P, tenants, filed a complaint against D, landlord, alleging breach of the warranty of habitability. Ps moved for summary judgment and for judgment on the pleadings, which was denied. Ps appealed, and the parties filed a joint motion to have questions certified to the court: 1. Whether failure of a landlord to maintain rental premises in a habitable condition and otherwise remedy defects to the premises which render the residence uninhabitable is in violation of a landlord's implied warranty of habitability to a tenant? And if so, whether it is subject to waiver? 2. Whether a landlord's warranty of habitability and the tenant's covenant to pay rent are mutually dependent? 3. Whether failure of a landlord to maintain the premises in habitable condition constitutes a failure of consideration and a breach of the rental agreement? 4. Whether a landlord's breach allows to the tenant one or more of the following remedies: (a) a right of action or setoff for the difference between the agreed rent and the fair rental value of the premises in their defective condition; (b) after reasonable notice and opportunity to a landlord to correct the defective conditions, to repair the defects himself and deduct the repair cost from the rent; and (c) vacation of the premises terminating a tenant's obligation to pay rent? (d) what damages, if any, are recoverable by the landlord or tenant in the event of breach by either party. 5. Whether a breach of the implied warranty of habitability is a defense to a landlord's action for rent, damages, or unlawful detainer?