Judaism possesses a concept that bears striking functional similarities to the Italian Mafia’s omertà, the well-known code of silence that forbids informing on fellow members. Omertà is a code of silence and refusal to cooperate with legal authorities that forms a central pillar of southern Italian organized crime, enforced by intimidation, fear, and dishonor.
While omertà protects criminal enterprises, the Jewish concept of mesirah (Hebrew for “handing over”) arose from a different historical necessity: protecting Jewish minorities from gentile authorities. Mesirah prohibits Jews from reporting fellow Jews to non-Jewish authorities, creating a parallel system of internal loyalty and silence that has operated within Jewish communities for millennia.
According to traditional Jewish law, mesirah is the forbidden action of one Jew reporting the conduct of another Jew to non-rabbinic authorities in circumstances prohibited by Jewish law. This prohibition extends to both turning over a person and their property. The prohibition covers both the person and the property, a point the Shulchan Aruch makes in Choshen Mishpat 388 when it forbids handing over a fellow Jew “be it his person or his money.” A Jew who violates it is a moser, an informer, and the historical consequences were severe. Medieval Jewish tribunals in Spain sometimes branded informers or, for repeat offenders, put them to death, and in 19th century Russia a moser was occasionally found drowned in a river.
The prohibition of mesirah runs deep in Jewish law, set down in the Babylonian Talmud and sharpened by medieval codifiers.
American Buddhist Net 