Premises liability is a general concept that involves what level of responsibility landowners must exercise to maintain safe premises for other people.
Sometimes a landowner may argue that they were unaware of the unsafe condition of their property. The question which will determine if the owner is liable for some wrongdoing is whether the owner had either actual or constructive notice of the hazardous conditions.
Actual notice is when the landowner actually knew of an alleged defect. Constructive notice is when someone may not have actually known of the hazard, but they should have known of the hazard because of the length of time that it was there, or it was plainly visible and it is expected that the landlord could have remedied the defect in time had due diligence and reasonable care been exercised.
Ultimately, factors such as how apparent something is and how long the defect was on the premises will determine what level of notice the owner had, or should have had, in any instance.