Definition
Lex manifesta (Law Latin: "manifest" or "open law") is a medieval legal term denoting the form of proof or trial conducted by open, physical ordeal — specifically trial by combat (duel) or trial by ordeal. The term describes a mode of proof that was literally visible and public, as opposed to proof by oath or testimony: the outcome was determined by an observable physical act, the result of which was treated as a direct divine judgment.
The term is synonymous with lex apparens ("apparent law") and appears in the same historical context. Its most significant documentary appearance is in Magna Carta (confirmed 9 Hen. III, c. 28), which restricted its use: no bailiff was to subject any person to lex manifesta — that is, to open ordeal or compurgatory oath — on the bailiff's bare accusation alone, without competent witnesses brought forward for that purpose.
Common Confusion
Lex manifesta and lex apparens are used interchangeably in the historical sources and refer to the same institution. Researchers should not read a distinction between them. Black's notes that the word "manifestam" is omitted from certain versions of King John's original charter (chapter 38) and its articles (chapter 28), meaning the phrase does not appear identically across all manuscript versions of Magna Carta — a trap for researchers working from different recensions of that document.
Do not confuse lex manifesta with manifest law in the modern sense (i.e., law that is plain, obvious, or clearly established). The term is entirely historical and procedural; it carries no modern operative legal meaning.
Why It Matters in Research
Lex manifesta is a term of medieval procedural history, not a living legal concept. Researchers will encounter it almost exclusively in three contexts:
1. Magna Carta scholarship. The Burrill excerpt reproduces the Magna Carta clause (c. 28, 9 Hen. III) in Latin and English translation. Because the word "manifestam" appears in some versions of the charter but not others, source comparison is essential. Researchers relying on a single recension of Magna Carta may not find the term even when examining the same provision.
2. History of proof and trial. Lex manifesta belongs to the cluster of pre-common-law modes of proof — ordeal, battle, compurgation — that were abolished or fell into disuse in England following the Fourth Lateran Council (1215), which prohibited clerical participation in ordeals. Researchers tracing the development of jury trial and rational proof systems should map lex manifesta against this broader abolition.
3. Comparative and ecclesiastical legal history. Black's notes the practice was "said to be still discoverable in some parts of Italy" at the time of that dictionary's compilation — a reminder that abolition in England did not mean simultaneous extinction across European legal systems.
Corpus researchers should note that lex manifesta is an entry-point term: it rarely appears in isolation. It anchors a network of related Latin terms (lex apparens, wager of law, trial by battle, compurgation, ordeal) that together describe the pre-rational proof system. Finding one term in a historical source will typically lead to the others nearby.
Historical Dictionary Support
Black's Law Dictionary and Burrill's Law Dictionary are in agreement on the core meaning: lex manifesta denotes trial by duel or ordeal and is synonymous with lex apparens. Both sources anchor the term to Magna Carta, and Burrill provides the fuller Latin and English text of the operative clause.
Neither source provides significant analytical depth beyond the definition and the Magna Carta reference. Black's adds the textual note about manuscript variation (omission of "manifestam") and the observation about Italian survival, but neither dictionary situates the term within the broader abolition of ordeals or the transition to jury trial. Researchers seeking that context must go beyond the dictionary sources to legal history scholarship on the history of proof.
Burrill's entry is the more useful of the two for primary-source research, as it reproduces the Magna Carta provision in extenso and supplies the English translation, giving researchers the exact clause language in both languages.
Jurisdictional Note
Lex manifesta has no jurisdictional variation in the modern sense — it is a defunct institution. Its legal significance is confined to medieval English and Continental legal history. Magna Carta's c. 28 restriction applies as an English constitutional document; parallel provisions or practices in other jurisdictions require independent research in those legal traditions.