Law and grace
'Not under law but under grace' beside 'not one jot or tittle will pass from the law' — law, gospel and the Christian's obligation (with Romans 3:31; 7:12; the Jerusalem council of Acts 15).
Romans 6:14-15
14For sin will not have dominion over you. For you are not under law, but under grace.
15What then? Shall we sin, because we are not under law, but under grace? May it never be!
Matthew 5:17-19
17“Don’t think that I came to destroy the law or the prophets. I didn’t come to destroy, but to fulfill.
18For most certainly, I tell you, until heaven and earth pass away, not even one smallest letter or one tiny pen stroke shall in any way pass away from the law, until all things are accomplished.
19Whoever, therefore, shall break one of these least commandments, and teach others to do so, shall be called least in the Kingdom of Heaven; but whoever shall do and teach them shall be called great in the Kingdom of Heaven.
What each tradition says
Rabbinic / Midrashic
Ginzberg and Kohler state that Paul set up a theory that the Law was completely abrogated after Jesus. This directly opposed Jewish and Judaeo-Christian thought, which held that the Law was the only means by which man could be justified before God; the Mak. Mishnah says God gave Israel many laws and commandments to justify it.
Louis Ginzberg (1873-1953) and Kaufmann Kohler (1843-1926), The Jewish Encyclopedia, vol. 1, s.v. 'Antinomianism' (New York: Funk & Wagnalls, 1901-1906) — article, opening section (before the subheading 'Paulinism and Pharisaism')
Patristic
Augustine says the law was given so that grace might be sought, and grace was given so that the law might be fulfilled. The law was not at fault when it was not fulfilled; the carnal mind was. The law demonstrates that fault, and grace heals it.
Augustine of Hippo (354-430), On the Spirit and the Letter (trans. Peter Holmes and Robert Ernest Wallis; rev. Benjamin B. Warfield), in Nicene and Post-Nicene Fathers, ser. 1, vol. 5 (ed. Philip Schaff; Buffalo: Christian Literature Publishing Co., 1887) — ch. 34 ('The Law; Grace'), on Jeremiah 31:31-34 and Galatians 3:23-24
Catholic
Aquinas states that the Law could not accomplish this, but foreshadowed it by certain ceremonial actions and promised it in words. In this respect, the New Law fulfils the Old by justifying men through the power of Christ's Passion.
Thomas Aquinas (1225-1274); trans. Fathers of the English Dominican Province (1920), Summa Theologiae, Second and Revised Edition (New Advent) — I-II, q. 107, a. 2 ('Whether the New Law fulfils the Old?'), reply
Orthodox
Chrysostom says the law labored to make man righteous but had no power to do so. Christ came and brought the way of righteousness by faith, establishing what the law desired: what the law could not accomplish by letters, He accomplished by faith, so He did not destroy the law.
John Chrysostom (c. 349-407), Homilies on the Gospel of St. Matthew (trans. George Prevost, rev. M. B. Riddle), in Nicene and Post-Nicene Fathers, ser. 1, vol. 10 (ed. Philip Schaff; New York: Christian Literature Publishing Co., 1888) — Homily XVI, section 3 (on Matthew 5:17)
Reformed / Protestant
The Westminster Confession states that the previously mentioned uses of the law are not contrary to the grace of the gospel. Rather, they sweetly comply with it.
The Westminster Assembly (1643-1653), The Westminster Confession of Faith (1646), in Philip Schaff, The Creeds of Christendom, vol. 3 (New York: Harper & Brothers, 1877) — ch. XIX ('Of the Law of God'), §VII
Evangelical
Wesley explains "not under law" as not under a dispensation of terror and bondage that only shows sin without enabling you to conquer it. "Under grace" means the merciful gospel dispensation, which brings complete victory over sin to everyone under the powerful influences of the Spirit of Christ.
John Wesley (1703-1791), Explanatory Notes upon the New Testament (1755; CCEL's 'Wesley's Notes on the Bible') — Note on Romans 6:14