Definition
Legitimatio (Latin) is the legal process by which a child born outside of marriage — and therefore classified as illegitimate under the law — is given the full legal status of a legitimate child. The effect of legitimation is to confer upon the child the same rights, privileges, and legal standing as a child born in lawful wedlock, including rights of inheritance, succession, and family membership.
The term is drawn directly from Roman civil law and persists in legal writing as the Latin form of the English "legitimation." In historical legal usage, legitimatio described the formal act by which a father acknowledged and elevated the status of his natural child, transforming the child's civil condition by operation of law or sovereign act.
Common Confusion
LEGITIMATIO vs. LEGITIMACY vs. LEGITIMATION: These three terms are closely related but not interchangeable. Legitimacy is a status — the condition of being born to parents lawfully married at the time of birth. Legitimation (or legitimatio) is a process — the act of conferring that status upon a child who did not acquire it at birth. A child may lack legitimacy at birth and acquire it through legitimation. Confusing the status with the process leads to misreading historical sources, particularly in Roman law texts and early common law materials where legitimatio refers specifically to the remedial act, not the underlying condition.
Recognized Forms
/SUBTYPES
Roman civil law recognized several modes of legitimatio:
1. Legitimatio per subsequens matrimonium — legitimation by subsequent marriage of the parents. This was the most common and widely recognized form: if the natural parents later married, their previously born children were thereby legitimated.
2. Legitimatio per rescriptum principis — legitimation by imperial rescript or sovereign decree. Where subsequent marriage was impossible (for example, because the mother had died or could not marry the father), the emperor could issue a formal decree legitimating the child.
3. Legitimatio per oblationem curiae — legitimation by enrollment of the son in the municipal senate (curia). This form was specific to Roman imperial practice and has no close modern analog.
Why It Matters in Research
Researchers encountering legitimatio in historical legal texts should proceed with awareness of several navigational issues.
First, the term is overwhelmingly a civil law and Roman law term. It appears far more frequently in continental legal sources, canon law materials, and Scots law than in English common law texts. Common law historically took a narrower and more rigid view of legitimacy — the common law rule held that only birth within wedlock conferred legitimate status, and subsequent marriage of the parents did not retroactively legitimate a child. Canon law and civil law, by contrast, broadly embraced legitimatio per subsequens matrimonium. This divergence is the source of the famous conflict between English common law courts and ecclesiastical courts in medieval England, and understanding that divide is essential when researching inheritance disputes in that period.
Second, in jurisdictions influenced by civil law (Louisiana, Quebec, Scotland, and the mixed-law systems of South Africa and Latin America), legitimatio had operative legal force in ways it never did in pure common law jurisdictions. Sources from these jurisdictions will use the term with different practical implications than contemporaneous English sources.
Third, the term appears in ecclesiastical and canon law materials in connection with questions of bastardy, which courts had jurisdiction over legitimacy questions, and the effects of legitimation on inheritance. Researchers working on succession disputes in historical English courts will encounter legitimatio as a contested concept at the boundary between ecclesiastical and common law authority.
Fourth, in modern statutes and cases, the Latin form legitimatio has largely disappeared in favor of the anglicized "legitimation" or statutory phrases such as "acknowledgment of paternity." A researcher tracing the concept across centuries must follow the terminology as it transforms.
Historical Dictionary Support
Burrill's Law Dictionary entry for legitimatio is minimal: "Lat. In the civil law. Spelman." This entry does little more than identify the term as Latin and assign it to the civil law tradition, with a citation to Spelman's Glossarium — a seventeenth-century glossary of legal and historical terms — as the authority. The brevity is itself informative. Burrill's terseness signals that legitimatio was understood by his nineteenth-century American audience primarily as a Roman law and civilian term, not as a living operative concept in American common law practice.
What historical dictionaries broadly omit is the genuine complexity of legitimatio as a site of jurisdictional conflict. The civil law/canon law endorsement of legitimation by subsequent marriage versus the common law's rejection of it was one of the more consequential divergences between the two systems during the medieval and early modern periods. That doctrinal clash, well documented in Bracton and in the records of the Statute of Merton (1235), is not reflected in the spare dictionary tradition for this term.
Jurisdictional Note
The operative effects of legitimatio varied sharply between civil law and common law jurisdictions, and that divergence was never fully resolved in mixed-law systems. Modern American states have largely addressed the subject through paternity acknowledgment statutes and the Uniform Parentage Act rather than through the concept of legitimation as such, making the classical term primarily historical in U.S. research contexts.