Illustrative example
Every application someone makes is refused as soon as the agent runs a screening report showing a non-payment case from years ago that was dismissed.
Refusing to rent on the basis that an applicant was involved in a past or pending landlord-tenant action is prohibited, and "involved in" is unqualified - the section does not separate a case won from a case lost, or the tenant who sued from the one who was sued. A rebuttable presumption of violation arises where it is established that the landlord requested information from a tenant screening bureau or otherwise inspected court records and then refused. So it turns on establishing that the report was pulled before the refusal.
The agent agrees to reconsider on income and references alone and to stop asking about housing court history at viewings, and the applicant supplies two landlord references instead.