Definition
Comparatio literarum (Latin: "comparison of writings") is a civil law term for the evidentiary method of proving the authenticity or authorship of a document by comparing it against other writings of known or admitted genuineness. It functioned as a formal mode of proof within civil law systems, allowing tribunals to determine whether a disputed writing shared characteristics with authenticated exemplars, thereby establishing or defeating a document's validity.
The concept is the historical antecedent to what common law jurisdictions now call handwriting comparison or comparison of handwriting, and it appears in the Corpus Juris Civilis as a recognized, if limited, evidentiary mechanism.
Common Confusion
Comparatio literarum should not be conflated with collatio signorum, a related but distinct civil law concept. Collatio signorum referred to the comparison of seals or marks, while comparatio literarum addressed written text and handwriting specifically. Burrill's dictionary explicitly cross-references both terms, and researchers who encounter either phrase in historical sources should confirm which mode of proof is being invoked before treating them as interchangeable. In some civilian treatises the two are discussed together in proximity, which compounds the risk of confusion.
Why It Matters in Research
This term is a navigational marker for two distinct research paths: the history of evidence law in civil law systems, and the pre-modern foundations of handwriting authentication as a legal doctrine.
Researchers working in historical sources—particularly Scottish, French, or Continental legal materials from the sixteenth through nineteenth centuries—will encounter comparatio literarum in discussions of documentary proof where common law researchers would instead expect to find references to attesting witnesses or the best evidence rule. Alison's Criminal Practice (cited by Burrill) situates the concept in Scottish criminal procedure, which blended civilian and common law influences. Researchers using that source should be alert to the fact that Scottish treatment of handwriting comparison drew on civilian theory even as English common law was developing its own parallel doctrine skeptically and more restrictively.
The phrase appears rarely in purely English common law materials. When it does appear, it is almost always in comparative or treatise-style discussions, not in case analysis. Searching for this term in common law reports will yield sparse results; the productive corpus is treatises, Scottish authorities, and civilians writing on the law of proof.
The term also signals a period boundary. Modern handwriting comparison law—including the admissibility of expert testimony on questioned documents—evolved away from the civilian comparatio framework and is now governed in most jurisdictions by evidentiary rules that do not invoke this terminology at all. A researcher tracing the intellectual lineage of questioned document examination will find comparatio literarum a useful early waypoint, but must then shift to different vocabulary as the doctrine matures through the nineteenth and twentieth centuries.
One research trap: Rapalje & Lawrence truncate their entry with a cross-reference ("See COMPARISON OF HAND-"), suggesting the practical content was consolidated under the anglicized entry. Researchers relying solely on Rapalje & Lawrence for this concept should follow that cross-reference rather than treating the Latin entry as self-contained.
Historical Dictionary Support
The three source dictionaries are in agreement on the core definition—comparison of writings as a civil law mode of proof—but they differ meaningfully in depth and utility.
Black's entry is bare: it provides the translation and the characterization as a recognized mode of proof, nothing more. It offers no citations and no guidance on scope or limitation.
Rapalje & Lawrence are even thinner, providing only a fragment and a redirect. Their entry is useful primarily as evidence that by the late nineteenth century, American legal lexicography had largely absorbed this concept under English-language headings, treating the Latin phrase as secondary vocabulary.
Burrill is the most substantive of the three. He supplies citations to the Codex (Cod. 4. 21. 20) and the Novels (Nov. 49, c. 2), grounding the term in its primary sources. He also cites Bell's Dictionary, Bell's Contract of Sale, and Alison's Criminal Practice—a cluster of Scottish authorities that reflects the term's continued relevance in mixed civil-common law jurisdictions well into the nineteenth century. Burrill's entry is the one to begin with for any serious historical investigation.
None of the three sources discusses the limitations placed on this mode of proof in civilian systems—the fact that it was not universally admitted and required conditions for its use—a gap that researchers should fill by consulting the underlying Corpus Juris Civilis provisions Burrill cites.
Encyclopedia Cross-Reference
See Law Mind Encyclopedia: Comparison of Handwriting; History of Documentary Evidence