(lit. "decree, edict"; pl. gezerot). Hebrew term with several meanings in different contexts. Some major instances are: (1) A Divine command for which no reason is given, such as the Red Heifer (Num. 19), concerning which the Midrash quotes God as saying, "I have decreed a gezerah, and you have no right to question it" (Num. R. 19:4). Similarly, when God refuses to reveal the time appointed for someone's death (Shab. 30a), or does not explain why righteous people suffer martyrdom, He is said to declare: "It is a gezerah issued by Me" (ibid.). (2) An edict promulgated by a foreign ruler banning the observance of Jewish law. Such decrees were issued by Antiochus IV Epiphanes in the Hasmonean era, and by the Roman Emperor Hadrian in the days of R. Akiva. (3) A synonym for organized forced conversion, religious persecution, massacres, and pogroms. Two notable examples of this usage are gezerot tatnu (lit. decrees of the year 4856 = 1096 CE), referring to the annihilation of Jewish communities (particularly in the Rhineland) during the First Crusade; and gezerot taḥ ve-tat (decrees of 5048-9 = 1648-9), the wholesale massacre of Jews in Poland and the Ukraine during the Cossack uprising led by Bogdan Chmielnicki. (4) A restrictive or preventive measure enacted by rabbinical authorities with the aim of safeguarding the observance of Scriptural law, in keeping with the admonition of the Men of the Great Assembly to "make a fence [Heb. seyag] around the Torah" (Avot 1:1). Among the early ordinances of this type are the "18 gezerot" adopted by the disciples of Hillel and Shammai at the beginning of the first century CE (TB Shab. 11a-17b; TJ Shab. 1:4, 3c). These were designed to strengthen the barriers between Jews and non-Jews, particularly in regard to sexual morality, and to uphold the laws of ritual cleanness. Other restrictive measures were devised to safeguard observance of the Sabbath and festivals.
The sages did think it necessary to limit such restrictions. For example, they stipulated that "a gezerah should not be imposed on the community if the majority is able to comply with it" (Av. Zar. 36a). However, once a gezerah is decreed by the proper authorities and widely accepted by Jews, no subsequent authority can rescind it (ibid.). Furthermore, even if the reason prompting an earlier authority to adopt a gezerah no longer applies, the decree may not be canceled without a specific proclamation of annulment by a later authority (Béts. 5a-b). Some halakhic authorities nevertheless maintain that if it is clear that the gezerah would not have been enacted under present circumstances, such a decree becomes null and void of itself (Menahem ha-Meiri, Bet ha-Beḥirah to Bétsah 5a). Thus, many of the restrictions imposed by the sages against commerce with non-Jews only applied to the ancient idolators, and not to Christians and Muslims, who do not worship idols (Tos. to Av. Zar. 2a).
Restrictions added to Jewish law by post-talmudic authorities are usually styled ḥerem (lit. "excommunication") and include the Ashkenazi regulation banning polygamy which is known as ḥerem de-Rabbenu Gershom (see Gershom Ben Judah Me'or ha-Golah; Takkanah). Other post-talmudic measures, such as the Ashkenazi rule prohibiting the consumption of legumes (Kitniyyot) on Passover, fall under the category of minhag (local Custom) and are not observed by all Jewish communities.
