What is the standard of care an alleged tort feasor must exercise to avoid liability?

The standard of care an alleged tort feasor must exercise to avoid liability is summarized in Regina v. Victoria (City) 1999 CanLII 706 (SCC), 1999, 1 S.C.R., 201, at para. 28: … To avoid liability, a person must exercise the standard of care that would be expected of an ordinary, reasonable, and prudent person in the same circumstances. The measure of what is reasonable depends on the facts of each case, including the likelihood of a known or foreseeable harm, the gravity of the harm and the burden or cost which would be incurred to prevent the injury. In addition, one may look to external indicators of reasonable conduct, such as custom, industry practice, and statutory or regulatory standards.