Property owners are legally responsible for injuries occurring as the result of dangerous or hazardous conditions on their property only when the property owner knew of the condition, or through the exercise of due care should have known of the condition.

The hazard may be obvious (such as a broken stair or darkened stairway) or hidden (such as a hole in the ground partially or completely covered by grass). The hazard may not be apparent (as in flooring which appears normal but is slippery or rotting). It could be permanent (such as a change in elevation) or temporary (such as a liquid spill in a supermarket aisle).

If the hazard is permanent in nature, the owner may generally, but not always, be held to have at lease constructive knowledge of its existence. The same is true of even a temporary hazard created by the owner or by an agent or employee of the owner.

If the condition is temporary (like a liquid spill), the length of time the condition existed before the fall occurred may be significant, since the owner must have a reasonable period of time in which to discover the hazard and remove it. If the spill occurred just seconds before the slip and fall, then there may be no legal liability. However, if the victim can show that the spill had been present for some time (such as where the liquid became dirty or discolored), then it maybe assumed that the owner had reasonable time in which to discover and remove the hazard, even though the owner did not have actual knowledge of its existence.
Recovery of damages may not be possible in cases where the hazard is open and obvious. The law requires everyone to watch where he or she is going and the failure to keep a reasonable lookout may constitute contributory negligence, barring the claim. However, where the owner has, through its actions, distracted one from looking, then the failure to see the hazard may not bar the claim. This may especially be true in retail sales establishments where goods are attractively displayed for maximum effect.