Definition
Citatio (Latin/Law Latin) is the formal process by which a court summons a party to appear and answer before it. In classical civil law and its derived systems, citatio is the foundational act of judicial notification — the mechanism by which the court's authority is extended to a person who must participate in proceedings. It is, in essence, the original form of what modern practice calls a summons or citation.
The term operates across several historical legal systems and carries slightly different procedural weight in each context:
1. Civil law. In the Roman and continental civil law tradition, citatio was the formal summons issued to bring a defendant before the tribunal. The maxim citatio est de jure naturali — citation is of natural law — reflects the doctrine that no person may be condemned without first being called to answer. This principle is foundational: process cannot begin in earnest until citatio has properly issued and been served.
2. English ecclesiastical, probate, and divorce practice. In courts of ecclesiastical jurisdiction, and in the probate and divorce courts that inherited much of their procedural law from canon and civil law, citatio was the standard form of originating process, replacing the common law writ of summons. The defendant or respondent was called before the court by citation rather than by writ.
3. Scots law. In Scottish practice, citatio referred to the calling of a party to an action by a court officer acting under a proper warrant. It encompassed both the act of summoning and the service of the writ or bill of summons.
Recognized Forms
/SUBTYPES
Citatio ad reassumendam causam — A summons to "take up the cause again." This specialized form of citatio issued when one of the parties to a pending suit died before its determination. The surviving or successor party used it to revive the action: a plaintiff could issue it against the deceased defendant's heir, or a defendant could invoke it against the deceased plaintiff's heir. It is the civil law analogue to the common law bill of revivor, the procedural device used to continue an action interrupted by death.
Why It Matters in Research
Researchers working in pre-modern English legal records — particularly ecclesiastical court records, admiralty proceedings, probate files, and early divorce proceedings — will encounter citatio as the operative originating process rather than any common law writ. Failure to recognize citatio as the functional equivalent of a summons can cause researchers to misread procedural posture, particularly in determining when jurisdiction was properly invoked or whether a proceeding was valid.
The maxim citatio est de jure naturali is a live doctrinal point in sources dealing with due process and natural justice. When historical treatises invoke this principle, they are asserting not merely a procedural rule but a claim about the moral foundations of judicial authority — that notice and the opportunity to be heard are requirements of natural law, not merely positive enactment. Researchers tracing the intellectual lineage of modern due process or natural justice doctrine should flag every appearance of this maxim.
The citatio ad reassumendam causam is easy to overlook in case file research. When a file contains what appears to be a mid-suit summons rather than an originating writ, and one of the parties has recently died, this subtype is the likely explanation. Researchers should look for it as a signal of party substitution or abatement followed by revival.
In Scots law materials, citatio is more broadly used than in English sources and can appear in contexts that would use different terminology south of the border. Scottish institutional writers treat citatio as encompassing the entire process of judicial intimation, not merely the document itself.
Historical Dictionary Support
The three source dictionaries agree closely on the core definition: citatio is a summons or citation to court, derived from the Latin citare (to summon). Burrill is the most historically precise of the three, citing Skene's De Verborum Significatione and a rule from 12 Co. 44 — the principle that citations should not be granted before the ground for citation is expressed. This requirement of specificity in the originating process is a meaningful procedural constraint that Black's editions do not foreground.
Black's Second Edition adds the most doctrinal content, particularly the citatio ad reassumendam causam subtype and the natural law maxim. The entry in Black's First Edition is the briefest, noting ecclesiastical, probate, and divorce court usage and the Scots practice, with a cross-reference to Blackstone and Stephen's Commentaries.
None of the historical dictionaries fully develops the relationship between citatio and modern due process doctrine, though the natural law maxim — citatio est de jure naturali — points directly toward it. Researchers should not treat these dictionary entries as exhaustive on the constitutional implications; they are procedural descriptions, not jurisprudential analyses.
Jurisdictional Note
Citatio as a term of art is most likely to appear in English ecclesiastical court records, admiralty records, Scottish legal materials, and sources rooted in the civil law tradition. Common law courts of record used writs of summons rather than citations as originating process; encountering citatio in a common law file is unusual and may indicate either a civil law-influenced court or a specialized procedural posture.
Encyclopedia Cross-Reference
See Law Mind Encyclopedia: Summons; Due Process and Natural Justice; Ecclesiastical Courts; Bill of Revivor.