In this paper we study a fight between two groups with significant social power, which came to light in Cartagena de Indies during Lent in1756. The matter was resolved by the Council of the Indies, after three years of inquiries with numerous witnesses and intrigues leading authorities pledged to the Viceroyalty of New Granada. The case transcended as an affair and was judged as a public sin and criminal offense, but it really was originated in a dispute over control of the transatlantic slave trade. So that the extensive dossier which resulted in the indictments, research, advocacy and conviction, in addition to the circumstances of context, has allowed us to make an approach to the functioning of the justice of the king in typical conflicts of that time. Keywords: justice, slave trade, scandal, politics, public sins.