In the present-day debate on free will, Kant's theory of freedom has been dismissed as bad metaphysics. This however leaves decisive questions partially unanswered, namely 1. To what concept of freedom does Kant lay claim? 2. What functions are ascribed to it? 3. What proof does Kant advance to justify it? The author demonstrates that Kant's theory has not been adequately represented in all three points, and resumes the negotiation about its systematic validity.