Maintenance of an insanity defense under Montana's "abolition" of the insanity defense

In 1979, Montana's insanity defense was replaced with the more restrictive mens rea defense, a change that has been described as an example of "abolition" of the insanity defense. The authors identified cases in which mental health was an issue in seven Montana counties for 3 years before and 3 years after the 1979 reform. They found that acquittals based on the insanity plea markedly declined, but that dismissals based on incompetence to stand trial increased substantially following the reform. They conclude that dismissal based on incompetence to stand trial became a substitute for acquittal based on the insanity plea under mens rea.