Odger's English Common Law

POSSESSION.
'447
One main distinction between an action of trespass to land
and au action for recovery of land is that in the former action
the plaintiff is always in possession and the defendant is
always oat of possession ; whereas in the latter action the
positions are reversed.
A man is said to be in possession of land whenever he has
full and uncontrolled physical dominion over it. Thus, he is
in possession of a house when he or his servants are living in
it ; if he or they are absent from it, he would still be held to
be in possession if such absence was only temporary, or if he
could return and re-enter at any moment, if he chose, without
asking any one's permission and without any preliminary
ceremony. But directly any other person enters into and
remains on the premises without his consent, the former
possessor is ousted ; for two persons cannot be in possession
of the same property at the same time, unless they be joint
occupiers or tenants in common.
A mere right to the possession of land will not entitle the
plaintiff to bring an action of trespass without entry. But
actual entry, with sufficient title, on any part of the land for
the purpose of taking possession of the whole is sufficient to
vest possession of the whole in the lawful owner, and to make
all persons previously in possession of any part of the land
who remain there, and all who afterwards enter on any part
of it, without his permission, trespassers. A man who has a
good title to the possession of land, but who in fact is out of
possession, must bring an action for the recovery of land and
not an action of trespass. But as soon as such a man enters
on any part of the land, he will be deemed in law to have
taken possession of the whole as against those who show no
title. 1
Thus a person, to whom a lease has been granted but who has never
been in possession of the property, cannot bring an action of trespass
(though he can bring an action for recovery of land). Again, before
entry neither a freeholder, nor the customary heir of a copyhold tenement,
nor the assignee of a term of years can bring an action of trespass for an
unlawful entry on the land. Nor can a mortgagee, who has never been in
1 Per Lord Blackburn in Bristow v. Cormiaan (1878), 3 App. Cas. at p. 661.