a collection of church documents (decrees and epistles of popes, resolutions of ecumenical councils, etc.), mainly counterfeited, which appeared in the middle of the ninth century in the Carolingian Empire to justify the theocratic claims of the popes.
The compiler of the Pseudo-Isidorian Decretals hid under the pen name of Isidore Mercator. In the theological literature the compilation of the Pseudo-Isidorian Decretals was ascribed to Bishop Isidore of Seville (sixth to seventh centuries). The documents included in the collection maintained the supreme authority of the pope in the universal church and his independence from secular authorities and supported the idea of the infallibility of the pope. The Pseudo-Isidorian Decretals were cited as a basis for canonical law and were widely used by the papacy in the struggle for supremacy over the Western European secular sovereigns. The falseness of the Pseudo-Isidorian Decretals was proved by Protestant scientists (the Magdeburg centuriators) as early as the 16th century and was irrefutably established in the 17th century.