¶1delivered the opinion of the court. The evidence in this case looks towards a substitution of an instrument of a larger amount, for the one the defendant supposed he was executing. Had it been made out satisfactorily that there had been a note drawn for a smaller amount, that the defendant. was defrauded into executing the note in question, by its substitution at the moment of execution, I cannot perceive any objection to the admission of such proof; and if made out, I think it would avoid the instrument upon the issue of non est factum, Chitty lays it down, that the defendant, on non est factum, may give in evidence that the deed was void at com-? pion law, ab initia; as that it was obtained by fraud, &c. (Chitty, Pl. 479.) The fraud he refers to, must have been a fraud relating to the execution of the deed, for the issue involves only the execution of the instrument. In the case of an infant, he must plead infancy, and cannot give it in evidence on non est factum, because the deed is his, though he is not bound by it. A feme covert, having no capacity to contract, is not bound to plead coverture. If a deed be mis-read, or mis-expounded, to an unlettered man, this may be sliown on non est factum, *339because he has never assented to the contract: So, if a man be imposed upon, and signs one paper while he believes he is signing another, he cannot be said to have assented, and may show this on non estfactum.
¶2I will not pretend to say ethat there is not a great deal of technicality in the application of the rule, as to the cases in which you may give evidence impeaching the execution of the instrument, under the plea of non est factum, and those in which you may not. In the present case, the defendant was not unlettered, and there is not sufficient proof to warrant the verdict, that there was a substitution of one instrument for another. There must be a new trial.
¶3New trial granted,