Romans 3:20

‘Because by the works of the law will no flesh be justified (accounted as in the right) in his sight, for through the law comes the knowledge of sin.'

And this results from the fact that no flesh can be seen as ‘accounted as in the right' in His sight by keeping ‘the works of the Law', simply because no man can achieve the perfection required. Such a position cannot be achieved by observing the works of the Law (works done in obedience to the Law) for the simple reason that no one can keep them completely (compare Psalms 143:2). What the Law does admirably, and what it has always done, as well as being a guide to living (James 1:22), is to make man aware in his heart of the fact that he has sinned (1 Timothy 1:9). His word is like a fire, and a hammer that breaks the rock in pieces (Jeremiah 23:29). It discerns the thoughts and intents of the heart (Hebrews 4:12). It makes men aware of their guilt.

Of course the Law in itself was never intended originally to be a way by which men could achieve eternal life. In so far as it became that it was the invention of a later age. It was intended rather to turn men to God in repentance and faith, as they looked to Him for His compassion and mercy. The stipulations of the Law represented the stipulations required of them by their Suzerain Lord, as the One Who had by grace redeemed them out of Egypt (Exodus 20:1). Having been redeemed, and having thereby become His, they were to obey His stipulations. Their failures, if accompanied by genuine repentance, would then be dealt with through the sacrificial system. But that did not operate automatically. It required a right attitude of heart (Isaiah 1:11). There was no thought of them earning eternal life by simply observing it.

To be ‘justified' means to be ‘accounted as in the right', whether genuinely so or not. It is a legal term and refers to a judicial verdict passed on men which declares them to be totally vindicated (dikaio-o only ever has that meaning). The court declares them free from all charges. They are seen as ‘in the right' in the eyes of the law. It says nothing about what they actually are in themselves. (Thus the wicked can be ‘justified' for a reward - Isaiah 5:23 LXX; Proverbs 17:15 LXX).