The formation and nature of the Crown of Aragon has always raised problems and lively historiographical debates. One of the most controversial points lies in the nature of the "composite monarchy" (according to the now universally-used terminology of Professor John Elliott) of the Crown of Aragon. Specialists have written a great deal on this topic. Currently, the most common opinion is that it consisted of a dynastic union of heterogeneous kingdoms and principalities (Catalonia, Aragon, Valencia, Mallorca, Sardinia, Sicily, Naples, Roussillon, Cerdanya and others), associated with each other due to their shared sovereign from the same dynasty. This alone, however, does not explain why the Crown of Aragon remained intact for so many centuries. There are deeper reasons. One of them is strictly legal, and we are on the eve of commemorating its centuries-old anniversary.
On December 14, 1319, during the Parliament of Tarragona, King James II (the Just) of Aragon enacted a statute, or law, that maintained unusual importance for centuries to come. In order to justify his motivation, in his preamble, the king and his jurists turned to the authority of the Gospel, in which Jesus prophesied that "every kingdom divided against itself will be laid waste" (Matthew 12: 25, Luke 11: 17). Therefore, stated James II, all kingdoms must remain united and undivided, so that the united strength of many may be more capable of defending justice, without which countries perish; and so that, with the strength of all, inhabitants can better defend themselves from their enemies and public affairs can be preserved. The monarch pointed out that his parents had already tried to separate the kingdoms of Aragon and Valencia and the county of Barcelona in the past and had caused great damage; for the profit and benefit of his subjects, James II therefore ordered that the kingdoms of Aragon and Valencia and the county of Barcelona – along with their claims in the kingdom of Mallorca and in the counties of Roussillon, Cerdanya and other territories – remain henceforth perpetually united and under the same domain, without being separated for any reason nor according to any justification. Among other measures, at the beginning of his reign he also obliged his successors to swear to respect this statute, and declared null and void any position that might be taken against it. Finally, in order to eternally preserve the memory of this law, the king ordered that four copies be dispatched: one to be kept in the Royal Archive (currently the Archives of the Crown of Aragon), and the other three to be preserved in the municipal councils of the cities of Zaragoza, Valencia and Barcelona, as heads of the Kingdom of Aragon, Kingdom of Valencia and Principality of Catalonia, respectively.
James II's law was adopted after the ordeal that followed the death of James I the Conqueror, who, in his testament, divided the kingdoms between his children – something that once again took place when Peter the Great, father of James II, died –. Indeed, during the final months of 1319, a political crisis of the first order was under way, due to the Infante James's – James II's first-born – sudden renunciation of the crown. With James II's statute, strict limitations were introduced on the will of the sovereigns to do as they wished with their kingdoms, making it subject to an irrevocable legal standard. The statue's importance derived from the fact that it legally transformed a merely personal aggregation of kingdoms and principalities into a substantial political entity. Although not everything is not due to this law or statute, its approval strongly contributed to the subsequent legal consistency that the Crown of Aragon had previously lacked.
Although strictly speaking it was a statute or edict, it was known as the "privilege of the union of kingdoms" or the "non-separation of kingdoms." During the medieval period it was granted significant importance. A few months after its promulgation at the end of 1319, the Parliament of Zaragoza of 1320 were convened by King James II so that the prelates, rich men, knights, nobles, and procurators of the kingdom's cities and towns would swear by his son the Infante Don Alfonso as his successor and heir to the crown after Infante James's renunciation; in turn, the Infante Alfonso also swore that he would respect this privilege. Alfonso the Kind confirmed his oath, once he was already a monarch, in 1329, at the behest of the Parliament of Valencia. From then on, and until the reign of Ferdinand II (the Catholic), this oath was confirmed at the beginning of every reign by each king of Aragon. The procedure took place before the Cortes and at the behest of the parliaments. It retained its legal force even in modern times. It was therefore included in the collection of documents, which were called "Liber patrimonii regii", drawn up by the order of Philip II between 1582 and 1590, and known as the Mulasses (referring to a very large mule in local folklore) due to their imposing size. These documents were written in the Archives at the end of the of the sixteenth century. Also included in them are all the confirmations made by the sovereigns up to Alfonso the Magnanimous. In 1627, the deputies of Catalonia wielded against the request presented by the city of Perpignan, on behalf of itself and the Roussillon and Cerdanya counties, to "make a Kingdom and Province of itself" and thus exempt themselves from the jurisdiction of the viceroy and Royal Council of the Principality of Catalonia, as well as from paying taxes to the to the General Deputation of the Principality (Memorial o discurso hecho por el Principado de Cathalvña en respvesta de otro hecho por la villa de Perpiñan en su nombre, y de los Condados de Rossellon y Cerdaña, sobre la desunion y separacion de los dichos condados, que se pide à su Magestad, [Brief or discourse made by the Principality of Catalonia in response to the request of Perpignan, Roussillon and Cerdanya], 1627).
