Just as violent criminals have that right suspended by a court action, so also a mentally deranged person can be similarly suspended. We also have a right to walk around freely---unless and until we are incarcerated for the commission of a crime. Exercise of rights is meant for responsible adults. If by bad behavior or mental deficiency an adult cannot be trusted to be a responsible citizen, they can be restricted in their liberty. Otherwise, it is no different than letting children play with hand grenades.