Note 1 at Gal. 3:19: Paul had already proven that the law was not given to bring justification (see notes 3-4 at Rom. 3:19, p. 757; see note 14 at Rom. 3:31, p. 760). Then why was it given? It was added (Gal. 3:19) to the covenant of promise (Gal. 3:18) to magnify our sin (see note 5 at Rom. 7:11, p. 788), and therefore remove any false ideas we might have of saving ourselves. It ruled out the possibility of self salvation and made us ready for the covenant of grace (Gal. 3:24). It was to remain valid and in force until the coming of the one true descendant of Abraham, i.e. Christ (Gal. 3:16).

Note 2 at Gal. 3:19: The use of the words "added" and "till" are very significant. The law was not God's first nor His primary way of dealing with mankind. The covenant of grace or promise (Gal. 3:18) had already been in effect for 430 years before God gave the law through Moses (Gal. 3:17; see note 2 at Rom. 4:10, p. 764) and therefore had greater authority.

This verse also uses the word "till" showing that the law was only temporary until Christ came. When Christ came, He put an end to the law for righteousness (Rom. 10:4). Anyone who advocates the keeping of the law for the purpose of right standing with God is going back to an Old Testament system of law that has been abolished (2 Cor. 3:13; Eph. 2:15) and is making the work of Christ void in his life (Gal. 2:21).

Note 3 at Gal. 3:19: The word "mediator" literally means "to be in the middle or midst." It is "one who mediates between two parties with a view to producing peace" (W.E. Vine). Moses was the mediator God used to make the Old Testament covenant of law between Himself and the Jews. In the New Testament, Jesus is the mediator between God and man (1 Tim. 2:5; see note 4 at v. 20).