The Talmudic laws of mesira prohibited Jews from informing against other Jews to non-Jewish authorities. This ancient “no snitching” rule is getting modern attention in the Los Angeles case of Rabbi Moshe Zigelman, an Orthodox jew who is refusing to testify against other Jewish suspects before a grand jury regarding alleged acts of tax fraud and money laudering. Story here: Jewish law goes to court: Mesira meets American justice. The story describes the Talmudic issue this way:
The concept of mesira, which literally means “delivery,” dates back to periods when governments often were hostile to Jews and delivering a Jew to the authorities could lead to an injustice and even death. The rules of mesira still carry force within the Orthodox world, owing both to the inviolability of the concept’s talmudic origins and the insular nature of many Orthodox communities. But they are also the subject of debate over whether the prohibition applies in a modern democracy that prides itself on due process and civil rights.
This dispute dovetails with a large issue in criminal justice: what happens to the force of criminal law when people believe it is unfair or leads to injustice? Professor Tom Tyler has written extensively about the fact that people are more likely to obey the law if they perceive it to be be fair and carried out through evenhanded and respectful procedures. See, e.g., Tom Tyler & Jeffrey Fagan, Legitimacy and Cooperation: Why Do People Help the Police Fight Crime in Their Communities?, 6 Ohio St. J. of Criminal Law 231 (2008).