Half-proof
Half-proof (semiplena probatio) is a medieval Roman law idea about evidence. It sits between suspicion and full proof (plena probatio) needed to convict someone of a crime. The concept was introduced by the Glossators in the 1190s, with examples like a single witness or private documents.
When there was half-proof against a defendant, he might be allowed to swear an oath of innocence, or he might be sent for torture to get more evidence that could complete the burden of proof.
Sir Matthew Hale, a leading English jurist, described it as evidence that is imperfect on its own but becomes full proof when combined with other evidence, like a bundle of twigs that breaks easily when separate but not when bound together.
The idea never became firmly established in English law. Voltaire claimed that the Parlement of Toulouse used quarter-proofs and eighth-proofs, but there is no solid evidence for this.
In later times, half-proof is mentioned in 19th-century Scots law and in the 1917 Catholic Code of Canon Law.
This page was last edited on 2 February 2026, at 22:01 (CET).