Ei incumbit probatio qui dicit
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Ei incumbit probatio qui dicit, non qui negat. The burden of the proof lies upon him who affirms, not he who denies. Dig. 22, 3, 2; Tait on Ev. 1; 1 Phil. Ev. 194; 1 Greenl. Ev. Sec. 74; 3 Louis. R. 83; 2 Dan. Pr. 408; 4 Bouv Inst. n. 4411.
A Law Dictionary, Adapted to the Constitution and Laws of the United States. By John Bouvier. Published 1856.