What is the standard of proof required for an accused to establish a mental disorder defence?

The standard of proof required for an accused to establish a mental disorder defense is on the balance of probabilities. This means that the accused must demonstrate that it is more likely than not that they were suffering from a mental disorder at the time of the offense, which affected their capacity to understand their actions or their ability to discern right from wrong.

In legal terms, "on the balance of probabilities" means that the evidence presented must lead the decision-maker to conclude that the proposition (in this case, the mental disorder) is more likely true than not. This contrasts with the standard of "beyond a reasonable doubt," which is the higher burden of proof required for the prosecution in a criminal case. The other standards mentioned do not apply in this context; the "preponderance of evidence" typically refers to civil cases, while "clear and convincing evidence" is a higher standard often applied in specific civil contexts, not generally in criminal defenses like mental disorder. Therefore, establishing a mental disorder defense rests on the lower threshold of proof, which is on the balance of probabilities.