Ei incumbit probatio qui dicit

The presumption of innocence, sometimes referred to by the Latin expression ei incumbit probatio qui dicit, non qui negat (the burden of proof is on the one who declares, not on one who denies), is the principle that one is considered innocent unless proven guilty.

In many states, presumption of innocence is a legal right of the accused in a criminal trial, and it is an international human right under the UN's Universal Declaration of Human Rights, Article 11. Under the presumption of innocence, the legal burden of proof is thus on the prosecution, which must collect and present compelling evidence to the trier of fact. The trier of fact (a judge or a jury) is thus restrained and ordered by law to consider only actual evidence and testimony presented in court. The prosecution must, in most cases prove that the accused is guilty beyond reasonable doubt. If reasonable doubt remains, the accused must be acquitted.

Under the Justinian Codes and English common law, the accused is presumed innocent in criminal proceedings, and in civil proceedings (like breach of contract) both sides must issue proof.

The sixth century Digest of Justinian (22.3.2) provides, as a general rule of evidence: Ei incumbit probatio qui dicit, non qui negat—"Proof lies on him who asserts, not on him who denies". It is there attributed to the second and third century jurist Paul. It was introduced in Roman criminal law by emperor Antoninus Pius.

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