Oregon Revised Statutes Revenue and Taxation § 316.158

(1) It is the intent of the Legislative Assembly that no part of ORS 316.157 be the law if any part of ORS 316.157 is held to be invalid or unconstitutional. However, no amended return or payment of additional taxes shall be required for any year prior to the year in which any part of ORS 316.157 is held to be invalid or unconstitutional by a court of last resort.

(2) Except as provided in subsection (1) of this section, it is the intent of the Legislative Assembly that the provisions of this section and ORS 238.445, 316.087, 316.157, 316.680 and 316.695 be severable as provided in ORS 174.040.