Reasonable Person

The reasonable person (historically reasonable man) is one of many tools for explaining the law to a jury. The "reasonable person" is an emergent concept of common law. While there is (loose) consensus in black letter law, there is no universally accepted, technical definition. As a legal fiction, the "reasonable person" is not an average person or a typical person. Instead, the "reasonable person" is 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.

The standard also holds that each person owes a duty to behave as a reasonable person would under the same or similar circumstances. While the specific circumstances of each case will require varying kinds of conduct and degrees of care, the reasonable person standard undergoes no variation itself.

The "reasonable person" construct can be found applied in many areas of the law. The standard performs a crucial role in determining negligence in both criminal law—that is, criminal negligence—and tort law.

The standard also has a presence in contract law, though its use there is substantially different. It is used to determine contractual intent, or if a breach of the standard of care has occurred, provided a duty of care can be proven. The intent of a party can be determined by examining the understanding of a reasonable person, after consideration is given to all relevant circumstances of the case including the negotiations, any practices which the parties have established between themselves, usages and any subsequent conduct of the parties.

The standard does not exist independently of other circumstances within a case that could affect an individual's judgment.