Constantine I

Roman emperor (r. 306–337 AD) whose AD 334 constitution — preserved in the Codex Justinianus as CJ 4.20.9 — is the legal-historical origin point of unus testis, nullus testis ("one witness, no witness"): the rule that a single, uncorroborated witness cannot establish a fact regardless of plausibility. Matters to this vault as the foundational figure the entire corroboration-doctrine cluster traces back to, measured against by every later leg of the lineage — medieval half-proof grading, French ancien-régime procedure, US patent law, modern meta-analysis — that moc-one-witness-is-not-enough gathers.

References

• claim-unus-testis-nullus-testis-roman-canon-law-lone-witness-rule

Updates

• 2026-10-22: a bridge-check comparing the vault's own independent_roots field against the medieval système de preuve légale found that the historical system most readers (and an earlier vault note) reach for the flat unus testis, nullus testis image to describe was itself graduated — half-proofs could sum to full proof except at named chokepoints — narrowing, not confirming, the "two-witness bar" reading of this doctrine. (observation-independent-roots-and-preuve-legale-are-graduated-bookkeeping-not-flat-bars)