Oregon Revised Statutes Crimes and Punishments § 163.135

(1) It is an affirmative defense to murder for purposes of ORS 163.115 (1)(a) that the homicide was committed under the influence of extreme emotional disturbance if the disturbance is not the result of the person's own intentional, knowing, reckless or criminally negligent act and if there is a reasonable explanation for the disturbance. The reasonableness of the explanation for the disturbance must be determined from the standpoint of an ordinary person in the actor's situation under the circumstances that the actor reasonably believed them to be. Extreme emotional disturbance does not constitute a defense to a prosecution for, or preclude a conviction of, manslaughter in the first degree or any other crime.

(2) The defendant may not introduce in the defendant's case in chief expert testimony regarding extreme emotional disturbance under this section unless the defendant gives notice of the defendant's intent to do so.

(3) The notice required must be in writing and must be filed at the time the defendant pleads not guilty. The defendant may file the notice at any time after the defendant pleads but before trial if the court determines that there was just cause for failure to file the notice at the time of the defendant's plea.

(4) If the defendant fails to file notice, the defendant may not introduce evidence for the purpose of proving extreme emotional disturbance under ORS 163.115 unless the court, in its discretion, determines that there was just cause for failure to file notice.

(5) After the defendant files notice as provided in this section, the state may have at least one psychiatrist or licensed psychologist of its selection examine the defendant in the same manner and subject to the same provisions as provided in ORS 161.315.