Vincent's NT Word Studies
21. Now (nuni) Logical, not temporal. In this state of the case. Expressing the contrast between two relations - dependence on the law and non-dependence on the law.Without the law. In a sphere different from that in which the law says "Do this and live."
Is manifested (pefanerwtai). Rev., hath been manifested, rendering the perfect tense more strictly. Hath been manifested and now lies open to view. See on John xxi. 1, and on revelation, Apoc. i. 1 The word implies a previous hiding. See Mark iv. 22; Col. i. 26, 27.
Being witnessed (marturoumenh). Borne witness to; attested. The present participle indicates that this testimony is now being borne by the Old Testament to the new dispensation.
Robertson's NT Word Studies
3:21 {But now apart from the law} (nuni de cwris nomou). He now (nuni emphatic logical transition) proceeds carefully in verses #21-31 the {nature} of the God-kind of righteousness which stands manifested (dikaiosune qeou pephaner"tai, perfect passive indicative of fanerow, to make manifest), the {necessity} of which he has shown in #1:18-3:20. this God kind of righteousness is "apart from law" of any kind and all of grace (cariti) as he will show in verse #24. But it is not a new discovery on the part of Paul, but "witnessed by the law and the prophets" (marturoumen, present passive participle, hupo tou nomou kai t"n propht"n), made plain continuously by God himself.