A quick definition of ejectione firmae:

Definition: Ejectione firmae is a legal term that refers to a writ or action of trespass used to recover lands or tenements that were leased for a term of years and then taken away by the lessor, reversioner, remainderman, or a stranger. The lessee, or the person who leased the property, can use this writ to recover their term or the remainder of it, along with damages. This action is the basis for the modern action of ejectment.