Two main groups of people lack capacity for criminal responsibility - the very young and the mentally disordered.
Under s13 of the Criminal Code, no person shall be convicted of an offence for an act or omission committed while under the age of 12 years. This provision replaces the common law rule that children under age 7 lack capacity for criminal intent, but that children between 7 and 14 may be demonstrated to have that capacity.
Balance of Probabilities
Under s16 of the Criminal Code, no person is responsible for an act or omission committed while suffering from a mental disorder rendering the person incapable of either a) appreciating the nature and quality of the act or omission, or b) knowing it was wrong. People are presumed to be sane; mental disorder must be proved on a balance of probabilities. The burden of proving mental disorder lies on the party raising it. Usually this is the accused, although the prosecution may prove mental disorder if the accused brings sanity into issue during trial or after a finding of guilt but before the entry of the verdict. The allocation of the burden of proof has been sustained under the Charter.
The incapacity must be caused by "mental disorder," which the Criminal Code defines to be "disease of the mind." The common law defines "disease of the mind" to include any illness, disorder or abnormal condition which impairs the human mind and its functioning, excluding self-induced states caused by intoxicants (unless past intoxication has caused brain damage) or transitory mental states such as hysteria or concussion. Diseases of the mind may arise from organic brain dysfunction, psychological processes or physiological conditions. Psychiatric evidence is relevant to but not conclusive of whether a particular condition constitutes a disease of the mind.
The disease of the mind must cause either of the incapacities. Incapacity to understand the nature and quality of an act or omission refers to the incapacity to appreciate the nature and physical consequences of an act or omission; eg, whether the act of stopping breath will result in death. It does not refer to the capacity to experience appropriate emotional responses to the act or omission.
Incapacity to know that the act or omission was wrong refers to the incapacity to know that the general type of act or omission and the particular act or omission in question were morally wrong or contrary to society's moral standards. An accused does not lack this capacity just because of mere nonadherence to society's moral standards, so long as the accused is capable of knowing those moral standards.
If an accused is found to have been suffering from the requisite mental disorder at the time of committing the act or omission, neither acquittal nor conviction follows. Rather, the verdict is "not criminally responsible on account of mental disorder." Upon the rendering of this verdict, the court may hold a disposition hearing; if it does not, the hearing is held within (generally) 45 days before a Review Board constituted under the Criminal Code. A Review Board is established for each province, and consists of at least 5 provincial appointees. The accused is entitled to certain due process protections at the hearing. After taking into account the need to protect the public from dangerous persons and the accused's mental condition, reintegration into society, and other needs, the court or Review Board imposes the least onerous and restrictive of the following dispositions: a) an absolute discharge, if the court or Review Board concludes that the accused is not a significant threat to public safety; b) a discharge on appropriate conditions; or c) detention in custody in a hospital, on appropriate conditions. Appeals lie from disposition decisions, and dispositions other than absolute discharges are reviewable at least annually.
Mental disorder at the time of an offence must be distinguished from mental disorder at the time of trial. It may be proved on a balance of probabilities that mental disorder has rendered an accused unable to conduct a defence or to instruct counsel to do so; in particular, the accused may be unable to understand the nature and object of the proceedings, their consequences, or to communicate with counsel. In such a case, the accused is "unfit to stand trial" under the Criminal Code. If an accused is found to be unfit, he or she cannot be tried, but goes before the Review Board for an appropriate disposition. Generally, if the accused later becomes fit and if a case against the accused remains to be met, the accused may then be tried.
The Criminal Code does not make provision for unfitness to stand trial not caused by mental disorder. Where nonmental disorder unfitness has been established, some courts have stayed proceedings against the accused on the basis that a trial would be contrary to the principles of fundamental justice.