Most jurisdictions read residential leases to include an implied warranty of habitability. This warranty requires landlords to keep their property "habitable," even if the lease does specifically require them to make repairs. Furthermore, the warranty conditions a tenant's duty to pay rent on the landlord's duty to maintain a habitable living space. This makes it easier for tenants to get landlords to make repairs. This warranty is usually coupled with rules prohibiting landlords from retaliating against tenants who complain housing code violations.
This warranty is controversial. Supporters argue that it protects poor tenants from abusive landlords. Detractors argue that it drives up housing prices, encourages landlords to abandon old buildings, and turns landlords into public utilities.