Sorry, I forgot I wanted to comment on ths too. Someone mentioned the idea of 'criminally insane' somewhere in this thread. To be so labeled means that you were so impaired by their mental illness that they lost the capacity to determine right from wrong. It is harder than television makes it out to be to stick.

However, everyone in prison can be found to have, at the very least, a personality disorder by virtue of the fact that they are in prison. i.e Antisocial Personality Disorder. Therefore, just by being arrested they are no longer 'completely sane and aware' - emphasis on 'completely'.