ISTALLAZIONE. – The i. (a term used alongside inthronisatio for bishops and the Supreme Pontiff) is the taking of possession of a benefice, whether consistorial or non-consistorial, called institutio corporalis (can. 1443 § 2). For consistorial benefices, the CIC prefers the expression « possessionem capere » (cann. 293 § 2, 313, 322 § 1, 334 § 2, 353), while for non-consistorial benefices it uses the term « missio in possessionem » (can. 1443 § 2).
In current law, i. is not merely a complementary rite, but the concluding act of the provision of a benefice, which confers the exercitium iuris in one’s own benefice (cann. 334 § 2, 461, 1446, 1472 etc.).
Under the law of the Decretals, it constituted one of the archdeacon’s functions and subsequently those of the vicars general and forane; now, in itself, it is reserved to the Ordinary, who may not only delegate others but, for a just cause, dispense from the form prescribed by the canons or customs for taking possession, which may also be carried out through a procurator furnished with a special mandate (cann. 1443-45). Through the taking of possession, the appointee not only acquires every spiritual and temporal right pertaining to the benefice (can. 1472), but, ipso iure, the office or benefice incompatible with the new one becomes vacant (can. 2396; V. INCOMPATIBILITÀ). If the taking of possession, even though invalid, continues for three years, it gives the right of prescription over the benefice, provided, naturally, that there has been neither bad faith nor simony (can. 1446).