DEAF AND DUMB, in Law. The Roman law held deaf and dumb persons to be incapable of consent, and consequently unable to enter into a legal obligation or contract. Both in England and Scotland they may make contracts or wills if they have the use of reason and understand the nature of their undertaking, and express their consent intelligibly. Although the presumption of law is that a deaf and dumb person is in the same state as an idiot, and incapable of any understanding, such a one may be subjected to a criminal trial on proof that he knows right from wrong. And, if he understands the nature of an oath, and is possessed of intelligence, he may give evidence as a witness by signs through an interpreter or by writing. It is always a good objection to a jurymen that he is deaf and dumb.
In the United States, in general, the legal presumption of the common law as to the mental incapacity of the deaf and dumb does not exist. They are presumed to be capable of comprehending the nature of crime, the nature and obligation of an oath, and of making any contract; hence may be indicted, tried, and punished for crime, and may testify as witnesses. The federal courts have no peculiar jurisdiction as to persons deaf and dumb, but the act of congress prescribing punishment to be inflicted upon 'every person' who is guilty of certain acts prohibited, includes every person possessed of sufficient mental capacity for criminal responsibility, although they may be deaf and dumb. The federal courts are governed by the practice of the states in which the cause is pending as to the competency of a deaf and dumb person as a witness, and this competency will be determined in either state or federal court by the judge before whom the cause is pending, upon examination of the individual, and upon testimony of those acquainted with the party. A deaf and dumb person is legally incapacitated to serve as a juror, or for service in the army and navy, but in other respects has the rights of citizenship.