Once the set of prescriptions binding an autonomous free will is established, rational agents hold themselves to that same set of prescriptions in practical matters.

Kant says that a will that cannot exercise itself except under the Idea of its freedom is free from a practical point of view (im practischer Absicht). In saying such wills are free from a practical point of view, he is saying that in engaging in practical endeavors — trying to decide what to do, what to hold oneself and others responsible for, and so on — one is justified in holding oneself to all of the principles to which one would be justified in holding wills that are autonomous free wills.