"Paul does not depict the Christian as one who is under obligation to the specific stipulations of the Mosaic law. The Christian is no longer 'under the [Mosaic] law' . . . . but under 'the law of Christ." (170)
"As in John 1:17, then, 'law' and 'grace' [in Rom 6.14] contrast the old age of bondage and 'tutelage' (cf. Gal. 3:25) with the new age of freedom and 'sonship' (cf. Gal. 4:1-7; Rom 8:14-17)." (389)
"To be 'under law' is to be subject to the constraining and sin-strengthening regime of the old age; to be 'under grace' is to be subject to the new age in which freedom from the power of sin is available." (389)
--from his Romans (NICNT).