Definition
To clear oneself of a criminal charge through a sworn oath. In medieval legal practice, a person accused of a crime could adlegiare — that is, formally deny the charge under oath, often supported by the oaths of compurgators (oath-helpers), as a recognized method of establishing innocence. The act was a procedural mechanism of proof rather than a factual defense: the oath itself, properly administered and supported, functioned as the legal vindication.
Common Confusion
ADLEGIARE is closely associated with compurgation and wager of law, and the three concepts are easily conflated. Adlegiare names the act of oath-clearing by the accused. Compurgation names the broader system in which oath-helpers swear to the accused's credibility. Wager of law is the common law procedural form of compurgation, most associated with debt actions. Researchers should treat adlegiare as the Latin root term for the act, and compurgation/wager of law as the developed procedural institutions built around it.
Why It Matters in Research
This is an archival and historical term with no modern operational legal meaning. Researchers will encounter it primarily in:
— Medieval and early modern legal records, ecclesiastical court materials, and treatises predating the abolition of compurgation in England (formally abolished in 1833 by 3 & 4 Will. IV, c. 42).
— Comparative or historical scholarship on proof systems, where adlegiare is contrasted with trial by ordeal, trial by battle, and eventually jury trial.
— Canon law sources, where oath-purgation survived longer in ecclesiastical proceedings than in common law courts.
The key navigational trap is anachronism: researchers reading medieval plea rolls or ecclesiastical records must recognize that adlegiare describes a legitimate, formal legal procedure — not an evasion or irregularity. Evaluating such records through modern evidentiary assumptions will produce misreadings.
The term also surfaces in secondary literature on the transition from early medieval proof systems to rationalized evidence law. Connections run directly to scholarship on ordeals, canonical purgation, and the rise of the jury. A researcher following this thread will move quickly from adlegiare into compurgation, then into wager of law, and eventually into the history of the jury itself — one of the major evolutionary arcs in Anglo-American legal history.
Historical Dictionary Support
Both Black's Law Dictionary editions consulted offer an identical, minimal entry: "To purge one's self of a crime by oath." The definition is accurate as far as it goes but provides no procedural context — no mention of compurgators, no indication of which courts employed the mechanism, and no note of the term's obsolescence. Researchers relying solely on Black's will understand the core act but will lack the institutional framework needed to interpret historical sources intelligently.
The historical dictionaries are in full agreement on the core meaning, which is unsurprising given the term's specificity and its lack of contested application. What the sources miss is the distinction between lay compurgation (common law wager of law) and canonical purgation (ecclesiastical courts), which operated under different rules and survived to different dates. Neither edition flags the term as obsolete or situates it in the history of proof.
Jurisdictional Note
Adlegiare and the underlying practice of compurgation were common to both common law and canon law traditions but diverged significantly in their development. English common law courts largely confined compurgation to debt and detinue actions; ecclesiastical courts used canonical purgation more broadly. The practice disappeared earlier in common law courts and was formally abolished by statute in England in 1833. It has no equivalent procedural role in modern common law jurisdictions.