Reasonable person

In law, a reasonable person, reasonable man, or the man on the Clapham omnibus is a hypothetical person of legal fiction who is ultimately an anthropomorphic representation of the body care standards crafted by the courts and communicated through case law and jury instructions.

Strictly according to the fiction, it is misconceived for a party to seek evidence from actual people in order to establish how the reasonable man would have acted or what he would have foreseen. This person's character and care conduct under any common set of facts, is decided through reasoning of good practice or policy—or "learned" permitting there is a compelling consensus of public opinion—by high courts.

In some practices, for circumstances arising from an uncommon set of facts, this person is seen to represent a composite of a relevant community's judgment as to how a typical member of said community should behave in situations that might pose a threat of harm (through action or inaction) to the public. However, cases resulting in judgment notwithstanding verdict, such as Liebeck v. McDonald's Restaurants, can be examples where a vetted jury's composite judgment were deemed outside that of the actual fictional reasonable person, and thus overruled.

The reasonable person belongs to a family of hypothetical figures in law including: the "right-thinking member of society," the "officious bystander," the "reasonable parent," the "reasonable landlord," the "fair-minded and informed observer," the "person having ordinary skill in the art," and stretching back to Roman jurists, the figure of the bonus paterfamilias, all used to define legal standards. While there is a loose consensus in black letter law, there is no accepted technical definition. As with legal fiction in general, it is somewhat susceptible to ad hoc manipulation or transformation, and hence the "reasonable person" is an emergent concept of common law. The "reasonable person" is used as a tool to standardize, teach law students, or explain the law to a jury.

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