There are two points concerning the law, one being our relationship to the law and the second is the relationship of the law to sinners saved by grace. Which point is Paul making when he says...'Do we then make void the law through faith? God forbid: yea, we establish the law.
The laws relationship to us is not made void by our faith because the law does not change. If I covet, I have sinned and offended Christ and the Holy Spirit. Our faith in the righteousness of Christ, that justifies us, does not change the law but it is not the law that justifies us when we were sinners or when we sin. Rather, the sinner is justified by grace through faith in the blood of Christ. Our faith in the righteousness of Christ establishes and fulfills the law (which includes the 10 commandments) for the purpose of which the law was given, because of transgressions and to make sin exceedingly sinful, so that the whole world would be guilty and every mouth might be stopped of boasting of their own righteousness.
However, the law has been made void for the purpose of establishing righteousness through its deeds and made inoperative because Christ was judged, delivered up for our offenses and bore our sin being crucified on the cross. He put and took away all sin (including iniquity, transgressions and all trespasses), offering his own righteousness to the Father on our behalf and has also given the Holy Spirit unto those who believe in his blood sacrifice for the remission of sin. So our relationship to the law has changed and we are no longer under the law for righteousness but under grace, making the law inoperative and ineffective because we now have the Spirit of truth that has set us free making us new creatures in Christ and who convicts the world of sin, of righteousness and of judgment.
When we walk and are led by the Spirit through faith we are not under the law (the whole law Gal 5:18) and we live by the grace and the glory of the ministration of the Spirit that has exceeded and excelled the law, making it obsolete and causing it vanish and to be done away (2 Cor 3:5-10). The reference made to the law is the whole law which includes the law of the (10) commandments. You can't separate the law of the (10) commandments from the whole law, James did not do that (James 2:10), so by what authority do some of you? Even Jesus said that the scriptures can not be broken (John 10:35). We do not do away with or break up the scriptures by not being under the law, but we establish the law by being under grace without the deeds of the law. Our faith in the finished work of Christ and in his righteousness establishes the law because our faith works by love which fulfills the law. If we walk in the Spirit and are led by the Spirit we are filled with the love of God and thereby fulfill the law (Gal 5:13-26). Got to think about that one!