Definition from Nolo’s Plain-English Law Dictionary
Just, rational, appropriate, ordinary, or usual in the circumstances. It may refer to care, cause, compensation, doubt (in a criminal trial), and a host of other actions or activities. In the law of negligence, for example, the reasonable person standard is the standard of care that a reasonably prudent person would observe under a given set of circumstances. An individual who subscribes to such standards can avoid liability for negligence.