Since 1310, after the conspiracy of Bajamonte Tiepolo against the Doge Pietro Gradenigo and the Serenissima, different “boche de leon” were created. A “Boca de Leon” is an official letter box for the citizens to secretly press charges for multiple crimes, ranging from tax evasion to blasphemy or even conspiracies.
The “Boche de leon”, literally “lion mouths”, were called like that because of the figure carved on the letterbox: typically a lion with an open mouth where to place the letters. They were nested in the walls close to the Magistracy, the Doge Palace or a church, making the letters accessible only by the chief district, upon obtaining the keys from the Magistracy.
Venetians were allowed to press charges directly or even completely anonymously. In the case of anonymous letters, from 1387 the Consiglio dei Dieci, a Council of 10 people in charge of the protection of the Serenissima, created as an answer to the failed conspiracy, would proceed with the charges only if they, the Doge and his counselors, would agree on examining the case. For further guarantees against false reporting, in 1542 a new law was voted, making the anonymous charges acceptable only if they contained the names of 3 witnesses.
When a case was examined, the investigation was always carried out extremely carefully and in detail, guaranteeing every right to the defendant until proven guilty. This comes as no surprise since Venice was often represented in allegories by the deity Justice, a virtue which was one of the greatest qualities and pride of the Serenissima.
PS: the Boca de Leon on this picture can be found inside of the Palazzo Ducale