OCCUPATION. – This is one of the original modes of acquiring ownership, indeed the first of them both historically and in importance at the origins of society. It consists in taking possession of a thing that has no owner (res nullius), with the intention of retaining it as one’s own (animus occupandi). In the technical juridical sense, this kind of o. is the reduction of a res nullius to one’s own de facto power for the purpose of making it one’s own in law, with the consequent acquisition of ownership. Such an act is truly capable of concretely determining the right of ownership. Through o., in fact, no right of another is violated, since the things in question have no owner. Moreover, it inherently includes the animus of possessing the thing for oneself. For this reason, always and among all peoples, o. has been regarded as a sufficient title for acquiring ownership of res nullius.
The ethical foundation of o. therefore lies in the principle of natural law according to which a thing belonging to no one, or one that has been abandoned (vacua possessionis), belongs to the first occupant.
For moral theologians, in order for o. to be a legitimate title to the acquisition of ownership, the following conditions must be present: 1) there must be a suitable object, that is, one morally and physically capable of being apprehended and exclusively possessed, and there must not already be another title of ownership over it (otherwise theft would be committed), and it must be in commercio, that is, capable of entering into patrimonial legal relations; 2) there must be a material and effective taking of possession; this, however, may be physical or moral according to the nature of the thing or according to the provisions of positive legal systems. This apprehension must therefore consist in the thing’s effective availability; 3) there must be the intention (animus) of making the thing one’s own; without this intention, the object would remain in the person’s hands just as it would in any other place, liable to be taken anew by anyone.