Since land given in fee absolute (outright) was at risk of ultimately passing to collateral heirs or being sold or given away (alienation), it was common practice to ensure that the land remained with the direct heirs by giving it instead in frank-marriage (in liberum maritagium).
Under this system, the donor's daughter and later the children of the marriage would hold the land for three generations free of all feudal services, with the donor or his heirs being able to recover it in the event that the direct family line ended during that period.
[3] Typically, the three-generation rule was not explicitly stated in charters of gift, but apparently grew out of twelfth-century custom.
[3] By the middle of the thirteenth-century, there were concerns that the rule whereby the donor or his heirs could recover the land if the family line failed were proving ineffective.
In 1258 the barons unsuccessfully petitioned the king complaining that nothing was being done to prevent widows without heirs from selling land granted to them in maritagium to third parties.