Definition
Constitutio (Latin) is a term of Roman and civil law origin carrying three distinct meanings, each important to different research contexts.
1. Imperial ordinance (civil law, primary meaning). In Roman and civil law, a constitutio was an imperial enactment deriving its legal force from the sole will of the emperor, as distinct from a lex (legislation enacted through popular or senatorial process), a senatus-consultum (decree of the Senate), or other recognized forms of Roman law. The maxim underlying its authority was quod principi placuit legis habet vigorem — "what has pleased the prince has the force of law." Imperial constitutiones took several procedural forms, including rescripts (epistolae), judicial decrees (decreta), and edicts (edicta), all of which were treated as binding law.
2. Settlement or establishment (civil law, secondary meaning). In civil procedure usage, constitutio could also refer to an establishment or settlement — specifically, a controversy resolved between the parties without proceeding to formal trial. In this sense it functions as a precursor concept to what modern law calls settlement or compromise.
3. Ordinance or statute (old English law). In the context of medieval English law, constitutio was used to denote an ordinance or statute, or a specific provision within a statute. This usage reflects the absorption of Latin legal vocabulary into the English legislative tradition, particularly in royal and ecclesiastical instruments.
A fourth, derivative meaning — a sum paid according to agreement — appears in Du Cange's glossary and reflects the contractual dimension of the term in medieval usage, though this sense is rarely encountered in English legal sources.
Common Confusion
Researchers should not conflate constitutio with constitution in the modern Anglo-American sense. A modern constitution is a foundational document establishing the structure of government and limiting sovereign power — a concept that inverts the logic of the Roman constitutio, which expressed the unlimited will of the emperor. The two terms share etymological roots but represent opposite theories of legal authority. Encountering constitutio in a civil law treatise, a Digest gloss, or a medieval English statute does not import modern constitutional doctrine.
Recognized Forms
/SUBTYPES
The Roman constitutio appeared in several recognized procedural forms:
— Edicta: general pronouncements issued to the public at large, binding throughout the empire.
— Decreta: decisions rendered by the emperor in his judicial capacity, resolving specific disputes.
— Rescripta (Epistolae): written responses to petitions from officials or private parties, providing authoritative rulings on legal questions.
— Mandata: administrative instructions issued to officials, particularly provincial governors.
These forms are discussed in Justinian's Institutes and the Digest, and understanding which form is at issue matters when interpreting the scope and precedential weight of a cited constitutio.
Why It Matters in Research
The term appears in three distinct research streams, and conflating them causes real interpretive errors.
In Roman law and civil law sources, constitutio is a technical term of art tied to a specific theory of imperial sovereignty. When reading the Digest, the Institutes, or later civil law commentators (Accursius, Bartolus, later the Civilians), the term carries its technical valence. Burrill's dictionary preserves the Digest citation (Dig. 1.4.1) and the key maxim, making it a reliable reference point for tracing the concept's foundational authority.
In medieval English sources, constitutio appears in royal ordinances, conciliar acts, and ecclesiastical instruments — particularly in contexts where Latin was the drafting language. The Constitutions of Clarendon (1164) and the Constitutions of Oxford (1258) use the term in this statutory/ordinance sense. Researchers working in this period must read constitutio as meaning ordinance or statutory provision, not Roman imperial edict.
In early modern legal treatises that synthesize civil law and common law materials — particularly works in the natural law tradition — constitutio may slide between the imperial and statutory meanings without explicit signal. Checking whether the author is operating in a civilian or common law register is essential before interpreting the term.
The secondary meaning (settlement of controversy without trial) is easily overlooked and appears primarily in civilian procedural texts. Bouvier flags it with the Calvin citation; it does not appear prominently in common law sources.
Researchers using Law Mind sources should note that the historical dictionaries do not always cleanly distinguish among the three primary meanings. Burrill is the most technically precise on the civil law sense. Black's (both editions) and Bouvier compile meanings without strongly differentiating their respective legal contexts. Rapalje & Lawrence offer the clearest separation of old English from civil law usage and are most useful when jurisdictional context needs to be anchored quickly.
Historical Dictionary Support
The historical dictionaries converge on the civil law definition as primary and are consistent in attributing its force to the imperial will, citing the Digest (1.4.1) and the maxim quod principi placuit. Burrill provides the most expansive treatment, quoting the Latin sources directly and linking the constitutio to its formal subtypes — a feature absent from the other sources. Black's (both editions) and Bouvier present substantially similar entries without the subtype analysis. Rapalje & Lawrence is the most compressed and practically organized, distinguishing old English from civil law usage in numbered definitions.
None of the historical sources adequately flags the risk of confusion with the modern constitutional meaning — a gap that is significant for researchers trained in Anglo-American public law approaching Roman or medieval materials for the first time. The Du Cange meaning (sum paid by agreement) is noted by Black's and Bouvier but not elaborated; it is a marginal gloss more useful to medieval historians than to legal doctrine researchers.
Jurisdictional Note
Constitutio as a legal term is most relevant in jurisdictions with civil law foundations (Louisiana, Quebec, and jurisdictions deriving from Roman-Dutch or Spanish law) and in historical English materials predating the consolidation of common law vocabulary. In modern common law jurisdictions, the term appears primarily in academic, historical, or comparative law contexts rather than in operative legal instruments.