Legal Question in Landlord & Tenant Law in Washington

Re: tenant law

No. Landlords don't have the right to ban guests. They can, however, issue their tenant a notice to comply with lease terms or, possibly, a notice to vacate for nuisance, but that is tough to prove.

You are right that hearsay is part of the equation. If the landlord observes drug/alcohol behavior, he can call the police. If somebody tells the landlord something, the landlord has to decide what sort of notice to issue to the tenant.

The landlord can also evict for having overnight guests.

Hope this helps. Elizabeth Powell