IIUM was once a private university. As the University's language of instruction was not to be Malay but instead English and Arabic, which was initially prohibited by Malaysian law, IIUM was initially incorporated under the currently-repealed Companies Act 1965. However, IIUM was officially made a public university on 23 May 1983, in accordance with Section 5A (2) of the Universities and University Colleges Act 1971, when the University received its Establishment Order from the then King, Sultan Ahmad Shah of Pahang, after an exchange of Diplomatic Notes of Co-sponsorship between the Government of Malaysia, seven other governments and OIC.