Livingston v. Kiersted
10 Johns. 362
N.Y. Sup. Ct.1813Check TreatmentThe exclusion of testimony to prove that a witness offered on the part of the plaintiffs was non. co7npos, by reason of his mental derangement, was erroneous. If it could have been shown to the court below that the witness was deranged, or had not the ordinary understanding, he must have been excluded as incompetent. Idiots, lunatics and mad7iien are not competent witnesses, and this must be shown to the court by proof, like any other charge of incompetency. The defendant was prevented, from showing this, and the witness was admitted. As we cannot tell what weight the jury may have given to his testimony, the judgment must, for that cause, and without considering the other points raised, be reversed.
.Judgment reversed»