There are two types of retaliation eviction. The first kind is known as statutory retaliation and the second is common law retaliation.
The landlord has burden of proving the basis for the eviction, e. g., nuisance. What happens if the landlord’s alleged reason for eviction is not legitimate? If the tenant can show a legal exercise of her rights, the tenant may prevail because she has shown retaliation. This is a complete defense to an unlawful detainer. For example, if the tenant notifies the Department of Building Inspection about housing code violations. The landlord is cited by the Building Inspector. If the landlord then serves the tenant with a three-day notice to quit and an unlawful detainer within 180 days after the landlord has been notified by Department of Building Inspection, the tenant will be able to prove retaliation by the landlord.
It is still an unresolved issue if the landlord can show a legitimate good faith reason for eviction. Tenants typically argue that any retaliation by the landlord is prohibited under California laws. If a tenant shows retaliation is overall a substantial or motivating factor, then the tenant should prevail. However, landlords argue that even if the landlord had both legitimate and retaliatory motives, then the landlord would prevail. This type of mixed motive retaliation has not been resolved by the courts.