Three men facing serious criminal charges in Arkansas are examples of how courts must reconcile the goals of prosecutors, the needs of the mentally ill and the protection of the community.

The aim of prosecutors is to punish law breakers, protect the community and impose rehabilitative measures when warranted. But when alleged offenders lack the capacity to understand they broke laws, lack understanding of what is happening in court and cannot assist their defense lawyers, the justice system is often left in a quandary.

Vinson Marks, 27, has been back and forth between...