Latin for the logical element of the law or reason for the law. It may also denote the purpose of a legal rule or a policy reason or underlying purpose for a specific norm, rule, provision, act of legislation, court ruling, etc. For a statute or articles enacted by a private or public authority, it is the main purpose of the articles, etc.

A law can be purposefully interpreted (purposive interpretation) mainly in doubtful cases, where an interpretation under normal situations (ordinary or technical meaning of the terms of a  law or rule) bears no convincing value, and where legal arguments are not enough to eliminate interpretive doubts.