N.Y. Real Prop. Acts. Law § 227-e

§ 227-e. Landlord duty to mitigate damages. In any lease or rental\nagreement, excluding any real estate purchase contract defined in\nparagraphs (a), (c) and (d) of subdivision four of section four hundred\nsixty-one of this chapter, covering premises occupied for dwelling\npurposes, if a tenant vacates a premises in violation of the terms of\nthe lease, the landlord shall, in good faith and according to the\nlandlord's resources and abilities, take reasonable and customary\nactions to rent the premises at fair market value or at the rate agreed\nto during the term of the tenancy, whichever is lower. If the landlord\nrents the premises at fair market value or at the rate agreed to during\nthe term of the tenancy, the new tenant's lease shall, once in effect,\nterminate the previous tenant's lease and mitigate damages otherwise\nrecoverable against the previous tenant because of such tenant's\nvacating the premises. The burden of proof shall be on the party seeking\nto recover damages. Any provision in a lease that exempts a landlord's\nduty to mitigate damages under this section shall be void as contrary to\npublic policy.\n