"The law always works wrath. Now this is a most important statement. He says that what the Law does is to produce wrath; and wrath is the very opposite of the promise of blessing. Wrath means punishment. The promise offers an inheritance and life and joy and glory. Wrath means punishment and suffering ... how does the law work wrath? Law always leads, as he has shown so abundantly to condemnation; and it does that because of our sinfulness. What the Law does is to show us of our weakness and sins.
That was the effect of the giving of the Law. God never gave the law that mean might be saved by it. The business of the Law was to bring out the character of sin that it might show the "exceeding sinfulness of sin" ... The law pin-points sin and therefore aggravates it and thereby works wrath".
Dr Martyn Lloyd-Jones - "Romans 3:20 - 4:25: Atonement and Justification" - Banner of Truth Trust, Edinburgh (1971) - (p194).