DE FACTO and DE JURE.—With some offences the penalty attaches to the offender at the instant when the fact is committed; in others, not until he is convicted by law. In the former case he is guilty de facto, in the latter de jure.
De facto is commonly used in the sense of actually or really, and de jure in the sense of rightfully or legally; hence the philosophical use of the terms. A de facto proof is a mere «natural history» of the facts; a de jure proof is a vindication of their existence; e.g., the principle of causality may be proved de facto, i.e., it may be shown to be as a matter of fact accepted and acted upon by men; or de jure, i.e., it may be shown to be the necessary presupposition of the facts of experience, or of experience itself. This last is the Kantian method of proof, called by him Transcendental Deduction.