Rom. 3:20 Therefore by the deeds of the law there shall no flesh be justified in his sight: for by the law is the knowledge of sin. The Law of Moses is designed to provide "the knowledge of sin." It does this by distinguishing between [and thus defining] what is right in God's sight versus what is wrong in God's sight. The "deeds of the law" or "works of the law" are responses of the Jews in keeping with what the Law defines as good and right. This should be obvious as those attitudes/actions the law defined as sin would never be used by a Jew for justification before God and that is the subject in the above verse - "justified in His sight." The Mosaic Law was founded upon the Ten Commandments as its basic foundation. The Civil law was nothing more than application of the ten commandments to their Judicial system. The Ceremonial law was nothing more than application of the ten commandments to their religious system. The ceremonial law gave a visual representation of righteousness and sin (clean versus unclean) in everything the Jew did in his social and religious life. Hence, the law of Moses was the most comprehensive application of moral right and wrong to every facit of the Jewish life more than any other people upon the face of the earth. Therefore, if doing the good works of the most comprehensive revealed standard of righteousness on planet earth was insufficient to acheive "justification" before God then no lessor application of good works could achieve that goal. Hence, Paul argues from greater to lessor. For example, the Gentile had a lessor standard of righteousness revealed through conscience (Rom. 2:14-15) for which they would be held accountable for their attitudes and actions. However, in judgement it would be the "jew first" and then the Gentile as the Jew had far more revealed light of right and wrong. Thus, "deeds of the law" represents the most refined and comprehensive attempts by any human being to find justification before God based upon their attempted conformation to the most comprehensive standard of righteousness ever given to man. Hence, it simply means "good works." This is seen clearly by Paul providing the Pre-Mosaic Law Abraham and his "works" as the role model in regard to being insufficient for justification before God: Rom. 4:1 ¶ What shall we say then that Abraham our father, as pertaining to the flesh, hath found? 2 For if Abraham were justified by works, he hath whereof to glory; but not before God. Obviously, Abraham would not attempt to be justified "before God" by evil works and therefore what is in view is the possibility of Abraham being justified before God by what could be regarded in man's sight as good works. Hence, Romans 3:20 and Romans 4:1-2 forbid justification before God by either "deeds" or "works" that are attempts to conform to the Law of Moses or attempts to conform to the law of conscience. Human responses to conform to the Law of God written upon stone or conscience cannot justify anyone before God simply because such responses "come short of the glory of God" (Rom. 3:23) which speaks directly to the root of all sin in man which is his MOTIVE for all that he thinks, says and does for some other motive than "the glory of God." Hence, he is incapable of either being or doing good as that requires a righteous heart that seeks the glory of God in all that he does: 9 What then? are we better than they? No, in no wise: for we have before proved both Jews and Gentiles, that they are all under sin; 10 As it is written, There is none righteous, no, not one: 11 There is none that understandeth, there is none that seeketh after God. 12 They are all gone out of the way, they are together become unprofitable; there is none that doeth good, no, not one. 13 Their throat is an open sepulchre; with their tongues they have used deceit; the poison of asps is under their lips: 14 Whose mouth is full of cursing and bitterness: 15 Their feet are swift to shed blood: 16 Destruction and misery are in their ways: 17 And the way of peace have they not known: 18 There is no fear of God before their eyes. 19 ¶ Now we know that what things soever the law saith, it saith to them who are under the law: that every mouth may be stopped, and all the world may become guilty before God. 20 Therefore by the deeds of the law there shall no flesh be justified in his sight: for by the law is the knowledge of sin. To be "UNDER sin" (v. 9) is to be "UNDER law" (v. 19) and that is equally true of all Gentiles as Jews (v. 9) whether that Law be in its most comprehensive form (Moses) or in its least comprehensive form (conscience) it is still the SAME LAW originating from the SAME GOD who has the SAME BASIC STANDARD OF RIGHTEOUSNESS: Rom. 2:14 For when the Gentiles, which have not the law, do by nature the things contained in the law, these, having not the law, are a law unto themselves: 15 Which shew the work of the law written in their hearts, their conscience also bearing witness, and their thoughts the mean while accusing or else excusing one another CONCLUSION: If "good" works as defined by the most comprehensive revelation of God's law (Moses) will not justify a person before God; then "good" works by the least comphrensive revelation of God's law (conscience) will not justify a person "before God." Hence, the only way for both to be justified before God is ANOTHER WAY provided by God in and through ANOTHER PERSON and His good works- Rom. 3:24-26.