What is the legal duty of care of a plaintiff in a negligence action?

An essential element of any negligence claim is a legal duty of care. Duty is a question of law to be determined by the court on a case-by-case basis. "As a general rule, one owes no duty to control the conduct of another, nor to warn those endangered by such conduct. Such a duty may arise, however, if '(a) a special relation exists between the actor and the third person which imposes a duty upon the actor to control the third person's conduct, or (b) a special relation exists between the actor and the other which gives the other a right to protection.' [Citations.]" (Davidson v. City of Westminster (1982) 32 Cal.3d 197, 203, 185 Cal.Rptr. 252, 649 P.2d 894.)