VII. To question (wont to be agitated here) whether Christ is and can be called a legislator. We answer in a few words that Christ can be viewed in two ways: either absolutely and theologically (inasmuch as he is the Word [Logos] the same God with the Father and the Holy Spirit); or relatively and economically (inasmuch as he is the God-man [Theanthropos] and the Mediator between God and men). In the former respect, he is the one legislator who can save and destroy (James 4:12). In the latter, he is neither properly a legislator as Moses was (because he is opposed to Moses and his law as the author of grace and truth, John 1:17); nor principally only because his principal office was to reveal to us a mystery of the gospel. Still nothing hinders our calling him a legislator and less principally, both because he was the restorer and vindicator of the law and because he is King and head of his church. Now it belongs to Kings to make laws. Hence he is called a “lawgiver” (mchqq, Isa 33:22) and the doctrine of Christ has also its own law, which prescribes to us faith and obedience in this life. In this sense the law is subordinated to the gospel and the gospel itself is called the law of faith, the royal law of liberty, the law of the Spirit and of life. Still our divines rightly deny (against Romanists and Socinians) that Christ is a lawgiver, inasmuch as a legislator or denotes him who introduces new laws and precepts not contained in the law itself (nor having their foundation in it).
— Francis Turretin, Institutes, 14.8.7