In Re People v. Rosas

Summary

The court held that evidence that a mental disease or defect prevented a defendant from forming the culpable mental state required for an offense is evidence relevant to insanity. A defendant charged with specific-intent crimes therefore must first plead not guilty by reason of insanity before introducing that evidence; the statutory provision permitting mental-condition expert evidence without such a plea does not apply when the evidence concerns insanity. The court exercised original jurisdiction, made the rule to show cause absolute, and remanded for the defendant to choose whether to plead not guilty by reason of insanity.