Mental illness and criminal law don’t mix well.

It’s the truth. It’s the cold, hard truth.

Defendants who suffer from serious mental health conditions face particular and unique challenges in court. These challenges can completely alter the outcome of a case. It’s why it’s critically important to understand how the legal system addresses these issues.

But here’s the thing…

The legal system has a framework of laws designed to specifically address defendants who may not fully understand what they did or be able to help with their own defense. These laws are in place for a reason. It’s important to understand them.

In this post, we will be covering the following:

• The insanity defense and competency to stand trial
• Why being competent to stand trial is important
• The insanity defense
• What happens next

The Insanity Defense and Competency to Stand Trial

Mental illness in the context of criminal law means one of two things. The legal concepts of insanity and competency to stand trial are two separate mechanisms designed to protect defendants with serious mental health conditions.

And here’s where it gets interesting…

The defenses are not interchangeable and refer to different concepts in the justice system. Competency is the defendant’s current ability to be part of their own defense during legal proceedings. Insanity is the defendant’s mental state at the time the alleged criminal act took place. It’s important to understand the difference in mental health in criminal defense cases in Colorado as well as in other jurisdictions across the United States and the world.

These defenses, while they may sound dramatic, are not used nearly as often as Hollywood would have you believe. Research through the American Academy of Psychiatry and Law has found that the insanity defense is only raised in around 1% of all felony cases.

One percent, not even two.

Why Being Competent to Stand Trial Is Important

Before a defendant can even be put on trial, they must be found to be competent to stand trial.

This is non-negotiable.

For trial to be fair, defendants must have the ability to understand what they are being accused of and the consequences they face. They must also be able to work with their defense attorney to prepare their defense. If defendants are lacking in either of these abilities, trial cannot be fair.

Defense attorneys raise concerns of competency in between 8% and 15% of felony prosecutions. There are approximately 160,000 requests for competency evaluations across the United States each year.

160,000 evaluations a year.

These numbers are staggering and paint a dire picture of the criminal justice system and mental health in America.

If a defendant is deemed incompetent, treatment is ordered and the trial is put on hold. The goal is for this treatment to restore the defendant to competency to stand trial. This is a difficult, time-consuming process that could take months or longer. Treatment is designed to stabilize the defendant’s mental health to the point where they can actively and knowingly participate in their own defense.

However, there are some instances where restoration of competency may never happen. In these cases, defendants may have severe intellectual disabilities or conditions that are resistant to treatment. Charges can be dismissed or suspended indefinitely.

The Insanity Defense

An insanity defense works differently than a competency evaluation.

In this case, a defendant is acknowledging that they committed the act in question. However, they are claiming that they should not be held criminally responsible. The reason being that, at the time the alleged act took place, their mental illness prevented them from either knowing or understanding that what they were doing was wrong.

Fairly simple, no?

In reality, it is incredibly complex. The insanity defense is very difficult to successfully argue and prove. Research through the same Academy of Psychiatry and Law found that only about 26% of those who do successfully use this defense as a mental health defense were previously diagnosed with a mental health condition. The vast majority of the remaining insanity defenses were unsuccessful. Of the small minority of defendants who tried to use the insanity defense, only about 26% were successful.

There are variations in the standards used from state to state. The most common of these is called the M’Naghten Rule. This requires that a defendant must either:

• Not understand the nature of their act
• Not have known that their act was wrong

Some states have expanded this definition to include “irresistible impulse.” This means that a defendant can claim that, even if they knew what they were doing was wrong, they were incapable of not doing it due to the irresistible impulse of their mental health condition.

What Happens Next

Defendants who are found not guilty by reason of insanity do not simply walk free.

Now there’s a reality check.

In the majority of these cases, the defendant is typically committed to a psychiatric facility for treatment. This treatment can often be for longer than an equivalent prison sentence would be. And this treatment lasts until the defendant can prove to a judge that they are no longer a threat to themselves or others. Most defendants are hospitalized until they are able to meet this burden of proof.

There is a different verdict that is sometimes used in some jurisdictions. Guilty but mentally ill. This verdict takes into account a defendant’s mental illness, but the defendant is still held criminally responsible and the defendant serves their sentence in a treatment facility.

There is an increase in what are known as mental health courts. These are courts that are set up to divert defendants into treatment programs instead of going through traditional criminal prosecution.

And why does any of this matter?

Because the traditional criminal justice system was never designed to be a mental health treatment provider. In fact, there are studies to suggest that jails and prisons have been poorly suited for the purpose and thus people with mental illness are significantly overrepresented. Some studies have found that the prevalence of mental illness in jails and prisons is around 44% and 37%, respectively. This is compared to 18% in the general public.

These different verdicts and mental health courts take into account that the traditional punitive measures do not offer a solution to the underlining cause.

Bringing It All Together

The criminal legal system has an approach to defendants with serious mental health conditions. This approach is designed to be a balance between the rights of the individual and public safety.

The legal defenses of insanity and competency are used to provide this balance. It is important to understand them if you are facing criminal prosecution.

Let’s bring it all together:

• Competency is current mental ability
• Insanity is mental state at the time of the alleged criminal act
• Both are different and have different implications for the defense
• If a mental health defense is successful, the defendant will most likely not be going free

The system is flawed. It is incredibly backed up and defendants have to wait a long time to receive a competency evaluation. Even if a defendant is competent to stand trial, there is an overwhelming lack of treatment facilities to meet the need. We have a long way to go to fixing this system.

But at least there is a recognition that mental health matters in the criminal justice system. Defendants with serious mental health conditions can, in fact, have their mental health condition taken into consideration during criminal trials. It may not be perfect. But it’s a start.

Last modified: January 13, 2026