Instead, the tort of negligence makes the defendant liable for failing to act reasonably. Duty of care: the responsibility owed to avoid carelessness that causes harm to others. A defendant owes a duty of care to anyone who might be reasonably affected by the defendant"s conduct. If there is a similar precedent case, we will use that case to decide if there duty of care owed. If the case at issue is novel, then the court is required to assess of duty in the following way: Is there a prima facie (at first sight or on first appearances) duty of care? a. Reasonable foreseeability considers whether the defendant should objectively have anticipated that his or her act or omission would cause harm to the plaintiff. If the answer to this question of reasonable foreseeability is yes, proceed to the next question. b.