Definition
A Latin term from the civil law tradition meaning proof. In its broadest sense, probatio denotes the act or means of establishing the truth of a matter before a legal tribunal. The historical dictionaries emphasize that probatio referred specifically to direct proof, as distinguished from indirect or circumstantial evidence, though the term also served as a general label for the evidentiary function itself.
Three recognized compound forms carry distinct technical meanings:
1. Probatio viva ("living proof"): Proof given by witnesses testifying orally, voce viva. The testimony of a live witness delivered in open proceeding.
2. Probatio mortua ("dead proof"): Proof by inanimate objects — deeds, writings, instruments, and other documentary evidence. The term signals that the evidence cannot be cross-examined or respond; it speaks only through its text.
3. Probatio plena ("full proof"): In civil law procedure, proof sufficient to establish a fact conclusively. Historically defined as proof by two witnesses or by a public instrument. Distinguished from probatio semiplena (half-proof), which was partial or incomplete proof insufficient on its own to establish a fact.
Common Confusion
Researchers may conflate probatio with the English terms "probation" and "probate," both of which derive from the same Latin root probare (to prove or test). Probation in modern criminal law refers to a supervised release sentence. Probate refers to the process of proving and administering a will. Neither carries the evidentiary meaning of probatio as it appears in civil law sources and historical legal texts. Seeing probatio in a Latin maxim or civilian treatise should signal evidentiary doctrine, not sentencing or succession procedure.
Recognized Forms
/SUBTYPES
Probatio viva — oral, witness-based proof
Probatio mortua — documentary or written proof
Probatio plena — full proof meeting the civil law threshold for conclusive establishment of fact
Probatio semiplena — half-proof; partial evidence requiring supplementation (referenced in civil law sources though underrepresented in the dictionary entries surveyed)
Why It Matters in Research
Probatio surfaces almost exclusively in three research contexts: (1) Latin maxims reproduced in common law treatises, particularly those borrowing from civilian sources; (2) ecclesiastical and admiralty court records, where civil law procedure governed; and (3) historical evidence scholarship tracing the development of proof standards before modern rules of evidence solidified.
The viva/mortua distinction matters for tracing the common law's early treatment of documentary evidence. Bracton's use of these terms (cited in Burrill) places the distinction in 13th-century English legal thought, showing that even early common law borrowed civilian vocabulary to categorize proof types. Researchers working in pre-modern English legal records may encounter this framing and should not assume it maps directly onto modern concepts of direct versus documentary evidence.
The probatio plena standard — proof by two witnesses or a public instrument — is foundational for understanding why the two-witness rule appeared in contexts ranging from treason statutes to testamentary execution requirements. A researcher tracing the historical basis for witness-number requirements in English or American law will frequently encounter probatio plena as the civilian antecedent.
The maxim embedded in Burrill — Ei incumbit probatio qui dicit, non qui negat (the burden of proof lies upon the one who affirms, not the one who denies) — is among the most frequently cited civilian maxims in common law burden-of-proof discussions. Identifying probatio in this maxim context is essential for researchers working on the intellectual history of burden of proof.
Historical Dictionary Support
The sources converge on core meaning — probatio equals proof, with particular reference to direct rather than circumstantial evidence — but vary considerably in depth. Burrill is the most useful source here by a wide margin. It supplies the Bracton citation for probatio viva and mortua, connects the term to Digest 22.3.2, and reproduces the evidentiary maxim on burden of proof. Black's 2nd edition adds probatio plena with a reference to Hallifax's Civil Law, providing the two-witness standard. The 1st edition of Black's and Rapalje & Lawrence offer only the spare definitional core without the compound forms. Anderson directs readers to PROBARE without providing independent content, which is unhelpful for researchers who encounter probatio in source texts.
What the historical dictionaries collectively miss: they do not adequately treat probatio semiplena or the procedural consequences that flowed from the plena/semiplena distinction in civilian courts. Researchers working in ecclesiastical jurisdiction or admiralty who encounter evidence questions calibrated to degree of proof will need to consult civilian treatises — Ayliffe's Parergon, Domat's Civil Law, or Hallifax directly — rather than relying on these dictionary entries alone.
The maxim Probationes debent esse evidentes, perspicuae et faciles intelligi (proofs ought to be clear, evident, and easy to understand) preserved in Burrill reflects a civilian principle of evidentiary sufficiency that has analogs in modern authentication and sufficiency doctrine, though the direct line of influence is contested.
Jurisdictional Note
Probatio as a term of art belongs to civil law procedure and appears in American and English legal sources primarily through the channels of admiralty, ecclesiastical, and equity jurisdiction. It does not function as an operative term in modern common law evidence doctrine, but it remains relevant to historical research across any jurisdiction that maintained civilian-influenced courts.