The Herem of Rabbenu Gershom (, ; commonly abbreviated , ) is the name given in Jewish law to a group of ordinances ascribed to Rabbeinu Gershom ben Judah of Mainz ( 960–1028) and enforced by the sanction of ḥerem, or communal excommunication. The two best known forbid a married man to take a second wife, and forbid a husband to divorce his wife without her consent. A prohibition on reading another person's correspondence and a rule protecting Jews who had been forcibly baptised and had returned to Judaism are usually counted with them, and a longer list of communal and procedural ordinances circulated in medieval Ashkenaz under Gershom's name. The whole group is also called the takkanot of Rabbeinu Gershom, while the phrase "ban of Rabbeinu Gershom" is often used more narrowly of the prohibition of polygyny.
Because Talmudic law permitted a man to marry more than one wife and allowed him to divorce his wife against her will, the first two ordinances reversed settled rules of Jewish marriage law, and they are generally regarded as among the most consequential enactments in the history of Jewish family law. No text of the ordinances survives from Gershom's lifetime; the earliest datable references are roughly a century later, and scholars since the nineteenth century have disagreed over which of the rules he actually enacted, with the result that modern writers normally speak of ordinances "attributed to" him.
The ban was received as binding in Germany and northern France and, later, in Poland and the rest of Ashkenaz, but not in Spain, North Africa or most of the communities of the Islamic world, where Sephardi and Middle Eastern Jews restrained polygyny instead through clauses written into the marriage contract. A claim that the ban had been imposed only until the end of the fifth millennium of the Hebrew calendar (the year 1240 CE) was reported by Solomon ben Adret and entered the standard codes, but Ashkenazi authorities held that the prohibition had in any case become binding custom. Where it worked hardship, rabbinic courts developed a dispensation known as the heter meah rabbanim, a release approved by one hundred rabbis of three different countries.
In the modern period the ordinances have been both extended and contested. The Chief Rabbinate of Israel enacted in 1950 that no Jew in Israel, of whatever community, might marry a second wife without a permit signed by the chief rabbis; Israeli law made bigamy a criminal offence subject to such a rabbinical permit; and the rule against opening another's letters has been invoked in discussions of privacy, from the background to Israel's privacy legislation to contemporary debate about electronic communication.
Background
Polygyny and divorce in earlier Jewish law Classical rabbinic law permitted polygyny. The Babylonian Talmud records the ruling of Rava that "a man may marry several wives in addition to his first wife", subject only to his being able to support them all, although the same passage preserves the stricter opinion of Rabbi Ami, who held that a husband who took an additional wife must divorce the first and pay her marriage settlement.Babylonian Talmud, Yevamot 65a. The permission was not used everywhere to the same degree: plural marriage appears to have been uncommon among the Jews of Christian Europe and more frequent in the lands of Islam, where it matched the surrounding legal culture.
Divorce was similarly asymmetrical. A bill of divorce took effect only if the husband gave it willingly, but it did not require the wife's agreement; as Maimonides summarised the rule, a man "divorces only of his own will", whereas a woman "may be divorced either with her consent or without it".Mishneh Torah, Hilkhot Gerushin 1:2. The husband's unilateral power of divorce, derived from Deuteronomy 24:1, is the background against which the second of Gershom's ordinances was framed.
Rabbeinu Gershom and the Rhineland communities Gershom ben Judah was born at Metz in about 960 and died at Mainz in 1028. He headed the academy at Mainz, the principal centre of Talmudic study in the German lands, and later generations knew him by the epithet ("Light of the Exile"); rabbinic scholars in western Europe after him regarded themselves as the students of his students. His authority rested less on any office than on the standing of his school, and it was exercised over a network of Rhineland communities that had begun in his lifetime to legislate for themselves through assemblies of their leaders.
Gershom's own life was touched by the pressures the ordinances address. His son abandoned Judaism at the time of the expulsion of the Jews from Mainz in 1012, and Gershom is reported to have observed the customary rites of mourning when he died a Christian.
The ordinances
Prohibition of polygyny The most widely known of the ordinances forbids a man to marry an additional wife while married to his first.Finkelstein (1924), p. 23. It is cast as a ḥerem: the sanction for breach is exclusion from the community rather than invalidity of the marriage, and a second marriage contracted in defiance of the ban was treated as legally effective, so that it could be ended only by a bill of divorce. The prohibition is stated in the Shulḥan Arukh in a single clause, "Rabbeinu Gershom placed under ban one who marries a wife in addition to his wife", to which Moses Isserles appended a long gloss on its limits and its acceptance.Shulḥan Arukh, Even ha-Ezer 1:8–10, with the glosses of Moses Isserles.
