Oregon Revised Statutes Procedure in Criminal Matters Generally § 135.380

(1) A defendant shall not be required to plead to an offense punishable by imprisonment until the defendant is represented by counsel, unless the defendant knowingly waives the right of the defendant to counsel.

(2) A defendant may plead guilty or no contest on the day of arraignment or any time thereafter except that a defendant without counsel shall not be allowed to plead guilty or no contest to a felony on the day of arraignment.

(3) Upon completion of the arraignment, unless the defendant enters a plea in the manner provided in ORS 135.305 to 135.325, 135.335, 135.355, 135.360 and 135.375, the defendant shall be considered to have entered a plea of not guilty.