The Insanity Defense in California Courts

Posted in Criminal Defense on February 19, 2019

A defendant in a California criminal case will have two options to plea during an arraignment, or an initial hearing: guilty or not guilty. Within these two main options are subcategories. One option within the not guilty plea is the insanity defense. Using this defense means the defendant is admitting to committing the crime, but pleading not guilty by way of mental deficits. The insanity defense derives from the theory that mental defects can prevent an individual from having the intent to commit a crime – thus making that person not guilty.

History of the Insanity Defense

The case that formalized the insanity defense in the U.S. justice system was the M’Naghten case of 1843. In this case, a man named Daniel M’Naghten shot and killed a man he thought to be the Prime Minister. He actually murdered Edward Drummond, the Prime Minister’s secretary. M’Naghten committed the act because he believed the Prime Minister was conspiring to kill him, and so acted in self-defense. M’Naghten and his attorney pled not guilty by way of insanity, and medical experts testified that he was psychotic. The courts ruled him not guilty.

After this case, the Lords of Justice in England created an official definition of criminal insanity. It stated that this was only a defense to criminal charges if the defendant had such a defect of reason, from a mental disease, as to not understand the nature of the act he or she was committing, or else to not understand what he or she was doing was wrong. Today, the technical definition of criminal insanity depends on the jurisdiction, but most are similar to the original M’Naghten rule.

What Is the Insanity Defense?

The insanity defense involves the two key elements of a crime: mens rea and actus reus. Mens rea is Latin for guilty mind, while actus reus means guilty act. For the courts to convict someone of a crime, both of these elements must exist simultaneously. The defendant must have had the knowledgeable intent to commit the crime, and he or she must have actually committed the act. It is not enough to convict someone for simply thinking about committing a crime; nor is it enough to convict without establishing criminal intent.

Mental health problems can interfere with the ability of someone to form criminal intent. This takes away mens rea, and can thus lead to a not-guilty verdict. The California courts can use a few different standards, including the M’Naghten rule, in determining a case involving an insanity plea.

• Irresistible impulse: This standard gauges the defendant’s ability to control his or her actions.
• The Durham rule: This standard asks whether the crime was the product of a mental defect.
• The Comprehensive Crime Control Act: This standard looks at whether the defendant knew the difference between right and wrong.

Psychiatrists are integral in cases involving an insanity plea. They work with defendants as patients, and then testify as to the defendant’s mental condition or defects. A successful insanity defense does not mean the defendant walks free. It does not convict the person of the crime in question, but it can lead to mandatory sentencing. In most cases, a judge will order non-optional entry into a mental health institution, either for a specified period of time or for life. Defendants should not take the insanity defense lightly.

When Is This Defense Appropriate?

Pleading not guilty by way of insanity is an option a defendant may have if he or she has a formal mental disease or defect diagnosis from a psychiatrist, and if this defect caused the defendant to commit the crime in question. A criminal lawyer may recommend taking the insanity defense if the defendant has a mental deficit that could qualify under one of the California court standards. This defense could prevent criminal conviction and jail time, although it will likely lead to required treatment or institutionalization.