ORS § 80.010
Any bona fide assignment of a chose in action by way of sale or pledge made in writing for a good, valuable and adequate consideration is deemed completed at the time the writing is executed by the assignor and takes effect at the time of execution according to the terms of the writing without the giving of notice to the debtor therein mentioned unless such notice is required by statute; but if notice is not given to a debtor, and such debtor, without knowledge of the assignment pays or discharges in whole or in part the obligation of the debtor to the assignor or to any subsequent assignee of the chose in action who has given notice, such payment constitutes a discharge of the debtor to the extent thereof without prejudice to any right or remedy between the several assignees.
ORS 80.010