10 Cal.3d 616 Supreme Court of California, In Bank. Roger GREEN, Petitioner, V. The SUPERIOR COURT OF the CITY AND COUNTY OF SAN FRANCISCO, Respondent; Jack SUMSKI, Real Party in Interest. S.F. 22993- Jan. 15, 1974-Synopsis Petition for writ of mandate to compel Superior Court to vacate judgment rendered against petitioner in unlawful detainer action. The Supreme Court, Tobriner, J., held that warranty of habitability is implied by law in residential leases; breach of such warranty may be raised as defense in unlawful detainer action and that case must be remanded to trial court so that it might determine whether landlord had breached the implied warranty of habitability as alleged by tenant. Peremptory writ of mandate issued.We begin with a brief review of the facts of the instant case, which reveal a somewhat typical unlawful detainer action. On September 27, 1972, the landlord Jack Sumski commenced an unlawful detainer action in the San Francisco Small Claims Court seeking possession of the leased premises and $300 in back rent. The tenant admitted non-payment of rent but defended the action on the ground that the landlord had failed to maintain the leased premises in a habitable condition. The small claims court awarded possession of the premises to the landlord and entered a money judgment for $225 against the tenant. The tenant then appealed the decision to the San Francisco Superior Court, where a de novo trial was held pursuant to section 117j of the Code of Civil Procedure. In support of his claim of uninhabitability, the tenant submitted a copy of an October 1972 inspection report of the San Francisco Department of Public Works disclosing some 80 housing code *621 violations in the building in question, as well as an order of the department scheduling a condemnation hearing for January 19, 1973. In addition, in testimony at trial, petitioner and his roommate detailed a long list of serious defects in the leased premises which had not been repaired by the landlord after notice and which they claimed rendered the premises uninhabitable. Some of the more serious defects described by the tenants included (1) the collapse and non- repair of the bathroom ceiling, (2) the continued presence of rats, mice, and cockroaches on the premises, (3) the lack of any heat in four of the apartment's rooms, (4) plumbing blockages, (5) exposed and faulty wiring, and (6) an illegally installed and dangerous stove.' The landlord apparently did #*#707 #*1171 not attempt to contest the presence of serious defects in the leased premises, but instead claimed that such defects afforded the tenant no defense in an unlawful detainer action.5. Conclusion. We have concluded that a warranty of habitability is implied by law in residential leases in this state and that the breach of such a warranty may be raised as a defense in an unlawful detainer action. Under the implied warrantyr which we recognize, a residential landlord covenants that premises he leases for living quarters will be maintained in a habitable state for the duration of the lease. This implied warranty of habitability does not require that a landlord ensure that leased premises are in perfect, aesthetically pleasing condition, but it does mean that 'bare living requirements' must be maintained}: mm \"1183 In most cases substantial compliance with those applicable building and housing code standards which materially affect health and safety will suffice to meet the landlord's obligations under the common law implied warranty of habitability we now recognize.23 As the Hinson court *638 observed: '(mJinor housing code violations standing alone which do not affect habitability must be considered tie tumours and will not entitle the tenant to reduction in rent. . . .' {26 Cal.App.2d at p. 1'0, 102 Cal_Rptr_ at p. 666.]