2011 ORS § 161.255¹
Use of physical force by private person making citizens arrest
(1) Except as provided in subsection (2) of this section, a private person acting on the persons own account is justified in using physical force upon another person when and to the extent that the person reasonably believes it necessary to make an arrest or to prevent the escape from custody of an arrested person whom the person has arrested under ORS 133.225 (Arrest by private person).
(2) A private person acting under the circumstances prescribed in subsection (1) of this section is justified in using deadly physical force only when the person reasonably believes it necessary for self-defense or to defend a third person from what the person reasonably believes to be the use or imminent use of deadly physical force. [1971 c.743 §31; 1973 c.836 §339]