Legal Definitions - right-and-wrong test

The right-and-wrong test is a legal standard used in some jurisdictions to determine if a defendant is legally insane and therefore not criminally responsible for their actions. It is a key component of the McNaghten Rules, a set of principles established in English law that have influenced insanity defenses globally.

This test assesses whether, at the time of committing a crime, the defendant suffered from a mental disease or defect that prevented them from understanding either:

• The nature and quality of their act (meaning they didn't know what they were doing, or didn't understand the physical consequences of their actions), OR
• That what they were doing was wrong (meaning they didn't know their act was legally or morally impermissible).

Essentially, it evaluates the defendant's cognitive capacity to understand the wrongfulness of their conduct.

Here are some examples illustrating the application of the right-and-wrong test:

• Example 1: Severe Delusional Belief

  A person suffering from severe paranoid schizophrenia attacks a stranger, genuinely believing the stranger is an alien sent to abduct their family. In this scenario, the right-and-wrong test would examine whether, due to their profound delusion, the defendant truly did not understand that attacking another human being was legally or morally wrong. If their mental illness prevented them from perceiving the reality of their actions and their wrongfulness, they might meet the criteria for legal insanity under this test.

• Example 2: Profound Intellectual Impairment

  An adult with a profound intellectual disability, whose mental age is equivalent to a very young child, takes an item from a store without paying. They do not comprehend the concept of ownership, theft, or the societal rules surrounding transactions. The right-and-wrong test would assess whether this individual's severe intellectual impairment prevented them from understanding that taking the item without payment was a wrongful act in the eyes of the law and society.

• Example 3: Psychotic Episode with Religious Delusions

  During a severe psychotic episode, an individual sets fire to a public building, convinced they are acting on direct divine command to "cleanse" the structure of unseen evil spirits. They believe their actions are righteous and necessary for a higher purpose. Here, the right-and-wrong test would focus on whether the individual, due to their extreme delusional state, genuinely believed their actions were justified and therefore lacked the capacity to understand that setting fire to a building was a legally and morally wrong act of arson, despite understanding the physical act of starting a fire.