What is the name of the ruling established in 1843 that pertains to a defendant's mental state and the criteria for their insanity defense?

The ruling established in 1843 that pertains to a defendant's mental state and the criteria for their insanity defense is known as the M'Naughten Rule. This rule provides a legal standard for determining whether a defendant can be exempt from criminal liability due to mental illness. Specifically, it states that a defendant may be found insane if, at the time of the crime, they were suffering from a severe mental disease or defect that affected their ability to understand the nature of their actions or to distinguish right from wrong.

The M'Naughten Rule is significant in legal contexts because it requires a clear demonstration of the defendant's mental state at the time the offense was committed, thus impacting the outcome of many criminal cases involving claims of insanity. It has influenced legal standards and is frequently referenced in discussions regarding mental health and criminal responsibility today.

Other options, while related to legal standards surrounding mental health and criminal culpability, do not pertain to the historical foundation like the M'Naughten Rule does. Therefore, the M'Naughten Rule is the correct answer as it directly pertains to the insane defense criteria established in 1843.