Coemptio could be contracted not only with a husband ("for the sake of marriage"), but also with an outsider ("for the sake of trust"). A wife who had become cum manu through the process of coemptio was emancipated upon divorce.
Coemptio, in Roman law, could be used for both a husband and wife to enter into a contract, but also with an outsider, which led to the emancipation of the woman after divorce.