ORS § 90 § 90.385

(1) Except as provided in this section, a landlord may not retaliate by increasing rent or decreasing services, by serving a notice to terminate the tenancy or by bringing or threatening to bring an action for possession after:

(a) The tenant has complained to, or expressed to the landlord in writing an intention to complain to, a governmental agency charged with responsibility for enforcement of any of the following concerning a violation applicable to the tenancy:

(A) A building, health or housing code materially affecting health or safety;

(B) Laws or regulations concerning the delivery of mail; or

(C) Laws or regulations prohibiting discrimination in rental housing;

(b) The tenant has made any complaint to the landlord that is in good faith and related to the tenancy;

(c) The tenant has organized or become a member of a tenants’ union or similar organization;

(d) The tenant has testified against the landlord in any judicial, administrative or legislative proceeding;

(e) The tenant successfully defended an action for possession brought by the landlord within the previous six months except if the tenant was successful in defending the action only because:

(A) The termination notice by the landlord was not served or delivered in the manner required by ORS 90.155; or

(B) The period provided by the termination notice was less than that required by the statute upon which the notice relied to terminate the tenancy;

(f) The tenant uses, or intends or attempts to use, the dwelling as a family child care home in compliance with ORS 90.358; or

(g) The tenant has performed or expressed intent to perform any other act for the purpose of asserting, protecting or invoking the protection of any right secured to tenants under any federal, state or local law.

(2) As used in subsection (1) of this section, “decreasing services” includes:

(a) Unreasonably restricting the availability of or placing unreasonable burdens on the use of common areas or facilities by tenant associations or tenants meeting to establish a tenant organization; and

(b) Intentionally and unreasonably interfering with and substantially impairing the enjoyment or use of the premises by the tenant.

(3) If the landlord acts in violation of subsection (1) of this section the tenant is entitled to the remedies provided in ORS 90.375 and has a defense in any retaliatory action against the tenant for possession.

(4) Notwithstanding subsections (1) and (3) of this section, a landlord may bring an action for possession if:

(a) The complaint by the tenant was made to the landlord or an agent of the landlord in an unreasonable manner or at an unreasonable time or was repeated in a manner having the effect of unreasonably harassing the landlord in consideration of all related circumstances preceding or contemporaneous to the complaint;

(b) The violation of the applicable building or housing code was caused primarily by lack of reasonable care by the tenant or other person in the household of the tenant or upon the premises with the consent of the tenant;

(c) The tenant was in default in rent at the time of the service of the notice upon which the action is based; or

(d) Compliance with the applicable building or housing code requires alteration, remodeling or demolition which would effectively deprive the tenant of use of the dwelling unit.

(5) For purposes of this section, a complaint made by another on behalf of a tenant is considered a complaint by the tenant.

(6) For the purposes of subsection (4)(c) of this section, a tenant who has paid rent into court pursuant to ORS 90.370 shall not be considered to be in default in rent.

(7) The maintenance of an action under subsection (4) of this section does not release the landlord from liability under ORS 90.360 (2).