Omerta

Omertà /oʊˈmɛərtə/ (Italian pronunciation: [omerˈta]) is a code of honor that places importance on silence, non-cooperation with authorities, and non-interference in the illegal actions of others. It originated and remains common in Southern Italy, where banditry and the Mafia-type criminal organizations (like the Camorra, Cosa Nostra, 'Ndrangheta and Sacra Corona Unita) are strong. It is also deeply rooted in rural Crete (Greece), and Corsica.

It also exists, to a lesser extent, in certain Italian-American neighborhoods where the Italian-American Mafia has influence—and Italian ethnic enclaves in countries such as Germany, Canada, and Australia, where Italian organized crime exists. Retaliation against informers is common in criminal circles, where informers are known as "rats" or "snitches".

Omertà implies "...the categorical prohibition of cooperation with state authorities or reliance on its services, even when one has been victim of a crime." A person should absolutely avoid interfering in the business of others and should not inform the authorities of a crime under any circumstances (though if justified he may personally avenge a physical attack on himself or on his family by vendetta, literally a taking of revenge, a feud). Even if somebody is convicted of a crime he has not committed, he is supposed to serve the sentence without giving the police any information about the real criminal, even if that criminal has nothing to do with the Mafia. Within Mafia culture, breaking omertà is punishable by death.

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Wikipedia