According to Maria Theresa's rescript, Fiume was created a corpus separatum – that is, a political body with greater autonomy than a Free imperial city or a Hungarian county, and a territory comparable to the other partes adnexae constituting the Crown of St Stephen.

The act presented a precedent for the Hungarian constitutional praxis, since it was the first time that a part of the Holy Roman Empire (and a hereditary fief of the Habsburgs) was given to the Hungarian-Croatian kingdom.

The Croatians refused to accept the Hungarian reading of the document - they denied that the City could have been excluded from the surrounding territory, that was already framed into a comitatus.

During the Napoleonic Wars, the city was briefly part of the Illyrian Provinces, ending its status as corpus separatum.

Fiume returned to the Hungarian Crown in 1822; after the Revolution of 1848 and the enactment of the Austrian March Constitution, the city was included in the autonomous Croatian kingdom as a seat of a comitatus with no special autonomy.

The final Croatian–Hungarian Settlement left the possession of Fiume unsettled, pending future negotiations according to article 66, as it appeared in the Croatian version, while in the Hungarian version Fiume was declared a Corpus separatum directly connected to the Lands of the Crown of Saint Stephen and therefore not falling within the domain of Croatian autonomy within the kingdom, but within the domain of the joint Hungarian parliament and government.