Dedicated Texas Criminal Defender

How does the M’Naghten rule impact an insanity defense?

On Behalf of | Nov 9, 2021 | Criminal defense

TV and movies suggest that entering an insanity defense is a simple task. If these stories were reliable, you could get rid of criminal charges simply by claiming you did not know what you were doing and getting a psychiatrist to agree.

As criminal law has developed over the years, courts and states began looking at criminal insanity differently. Now, each state has a different view on making insanity defenses available and how to prove criminal insanity.

Here’s what you should know about making an insanity defense in Texas.

Following the rules

In Texas, courts follow a combination of the M’Naghten rule and the irresistible impulse test. The M’Naghten case took place in the 1840s. In this case, the jury decided that for someone to be criminally insane, they must have a “disease of the mind” that inhibits their ability to tell right from wrong.

While the M’Naghten test looks at the ability to know right from wrong, the irresistible impulse test looks at whether the defendant could control their impulses to do wrong because of a mental disorder.

The impact of M’Naghten

Looking only at whether a person with criminal charges has impulse control could lead to a conclusion too quickly. Rather than looking only at impulse control, Texas adds the M’Naghten standard.

M’Naghten adds another layer to building an insanity defense. By adding M’Naghten, the defendant was unable to control their impulses and was unable to tell that those impulses were wrong.

Burden of proof

Although a couple of states have abolished insanity defenses entirely, most states have some version of one of the four most common insanity defense tests. In the remaining states, most (including Texas) place the burden of proof on the defendant. In contrast, the remaining states require the state to demonstrate the defendant’s insanity.