From ArticleWorld

Sanity is used to indicate that a person can be held legally responsible for their actions as they are of sound mind. It is not a medical term but a legal one, but it is a psychiatrist who determines whether a person is sane or not.

Sanity should not be confused with mental illness as it is possible to be mentally ill yet perfectly sane or to be judged insane without there being a mental illness.

What is sanity?

There is no one definition of sanity but a theory of sanity was put forward by Alfred Korzybski, who maintained that humans could not experience the world directly but through abstractions. Sometimes the understanding of what is happening is not consistent with the structure of what is actually going on.

Insanity as a defense

Defense by reason of insanity has existed since ancient times but it is a controversial strategy nowadays. It is still used in the US but has been changed in many Commonwealth countries to ‘mental disorder defense.’ If it is judged that a person could not appreciate the nature of their actions at the time of carrying them out, then they cannot be found guilty of wrongdoing. It makes no difference if they are completely sane before or after. If a person has been found not guilty by reason of insanity, they are usually required to undergo psychiatric treatment until it is judged they are no longer a threat.

Criticisms of the insanity plea are that it is too subjective as there is no one definition of insanity and that it seems that the bigger the crime, the more insane the defendant.