The Law of God presupposes Freewill.

For the Giver of Freewill is not so confused (in mind) as this man who is divided (against himself) part against part, that He should become involved in a struggle with His nature. For He gave us Freewill which, by His permission, receives good and evil impulses, and He furthermore ordained a Law for it that it should not do overtly those Evils which by His permission stir invisibly in it. And let us inquire a little. Either though He may have had the means to give us Freewill, He did not wish to give it, though He may have been able to give it, or He may [xix] not have had the means to give, and on this account He was unable to give it. And how was He Who was unable to give freewill able to give a Law when there was no Freewill ? But if He gave the Law, the righteousness which is in His Law reproves our Freewill, for He rewards it according to its works.