In Court of Session practice, signetting is the administrative step by which the court applies the signet (seal) to a writ—most commonly a summons—formally issuing it and authorising service on the defender. In practical terms, a signetted summons is the version that may lawfully be served; without signetting, service is incompetent and the action cannot proceed.
Signetting is a Scots law term used in the Court of Session. It is governed by the Rules of the Court of Session and Acts of Sederunt rather than defined in primary legislation. Once signetted, the pursuer can arrange service (typically by a messenger-at-arms), and procedural time limits under the Rules begin to run, including the period within which service must be effected and deadlines for any notice of intention to defend.
Not all Court of Session processes use signetting: certain petition procedures proceed on a judicial warrant to cite or intimate instead. There is no direct equivalent in England & Wales, Northern Ireland or Ireland; the closest concepts are court “issue” or “sealing” of a claim form or originating summons to authorise service.