In many criminal offences the prosecution must prove, among other elements, that the accused had the intention to commit the act and intended to achieve the end result. It can be a defence to certain charges where the intention is not held.
In relation to Commonwealth offences, the criminal law on intent can be found in section 5.2 of the Criminal Code Act 1995 which provides that a person has intention with respect to conduct if he or she means to engage in that conduct. This is known as voluntariness. Further, a person has intention with respect to a circumstance if he or she believes that it exists or will exist. This is the belief held by a person. A person has intention with respect to a result if he or she means to bring it about or is aware that it will occur in the ordinary course of events and this is known as intended consequence.
A person who does not commit an act voluntarily, holds a mistaken belief or did not intend the consequence achieved may be in a position to raise a defence of lack of intent. However it must be noted that lack of intent is not always a complete defence. People are often charged on the basis that their actions were reckless and fault is attributed on that basis.