Morrison v. California (1934) 291 U.S. 82, stands for the proposition that where the evidence is in equipoise "the promotion of convenience from the point of view of the prosecution will be outweighed by the probability of injustice to the accused." (Id. at p. 94.) As Justice Cardozo explained, "the decisions are manifold that within limits of reason and fairness the burden of proof may be lifted from the state in criminal prosecutions and cast on a defendant. The limits are in substance these, that the state shall have proved enough to make it just for the defendant to be required to repel what has been proved with excuse or explanation, or at least that upon a balancing of convenience or of the opportunities for knowledge the shifting of the burden will be found to be an aid to the accuser without subjecting the accused to hardship or oppression." (Id. at pp. 88-89.)