Divorce only with the wife's consent The second ordinance forbids a husband to divorce his wife against her will. Asher ben Jehiel preserved a rationale for it: Gershom, he wrote, saw a generation that had grown unrestrained and was degrading Jewish women by the casual tossing of a bill of divorce, and therefore legislated "to equalise the power of the woman to the power of the man".Responsa of Rabbeinu Asher 42:1. Isserles records the rule together with its standard exception: a husband may not divorce his wife without her consent even if he is willing to pay her marriage settlement in full, "unless she has transgressed the religious law".Shulḥan Arukh, Even ha-Ezer 119:6, gloss of Moses Isserles. Finkelstein notes a further procedural rule ascribed to Gershom for the Rhine communities, that no divorce was to be executed without the consent of the representatives of the communities.Finkelstein (1924), p. 30.
The two matrimonial ordinances are closely linked. Avraham Grossman argues that the rule on divorce was framed to close the gap left by the rule on polygyny: without it, a merchant who wished to marry abroad could simply send a bill of divorce to the wife he had left behind in Germany. Susan Weiss observes that the protection was real but incomplete, since rabbinic courts retained means of overriding a wife's refusal.
Privacy of correspondence A third ordinance forbids reading another person's letters without permission. Finkelstein observed that in a period without a public postal service letters travelled with private messengers and fellow travellers, so that the rule met a practical need, and that it was among the ordinances most frequently cited in later centuries in continental Europe.Finkelstein (1924), p. 31. Ashkenazi correspondents came to write the abbreviation , for "under the ban of Rabbeinu Gershom", on a sealed letter as a warning that it was not to be opened by anyone but the addressee.
Returning apostates A fourth ordinance forbids taunting or reproaching a Jew who had been baptised and had subsequently returned to Judaism. Finkelstein notes that its protection extended beyond those converted by physical force to those who had been induced to leave the community by other means. This is the one ordinance whose attribution is generally regarded as secure, because Rashi cites it in Gershom's name.
Other ordinances ascribed to Gershom Medieval sources ascribe to Gershom a considerably longer list. Rabbeinu Tam attributes to him a ruling against altering the text of the Talmud by conjectural emendation. Finkelstein groups a further set as a miniature constitution for the Rhineland communities: the local court's jurisdiction extends to Jews passing through and not only to residents; a plaintiff may halt the synagogue service to press a claim, but only after three public complaints; the owner of a synagogue may not exclude individual members while keeping it open to others; an individual may proclaim a ban requiring anyone who has found lost property to declare it; and an ordinance adopted by the majority of a community binds all its members.Finkelstein (1924), pp. 32–34. A rule protecting Jewish tenants against eviction is also counted among them.Finkelstein (1924), pp. 30–34.
Transmission and attribution
The evidence No text of the ordinances survives from Gershom's own time, and no scholar of his generation quotes them. Finkelstein noted that for the ban on polygyny "the text of the ordinance has not been preserved", and that there is no reference to it before the age of Rashi, almost a century after it was supposedly promulgated.Finkelstein (1924), pp. 23, 29. The ascriptions that do survive are later: Meir of Rothenburg in the thirteenth century and a series of fifteenth-century authorities transmit lists of "the ordinances of Rabbeinu Gershom", and compilations such as the Kol Bo preserve them in varying versions.
The ordinances also circulated as part of the legal corpus of the Rhineland communities. In Rainer Barzen's critical edition of the ordinances of Speyer, Worms and Mainz, known as the Taqqanot Qehillot ShUM, the early Rhenish material falls into four groups: enactments authorised by the three communities themselves; ordinances attributed to Rabbeinu Gershom; an ordinance on levirate marriage by David of Münzenberg; and ordinances of Rabbeinu Tam. Grossman notes that the ordinances attributed to Gershom were in any event re-approved and accepted as binding at later assemblies of the sages of Ashkenaz, which is how they acquired their force for subsequent generations.
Modern scholarship Scholars have divided over how much of the corpus is genuinely Gershom's. The Encyclopaedia Judaica summarises the sceptical case: no original texts survive, contemporaries are silent, the ascriptions surface only generations later, and some rules may have been credited to Gershom posthumously in order to lend his prestige to communal regulations of later date; on this view the ban on divorce without consent in particular, and several of the other ordinances, may not really be his. Against this, Finkelstein's study of the medieval synods treated the ordinances as the work of a genuine assembly convened by Gershom and as the foundation of a durable federation of communities.
A more recent proposal, set out in a working paper by the communications historian Menahem Blondheim, reads the corpus as a coherent body of rules governing communication across the diaspora (travel, hospitality, correspondence and the flow of information between autonomous communities) rather than as a miscellany of unrelated rules, and sees in it a response to the legal vacuum between self-governing communities at a time of increasing Jewish migration and commerce.
Modern reference works accordingly describe the rules as ordinances attributed to Gershom, while noting that the dispute over authorship has had no practical effect on their standing in Jewish law, which rests on their acceptance by the communities.
Explanations Historians have proposed several overlapping explanations for the two matrimonial ordinances.