The Law of Christ

Jesus fulfilled and made the Old Covenant obsolete.
Hebrews 8:13 In speaking of a new covenant, he makes the first one obsolete.

2 Cor. 3:7-8 Now if the ministry of death, carved in letters on stone, came with such glory that the Israelites could not gaze at Moses' face because of its glory, which was being brought to an end, 8 will not the ministry of the Spirit have even more glory?
The ministry of death carved in letters on stone is a reference to the Ten Commandments. The Old Covenant was brought to an end and replaced by the ministry of the Spirit. This ministry of the Spirit is revealed in the New Covenant that was promised by Jeremiah [Jer. 31:31-34] and fulfilled as Hebrews 8 describes. The Old Covenant was a ministry of death given to the physical nation of Israel and most of them died in unbelief [Rom. 9:27]. The New Covenant is a ministry of life given to regenerated believers and one hundred percent of them are saved. New Covenant believers are NOT under the Old Covenant or its contract the Ten Commandments [Rom. 6:14, Rom. 7:6, Rom. 8:2, Eph. 2:15 Gal. 5:18]. While believers are not under the Ten Commandments as a unit, we are under the precepts and ethical standards of these commandments as they are expressed in the New Covenant revelation of the New Testament. Jesus raised several of these commandments to a higher standard such as the ones on murder and adultery [Mt. 5:27-28, 31-32]. In pointing to his freedom from Old Covenant law, Paul said the following:
1 Cor. 9:20-21 To the Jews I became as a Jew, in order to win Jews. To those under the law I became as one under the law (though not being myself under the law) that I might win those under the law. 21 To those outside the law I became as one outside the law (not being outside the law of God but under the law of Christ) that I might win those outside the law.
Therefore, Paul stated plainly that he was not under the Old Covenant law, but was under the Law of Christ, which is expressed through New Covenant revelation contained in the New Testament. In explaining that Old Covenant law was not permanent but merely a guardian until the coming of faith Paul said:
Galatians 3:25-26 But now that faith has come, we are no longer under a guardian, 26 for in Christ Jesus you are all sons of God, through faith.
What does this mean to be in Christ Jesus rather than be under the Law as a guardian? I believe Paul said it best in Romans 8:2:
Rom. 8:2 For the law of the Spirit of life has set you free in Christ Jesus from the law of sin and death.
If you are looking to the Ten Commandments to be sanctified, you are looking to the ministry of death and are not free. This is the wrong place to look. Look to Jesus Christ, grace, and the Holy Spirit for your sanctification and the Spirit will lead you in the ways of righteousness that are expressed through Christ and his New Covenant teachings [Mt. 17:5, 28:20, Heb. 1:2].