Talmudic legislation prescribed penalty for a Jew to testify in a non-Jewish court, against a fellow Jew, to benefit a gentile - for breach of a duty of loyalty to a fellow Jew. Through close textual analysis, Saul Berman explores how Jewish jurists responded when this virtue of loyalty conflicted with values such as Justice, avoidance of desecration of God's Name, deterrence of crime, defence of self, protection of Jewish community, and the duty to adhere to Law of the Land. Essential for scholars and graduate students in Talmud, Jewish law and comparative law, this key volume details the nature of these loyalties as values within the Jewish legal system, and how the resolution of these conflicts was handled. Berman additionally explores why this issue has intensified in contemporary times and how the related area of 'Mesirah' has wrongfully come to be prominently associated with this law regulating testimony.