Romans 7:1-14
Paul gives a very good explanation for the purpose of the law. God never expected that men and women would be obedient to the law. He told Adam and Eve not the eat of the fruit of only one tree. They were free to eat of all the other pleasures in the garden, but this one tree was special and reserved. They knew it was forbidden, but they ate anyway. With disobedience came death.
Until the Children of Israel were ready to leave Egypt, death was the consequence of their lives. Some found grace and blessing through obedience, but there was no general law until Moses received the Commandments. The Commandments never made people righteous. They only showed us what sin was. In the Passover, God showed them the blood of the lamb smeared on the doorpost as a symbol of the sacrifice for their sin. They ate the dinner inside the house and the Angel of Death passed over the places where the blood was.
Now Paul says that the Law is good and spiritual and righteous, but in us it is intended to show where the sin resides. The stark perfection of the law reveals the sinful attitude and broken promise of a human life. The Blood of the Lamb obscures the sin and covers the black mark with his sacrificial purity.
It is not that the law is no longer effective, but that we have died to the law by being made alive to Jesus Christ. This is a difficult concept to understand. We don't feel dead to the Law: We feel condemned by it. If we could move on to the point that we feel our sins condemned by Jesus, rather than the law, we may be able to understand the forgiving and cleansing that comes through his blood.
When we feel condemned by the Law there is no recourse. The Law says: The soul that sins shall die. Jesus says: The soul that sins shall be forgiven. Of course he called us to die to sin and to the Law; then we are raised to resurrection life by his forgiveness, by his blood.