legislation including every facet of that law. The point is that such references to works of the law are virtually identical with Paul's use of "works of the law” in both Galatians and Romans.
In the intertestamental period, sectarian authors at Qumran spoke of the members of their community as "doers/workers of the law" (ośê hattorāh, 1QpHab 7:11; 8:1; 12:4). They did not indicate that "the law” in such cases was limited to circumcision, Sabbath-keeping, or dietary regulations. Joseph A. Fitzmyer, one of the world's leading authorities on Qumran, Aramaic, and the intertestamental period, concludes that Qumran materials (especially 4QMMT 3.29) rule out the suggestion of both Dunn, about a restricted sense of erga nomou, ..., and Gaston, that the gen. nomou is a subjective gen[itive]."' Fitzmyer goes on to declare that
The Qumran usage makes it clear that "deeds of the law” refers, indeed, to things prescribed or required by the Mosaic law. To the extent that a "works righteousness" would be indicated by the phrase in question, this reading reveals that Paul knew whereof he was speaking when he took issue with contemporary Judaism and its attitude to legal regulations. In 4QMMT the phrase is used precisely in a context mentioning sdgh, "uprightness," and employs the very words of Gen 15:6 that Paul quotes about Abraham in 4:2c.
He is clearly at odds with the NPP’s limitation of the works to circumcision, Sabbath-keeping, and dietary regulations in a context dealing with righteousness or justification.
William D. Barrick, The New Perspective and "Works of the Law" (Gal. 2:16 and Rom. 3:20), p. 278-279