The literature on possessio has now assumed such proportions that it will require a volume at least to do anything like justice to it. The purpose of this article is only to outline an approach to the Roman law of possessio as suggested by Kocourek's analysis of possession in the common law. The present writer believes that a substantial similarity exists between these two great systems in their approach to possession and this has not been due to any borrowing by the one from the other: a fact which, if proved, should be of no little jurisprudential interest. It is, therefore, merely as a prologue to a fuller exposition elsewhere that the following contentions are advanced as to possessio in Roman law.
Kocourek, writing of the common law, maintained that “possession” as a juridical concept distinct from physical control on the one hand and the right to have physical control on the other was unnecessary. If a person actually holds a thing, he either has a right to continue holding it or he has no right; if he is not holding a thing, he either has or has not a right to hold it. In all cases what matters is the right to have physical control. As long as the term “possession” is confined to physical control, no harm is done, but what Kocourek objects to is that mysterious tertium quid, called “possession,” from which are distinguished both physical control and the right to it, the former being known variously as “de facto possession,” “custody,” “detention,” and the latter as the “right to possess.”