The Insanity Defence

A lot of our perceptions of lawyers are shaped by what we see on television shows or in the movies. It can be hard to see where a good story ends and reality begins, so it is difficult for the everyday man to understand what a criminal lawyer in Sydney’s Inner West does on a day-to-day basis. Being a lawyer in Sydney’s Inner West is not the same as being a lawyer on Boston Legal or Ally McBeal.

However, one thing that appears in those sorts of television shows and movies that appears from time to time in the working life a lawyer is the insanity defence. The insanity defence is often used in drama to cause conflict in a story, and writers take artistic licence with their depiction of this form of defence. So what really is the insanity defence?

The Basics:

The insanity defence can be used to allow a defendant who was seriously mentally impaired at the time of committing an offence to escape a conviction.

Seriously Mentally Impaired?

The test for the insanity defence involves asking two questions:

  1. Was the accused functioning under a defect of reason due to a disease of the mind?

  2. Because of this disease of the mind, did the accused not know the nature and quality of their act; or did they not know what they were doing was wrong?


Above ‘disease of the mind’ refers to any mental disorder that manifests itself in violence and can recur, like schizophrenia. It does not include external influences like intoxication, and it must be a disorder, so simply being an average man in a highly emotional state does not count.


If the insanity defence is proven to be true, one of two results usually follows:

  • The person is detained in such a way the court sees fit (like a mental institution), until the court chooses to release the person; or

  • The person is released after the court is satisfied that the safety of the person and the general public will not be endangered by the person’s release.

If you are seeking a criminal lawyer or a solicitor in Sydney’s Inner West, visit CM Lawyers or call (02) 9568 6266