Section 134, THE CRIMINAL PROCEDURE ACTS, 1965

If any person stands mute or refuses, or by reason of infirmity is unable to answer directly to the indictment the Court shall, unless it has reason to believe that such person is of unsound mind and consequently incapable of making his defence, order the Registrar to enter a plea of not guilty on behalf of such person, and the plea so entered shall have the same force and effect as if such person had actually pleaded the same; but if the Court has reason to believe as aforesaid, it shall proceed in the manner prescribed in section 71. Conduct and precedence of prosecutions.