Even though the lexical and syntactical issues are not complex, a short review will set the stage for further discussion to follow. The phrase occurs 6x in Galatians: (2:16 [3x]; 3:2, 5, 10), each time in the form ἐξ ἔργων νόμου. Important to note for contrast is that in Galatians Paul does not use ἔργον by itself in any way which could imply “works” as a general principle; the other two occurrences in Galatians clearly mean something different. In each anarthrous instance of ἔργων νόμου the head noun precedes the genitive noun, and ἔργον is plural while νόμος is genitive singular. The genitive νόμου is best understood as a possessive genitive, genitive of production, or possibly genitive of source. Despite the lack of the article, both ἔργων and νόμου are definite: The context prior to this use in 2:16 points to “works of the Law” in this instance as specific requirements for Jewish conduct and practice found in the Torah. Paul referenced circumcision relative to Titus in 2:3; the conflict over Peter arose because of food. Thus the nouns are both definite by virtue the collocation being essentially monadic, but also well known. So within Galatians “works of the Law” refers to the well-known requirements of the Torah, such as food regulations and circumcision, which were required of Jews by their covenant with God.
The phrase only occurs elsewhere 3x in Romans (2:15; 3:20, 28). The first occurrence is articular (τὸ ἔργον τοῦ νόμου); the second two are anarthrous (ἐξ ἔργων νόμου and χωρὶς ἔργων νόμου respectively). Arguably the singular ἔργον in Rom 2:15 has a meaning different from the plural ἔργων in the other occurrences, but that is not a major problem for Galatians as such since the singular does not occur in that book. See Dunn, Romans, 100, who correctly argues that “the work of the Law” in this context is a positive, commendable attitude of the heart. ↩
In Gal 5:19 Paul writes of “works of the flesh” (τὰ ἔργα τῆς σαρκός), pointing to recognizable actions which stem from the sinful nature of the flesh. In Gal 6:4 he says, “But each one should examine his own work” (τὸ δὲ ἔργον ἑαυτοῦ δοκιμαζέτω ἕκαστος), an admonition for humble self-examination within the context of supporting those caught in sin. Romans, however, has several passages in which “works” could be considered a general principle, not tied directly to the Law; see Rom 2:6, 7; 3:27; 4:6; 9:12, 32; 11:6. ↩