Opinion by
Mr. Chibe Justice Fell,
*405When the prisoner was called to the bar of the court to plead to the indictment charging him with the crime of murder, his counsel presented a petition, signed by them in his behalf, in which it was alleged that he was then insane and not mentally competent to confer with his counsel or to comprehend the nature of the proceedings on a trial of the indictment, and it was asked that an issue be framed to try the question of his sanity, as provided by section 67 of the Act of March 31, 1860, P. L. 427. The petition was granted by the court, an issue was framed and the jury found the prisoner was sane. On the trial of this preliminary issue the jury were instructed that in order to find the appellant insane they must be satisfied of his insanity beyond a reasonable doubt. This instruction was incorrect. Sanity is the normal condition of mind and its existence is presumed. But in order to overcome the presumption of sanity it is not necessary that insanity should be established beyond a reasonable doubt. That this measure of proof is not required when insanity is set up as a substantive defense on the trial of the main issue has been held in a long line of our cases which are reviewed by our Brother Brown in Com. v. Molten, 230 Pa. 399, and reaffirmed by the decision in that and in subsequent cases. The same rule obtains on the trial of a preliminary issue to determine whether a prisoner, who is called to plead, is then insane. The question to be decided is whether he is mentally able to make a rational defense and this fact is to be decided by a preponderance of the evidence.
The error in the trial of the preliminary issue rendered all subsequent proceedings of which it was a part invalid. It was not afterwards cured by the withdrawal of the plea of not guilty entered by direction of the court when the prisoner stood mute and by the entry, by advice of counsel, of the plea of guilty. That plea was entered under a misapprehension by counsel of the facts which induced them to consent to it, and to which it is unnecessary to refer further than to say that neither *406their good faith nor the wisdom of their action in the light they then had csm loe questioned. But the plea was entered in behalf oía prisoner who on the averment of his counsel was not mentally competent to understand the proceedings in court or to confer with them in relation to the charge of the indictment. He should not be held to be bound by it. “In a criminal case there is no warrant of attorney, actual or potential”: Prine v. Com., 18 Pa. 103. The prisoner never had a trial of the preliminary issue which was properly submitted to the jury and his right to one could not be waived by counsel.
The third, fourth and. sixth assignments of error are sustained. The judgment is reversed, and a venire facias de novo is awarded.