ORS 161.225 Defense of premises
(1) A person in lawful possession or control of premises is justified in using physical force upon another person when and to the extent that the person reasonably believes it necessary to prevent or terminate what the person reasonably believes to be the commission or attempted commission of a criminal trespass by the other person in or upon the premises.
(2) A person may use deadly physical force under the circumstances set forth in subsection (1) of this section only:
(a) In defense of a person as provided in ORS 161.219; or
(b) When the person reasonably believes it necessary to prevent the commission of arson or a felony by force and violence by the trespasser.
(3) As used in subsection (1) and subsection (2)(a) of this section, “premises” includes any building as defined in ORS 164.205 and any real property. As used in subsection (2)(b) of this section, “premises” includes any building.