INTERIM. – A Latin term indicating the interval of time between one event and another, and which, used specifically in the terminology of public law, refers to the exercise of a function on a provisional basis, during the period in which the office is vacant.
The institution of the i. occurs most often in relation to organs of government, where, in the event of a minister’s absence, incapacity, or resignation, provision may be made by appointing as i. a minister who holds another portfolio. The institution also applies to diplomatic offices, including those of the Holy See, where the temporary head of a diplomatic mission is called an incaricato d'affari ad i. The powers deriving from an appointment ad i., although theoretically the same as those deriving from definitive investiture, are normally exercised, in keeping with the provisional nature of the appointment, with regard to urgent acts and ordinary administration.
In history, the name of i. is associated with the collection of thirty theological propositions that Carlo V had promulgated, with the approval of the Roman Curia, at Augsburg on 15 May 1548, in order to calm the religious disturbances that had arisen in Germany after the transfer of the Council of Trent to Bologna. The name of the collection alluded to its provisional character, since it was to remain in force until the Council’s definitive decisions.