Ala. Code § 15-16-1: Defense of Insanity to Be by Special Plea.

When the defense of insanity is set up in any criminal prosecution, it must be by special plea, interposed at the time of arraignment and entered of record upon the docket of the court, which, in substance, shall be “not guilty by reason of insanity.” A plea of insanity shall not preclude the usual plea of the general issue, which shall not, however, put in issue the question of the irresponsibility of the accused by reason of his alleged insanity, this question being triable only under the special plea.