Because of its importance, many historians have seen this brief as the legal basis of the union of Aragon, Valencia and Catalonia. Among the first was the archivist Pere Miquel Carbonell, when he pointed to it – along with the nuptial agreement between Petronila and Ramon Berenguer IV – as the founding document of the Crown (Chroniques de Espanya [Chronicles of Spain], Barcelona, 1546, folio 45v.). The document was included in the Valencian legislative compilation entitled Aureum opus regalium privilegiorum civitatis et regni Valentie, Valencia, 1515, folios 63r-64r. Jerónimo Zurita also acknowledged its immense importance (in Indices rerum ab Aragoniae regibus gestarum an initiis regni ad annum MCDX, Zaragoza, 1578, p. 234; translated into Spanish as Gestas de los Reyes de Aragón [in English, Deeds of the kings of Aragon], ed. A. Canellas López, Zaragoza, 1984, vol. 2, p. 47; and in the Annals of the Crown of Aragon, book. VI, chapter XXXVI, ed. A. Canellas López, Zaragoza, 1978, vol. 3, p. 133). Or, to mention another much later example, José Morales Santisteban used it in his work, Consideraciones sobre la organización política y social de España en los diferentes períodos de su historia [Thoughts on the political and social organization of Spain throughout its different historical periods] (published by Eugenio de Ochoa in Apuntes para una biblioteca de escritores españoles contemporaneous [Notes for a library of contemporaneous Spanish writers], Volume. II, Paris, 1840, p. 551).
The main original document was situated in a register of the Gratiarum series of James II (currently, with the reference ACA,CHANCELLERY,Registers, No. 217, folios. 224r-225r) and another miscellaneous record book begun by the Chancellery in 1291 in order to compile documents of interest to the monarchy (currently, with the reference ACA,CHANCELLERY,Registers,No. 25, folios 159v.-160r.) The statute ordered that four copies of the privilege be deposited, one each, respectively, in the Royal Archive (the current Archives of the Crown of Aragon) and in the municipal councils of Barcelona, Valencia and Zaragoza. This order was carried out, as indicated by the registry notes of the Chancellery. Pere Miquel Carbonell saw the Royal Archive's parchment, as he himself wrote in his Chroniques de Espanya [Chronicles of Spain], Barcelona, 1546, folio 45v.: “de la qual unio hi ha recondite en lo Real Archiu de Barcelona un privilege ho instrument ab segell real pendent plumba e fermat per lo rey en Jacme segon, datum Tarracone nonodecimo chalendas januarii anno domini M.CCC.nonodecimo.” Nevertheless, the original parchment of the Royal Archive was not preserved. Nor was its Zaragoza counterpart. Conversely, the copies that were dispatched to Barcelona and Valencia have been preserved, although their seal is missing. That of Barcelona can be found in the Historical Archive of the City (M. Cinta Mañé, Catàleg dels pergamins municipals de Barcelona. Anys 885-1334 [Catalogue of municipal parchments of Barcelona. Years 885-1334], vol. I, Barcelona, 2005, doc. 297, with the reference IA-289) and that of Valencia in the Municipal Archive of Valencia, (Privileges of James II, No. 16).