Adverse possession is a legal concept that allows a trespasser, whether a stranger or a neighbor, to gain legal title over land. This guide will help you understand everything you need to know about the state of New York squatters' rights and adverse possession laws.Vacant possession only means they have to be out at the point of completion. The contract won't go through if they aren't out. Discover the ultimate guide to selling your vacant house on Long Island, featuring expert tips, strategies, and local insights for a successful sale. This solution is usually only possible when the real property in question is a vacant and unimproved lot. 68 votes, 70 comments. However, we should not be stating "out of possession. Vacant possession is an element of property law that ensures a property is left in good condition when it changes hands. When a property is being sold, as the general conditions of sale state that a buyer is entitled to vacant possession on completion.