In law, a reasonable person or reasonable man is a hypothetical person whose character and care conduct, under any common set of facts, is decided through reasoning of good practice or policy. It is a legal fiction crafted by the courts and communicated through case law and jury instructions. In some practices, for circumstances arising from an uncommon set of facts, this person represents a composite of a relevant community's judgment as to how a typical member of that community should behave in situations that might pose a threat of harm (through action or inaction) to the public.
The reasonable person is used as a tool to standardize, teach law students, or explain the law to a jury. 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" in patent law. Ancient predecessors of the reasonable person include the bonus pater familias (the good family father) of ancient Rome, the bonus vir (the good man) and spoudaios (the earnest person) in ancient Greece as well as the geru maa (the silent person) in ancient Egypt.