When it can be shown that a landlord has received notice of certain defective conditions in an apartment or the building's common areas for a six-month period, and did nothing to correct them, there is a tenant defense against demands for rent. Several elements are necessary to make this defense work. First, there is a list of "rent-impairing violations" published by the Department of Housing Preservation and Development. One or more of these must be at issue in your case. Mostly these are serious defects involving matters such as fire safety, proper ingress and egress, heat and hot water, sewage disposal, etc. Secondly, you must still pay the rent to the Court, or make suitable escrow arrangements that are acceptable to the judge. If the Court finds that the landlord had notice of the violations, but didn't fix them for over six months, you get your money back and won't owe any rent until repairs are made. This is a good defense to use in conjunction with a rent strike, if building common areas are involved, or enough tenants are affected by the violations.