The essay aims to analyse a case of institutional conflict in 15th century Sardinia, under the government of the Crown of Aragon, in order to explain the relations between different levels of power. The subject is a complex judiciary suit, started in 1467 and involving royal officers, baronial families and the urban government of Cagliari, about a great sum of money that the Da Sena family owed to a Catalan-Sardinian merchant. Town magistrates, in particular, proved to be very skilful in allying with the royal representatives against the interests of feudal families; on the other hand, the consiglieri of Cagliari and even the local Locumtenens used the advise of urban lawyers to defend their privileges agains the authoritarian efforts of the Crown. The fact that the documentary records of the case were copied for the Cagliari town archives is a clear example of how the written record could become a symbol of municipal purposes.
Keywords: Sardinia, Crown of Aragon, institutional conflicts, arhives, written records