Oregon Revised Statutes Procedure in Criminal Matters Generally § 136.770

(1) When an enhancement fact relates to an offense charged in the accusatory instrument, the court shall submit the enhancement fact to the jury during the trial phase of the criminal proceeding unless the defendant:

(2) If the defendant makes the election under subsection (1)(b)(B) of this section and is found guilty during the trial phase of the criminal proceeding, the enhancement fact shall be tried during the sentencing phase of the proceeding.

(3) If there is more than one enhancement fact relating to the offense and the defendant does not admit to all of them, the defendant shall elect to try to the jury or to the court all enhancement facts relating to the offense to which the defendant does not admit.

(4) If the court finds that trying an enhancement fact relating to the offense during the trial phase of the criminal proceeding would unfairly prejudice the jury's verdict on an underlying offense, the court shall allow the defendant to defer trial of the enhancement fact to the sentencing phase of the proceeding without waiving the right to a jury trial on the enhancement fact.

(5) If two or more defendants are being tried in the same criminal proceeding, each defendant shall make the elections required by this section.