The reason is that a person suffering from mental illness is not responsible for his actions and cannot, therefore,  undergo a trial. Mental illness is like any other illness – it incapacitates the sufferer; in this case, it is the sufferer’s mind that is incapacitated — which is worse than prdinary ailments, because, of course,  the mind controls the entire human body. A large number of illnesses, grouped under the single word depression, can deprive a human being of his mental faculties. A judge would not wish to diagnose the illness of someone who faints in his court, for instance, would he? No – it would be wrong for the judge to turn himself into a physician or doctor. Similarly, he shouldn’t turn himself into a psychiatrist, either. A psychiatrist is also a doctor, only that he deals with mental and emotional illnesses. A judge who neglects to send an accused person who shows signs of insanity to a mental hospital for him to be  professionally established as either sane or insane,  has patently infringed the constitutional rights of the accused person. And the earlier the head of the judicial service sorted out the injustice, the better. Otherwise bad judges would make slaves of all of us.