In New York City and State, property owners (including municipalities) are responsible for keeping the property free of dangerous or hazardous conditions. There is the exception that the owner knew or should reasonably have known about those conditions.
The unsafe conditions can be obvious — such as slippery steps — or less obvious, such as a pothole or uneven sidewalk. The dangerous condition could be permanent — a broken sidewalk, for instance — or as temporary as a spill in a supermarket aisle.
If the owner can be proven to have known about the hazard or caused it– or if the hazard is permanent in nature — that owner can be held liable for the personal injury that results. For temporary hazards, liability can depend on how long the hazard was in place and on whether or not it was evident to the property owner or was caused by them.