The betrothal and wedding did not always take place in one ceremony and at the same time. In Talmudic and Geonic (7th to 11th centuries) times, these were separate ceremonies. First, a betrothal ceremony took place in which the man gave his wife a ring (or a different object) and said to her "You are hereby betrothed unto me by means of this ring according to the laws of Moses and Israel". Then, the ketubah was signed. After the betrothal each spouse would continue living on their own - they were neither allowed to be sexually intimate nor meet each other privately. The wedding served as a festive ceremony that marked the wife’s entry into her husband’s home. If the bride was a virgin, the wedding would take place 12 or more months following the betrothal. If the bride was a widow, the wedding would take place 30 days after the betrothal. In both cases, a get was required to dissolve a betrothal. The betrothal was conditional in certain difficult situations so that the court could cancel it in case obtaining a get was problematic.
Today, both ceremonies take place together, under the bridal canopy (huppah). Nowadays the engagement has replaced the traditional betrothal ceremony - it does not obligate the couple according to Jewish law. During the Mishnah and Talmud periods, conditions could be added at the time of betrothal. If, for some reason these conditions weren’t met, the betrothal could be annulled without a get. However, the Talmud is not clear regarding conditional weddings. For example, in Yebamot 107a it states, “there is no condition in marriage” (it can be understood to be a rhetorical statement in that context, from which we do not necessarily glean a judgment on conditional marriages). This statement can be understood to mean that conditions apply only to the time between the betrothal and the wedding.
Some decisors used conditional marriage as a method to help solve halakhic problems. For example, in the 15th century, Rabbi Israel Isserlein and his pupil Rabbi Israel of Bruna applied this solution in similar cases: a widow whose husband died while they were childless and she therefore had to get halitzah [a ceremony in which she was released] from his brother in order to remarry]. The brother was an apostate, and therefore refused to take part in the ceremony. The well known 18th and 19th century decisors, the Hatam Sofer and the Nodah Beyehudah, followed the opinion of Rabbi Bruna, and in time a condition was accepted that if a husband dies and the wife needs halitzah from an apostate brother, the betrothal is cancelled (the Hatam Sofer expanded the condition to the case of a missing brother).
At the end of the 19th century and the beginning of the 20th century, there were additional attempts to apply conditional marriage in order to solve existing problems surrounding the get. In 1907, following civil marriages in France, some Jewish men divorced their wives in civil courts without giving them a get, the French Rabbis formulated a condition that stated that if a court ruled for divorce and the husband refused to give a get the marriage would be null and void. In 1924 members of the Rabbinic Court in Istanbul proposed that the betrothal should be annulled if the husband left his wife for a long period of time without her permission, if he did not accept the Rabbinic Court ruling to give her a get, if he contracted a contagious or mental disease, if the wife required halitzah from a recalcitrant brother in law or one who lost his memory.
It was difficult to implement these conditions. Firstly, it was difficult to formulate the condition in a way that would be accepted by a wide range of rabbinic authorities. Secondly, many rabbis were opposed in principle to conditional marriages, in contrast to conditional betrothals that had been acceptable in Talmudic times.
In 1966 the Orthodox Rabbi Eliezer Berkovits published T'nai Bi'N'suim u'V'Get (Conditional Marriage and Divorce) that provoked harsh reactions in the Orthodox world.
In 1968 the Conservative movement in the U.S. adopted the conditional marriage solution. In some Conservative ceremonies, the couple is asked to sign an agreement before the huppah in front of a Rabbinic Court that states that the marriage is conditional. The agreement stipulates that if the couple were to obtain a civil divorce and the husband refuses to give his wife a get within 6 months, the marriage would be null and void (a minority of rabbis use this solution, because in cases when a get cannot be obtained, the Conservative movement’s Rabbinic Court performs hafka'at kiddushin – betrothal annulment).