Onus Probandi

burden of proof, responsibility to present proof

For Burden of Proof use in Rhetoric see: Burden of proof (rhetoric)In the common law, burden of proof is the obligation to prove allegations which are presented in a legal action. More colloquially, burden of proof refers to an obligation in a particular context to defend a position against a prima facie other position.
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The burden of the proof.

It is a general rule that the party who alleges the affirmative of any proposition shall prove it. It is also a general rule that the onus probandi lies. upon the party who seeks to support his case by a particular fact of which he is supposed to be cognizant; for example, when to a plea of infancy, the plaintiff replies a promise after the defendant had attained his age, it is sufficient for the plaintiff to prove the promise and it lies on the defendant to show that he was not of age at the time. But where the negative involves a criminal omission by the party, and consequently where the law, by virtue of the general principle presumes his innocence, the affirmative of the fact is also presumed.

In general, wherever the law presumes the affirmative, it lies on the party who denies the fact, to prove the negative; as, when the law raises a presumption as to the continuance of life; the legitimacy of children born in wedlock; or the satisfaction of a debt.

The party on whom the onus probandi lies is entitled to begin, notwithstanding the technical form of the proceedings.
   

This entry contains material from Bouvier's Legal Dictionary, a work published in the 1850's.

The burden of proof