Reasons for a defendant's refusal to invoke an insanity defense include the belief that they are not guilty and therefore entitled to a full acquittal, a reluctance to believe they are mentally ill, and a preference to spend time in jail or prison rather than in a mental hospital. When the insanity defense is inserted over a defendant's objections, it raises the question of differences between this defense and others which justify this unusual approach by trial courts, defense counsel, or prosecutors. A trial judge may consider advancing the insanity defense as just or necessary; the mere hint or presence of mental illness is likely to set a defendant apart as a special species. Further, a judge may believe that an insanity acquittal is the only way to obtain treatment for the defendant either in the defendant's or the society's interest. The court may also feel that hospitalization for mental illness after an insanity acquittal is the only way to incapacitate the defendant, especially when the crime, is minor and the defendant would not be imprisoned for long if convicted. The defense counsel has a duty to bring doubts of a client's competency to the court's attention with or without the client's permission. Moreover, attorneys are likely to be influenced by many of the same considerations that influence trial judges. However, many court rulings have upheld a competent defendant's decision not to risk State hospital confinement regardless of whether an insanity defense might be viable. Such reasoning asserts that a defense which affects 'substantial rights' is a decision akin to the decision of how to plead and belongs to the client alone. Yet a defense counsel's failure to investigate a possible insanity defense places the case in jeopardy if later challenged on grounds of incompetence of counsel. If a defendant objects to the use of the insanity defense, the attorney should record the fact that the defendant was fully informed of the possible results of not relying on such a defense. The attorney may also raise the issue of insanity despite the client's wishes after first moving for bifurcation of the trial to submit the issue of guilt to the jury before any consideration of the defendant's sanity. Some State statutes permit the prosecution to interject the insanity defense into the case in the interest of justice. Due to posttrial considerations, it would also be better for the prosecutor to bring the evidence of nonresponsibility to the attention of the court. Over 180 footnotes are provided.