A legal fiction is a fact assumed or created by courts which is then used in order to apply a legal rule. Legal fiction allows an intellectual tradition of defining a legal standard such as by way of a person, which has resulted in the creation of classic hypothetical figures in law including: The man on the Clapham omnibus, the  right-thinking member of society, the officious bystander, the "reasonable parent," the "reasonable landlord," and the "fair-minded and informed observer," and stretching back to Roman jurists, the figure of the bonus paterfamilias. Legal fictions are mostly encountered under common law systems.