What common law principles apply to occupiers' liability?

Saskatchewan has no occupiers' liability legislation, therefore common law principles apply. In cases such as this, the duty of care which the owner or occupier of land has to a customer is based on the inviter/invitee standard. The duty owed to such a person was stated by Willes, J., in Indermaur v. Dames (1866), L.R. 1 C.P. 274, at p. 288: "And, with respect to such a visitor at least, we consider it settled law, that he, using reasonable care on his part for his own safety, is entitled to expect that the occupier shall on his part use reasonable care to prevent damage from unusual danger, which he knows or ought to know ..."