A landlord may not legally retaliate by increasing rent, decreasing services, serving an eviction notice, threatening eviction, or filing an eviction case after a tenant:
1. Has made any good faith complaint to the landlord about the tenancy [about the need for repair or a violation of the rental agreement]; or
2. Complains to certain code enforcement agencies; or
3. Joins or organizes a tenants' union; or
4. Testifies against the landlord in court; or
5. Wins in an FED case within the previous six months, unless the win was based on a technicality; or
6. Does something or says that the tenant will do something to assert the tenant's rights under any law.
Tenants may sue for retaliation and may ask for twice the actual damages or up to two months' rent, whichever is more. It is usually a defense to an eviction based on a 30-day notice without cause if you can prove the notice was given in retaliation. But retaliation may not keep you from being evicted if you owed rent when the notice was given, if the code violations were caused by the tenant or guests, if you made repeated or harassing complaints, and when repairs needed for code compliance cannot be made without forcing the tenant to move. Contact a lawyer before using retaliation as a defense or claim because it can be a complicated issue. A landlord is likely to give a non-retaliatory explanation for the notice. ORS 90.385