"weak[ness]" in Rom. 8.3

I'm working my way through Romans 8, and perhaps it occasions no surprise to find that this passage is kicking my butt. For example, my reaction to v. 3: "Focus, Paul. Focus." Complete sentences are not only useful for effective communication but also for theological clarity. But Paul seems to have had other ideas.

But I could use your help (especially you Pauline and Romans specialists out there). Romans 8.3 begins with the incomplete phrase, "For the impossibility of the Torah in that which it was weak through the flesh . . . " [Τὸ γὰρ ἀδύνατον τοῦ νόμου ἐν ᾧ ἠσθένει διὰ τῆς σαρκός; to gar adynaton tou nomou en hō ēsthenei dia tēs sarkos]. Clearly I'm making certain interpretive decisions already (e.g., nomos = Torah). But I'm struggling to determine the subject of the imperfect verb ēsthenei The obvious option, grammatically, is nomos, and every translation and commentator I've consulted takes this option.

But here's the problem. Everywhere in Romans, when Paul uses the language of "weakness," the what that he describes as weak is a person. And with the exception of 4.19, where Abraham did not grow weak [μὴ ἀσθενήσας; mē asthenēsas] in his faith, Paul is always referring to his readers (sometimes including himself [5.6; 8.26], sometimes differentiating some of his readers from others [14.1; 15.1]). A wider search reveals a similar pattern; nowhere in forty-four uses of ἀσθενέω, ἀσθενής, ἀσθένεια, or ἀσθένημα does Paul describe Torah (or nomos on any other interpretation) as "weak." While it's certainly possible that, this one time here at Rom. 8.3, Paul describes the nomos as "weakened by the flesh, I am surprised at the lack of discussion of this unusual usage.

Robert Jewett illustrates the problem, but I don't think he provides any real help in solving it. He rightly notes that the verb ēsthenei is "an expression ordinarily referring to someone becoming ill" (Romans, 483). He also, again rightly, notes that Paul's usage here, if it refers to the nomos, would be "unique to the NT." But then he says, inexplicably I think, that this unique phrase "recapitulates the argument of the preceding chapter about human arrogance and the quest for honor, which corrupt the law and destroy its capacity to achieve the good." The problem here, however, is that Paul never in Romans 7 described the nomos as weak or corrupted or powerless; the image in Rom. 7.7–25 was of Paul's persona—the role from within which he speaks ("speech-in-character")—as helpless and impotent to stop sin from acting within/among his members. Paul's persona, and not nomos, was weak in Romans 7. So how 8.3 "recapitulates" the argument of Romans 7, as Jewett suggests, is unclear to me.

So I'd like to ask the following questions:

• Are there contextual reasons that make us confident that Paul must be describing the nomos here as weakened (notice that I'm not asking whether nomos = Torah, though that might be a factor that affects the question I am asking)?
• Are there other ways to understand the relative clause en hō ēsthenei, so that we interpret ἀσθενεῖν in 8.3 in such a way that fits with every other use of this word in the Pauline corpus?
• Are there discussions in the secondary literature that note and address this complex of issues?
• If Paul is saying that the nomos was weakened through the flesh, what does he mean?

Any thoughts?