Clark v. Arizona: Summary & Decision

Instructor: Emily Cummins
In this lesson, we'll talk about an important court case called Clark v. Arizona, which revolves around the use of the insanity defense in court cases. We'll look at how laws in the State of Arizona prevented a defendant accused of killing a police officer from using the insanity defense.

Clark v. Arizona

You've probably heard of the insanity defense, or a legal clause defense attorneys use to argue that defendants with mental illness cannot be held responsible for a crime. Basically, the insanity defense is used in cases where it is believed the accused suffers from a mental illness that diminishes his or her ability to discern right from wrong.

But the insanity defense is not always so straightforward, even when mental illness is involved. Let's talk about a specific case where we see how complex the insanity defense is: Clark v. Arizona.

Summary of the Case

It all started in June of 2001 in Flagstaff, Arizona. 17 year-old Eric Clark was driving around a Flagstaff neighborhood playing loud music when a police officer stopped Clark's car. Over the past year, Clark had developed symptoms of a serious psychiatric disorder. Clark was experiencing symptoms of paranoid schizophrenia and believed an alien invasion was impending.

When officer Jeffrey Moritz stopped the car, Clark shot and killed the officer.

In the trial that followed, the defense attempted to prove that Clark was psychotic at the time of the crime and did not know what he was doing. Because of his delusions, Clark thought that he was killing an alien. The state of Arizona came up with a different argument. They set out to prove that Clark had intentionally lured the police officer to the scene by playing loud music. This theory came out of statements Clark had previously made about a desire to kill the police.

Here's a term we need to know before we go on: mens rea. Basically, this means the state of mind that person is in when he or she commits a crime. It's important in criminal defense cases because it helps us determine whether a person's mental state was such that he or she cannot be held liable for a crime.

Clark's defense would attempt to argue that the prosecution's version of Clark's mens rea (that he had knowingly killed a police officer) was false and that at the time of the crime, Clark did not know what he did was wrong.

So, what happened in this case?


After deliberations, Eric Clark was found guilty of killing officer Moritz and was charged with first degree murder. First degree murder is all about intent. In most states it means that a person knowingly and intentionally killed someone, and they likely planned it ahead.

So why did the court come to this decision, rejecting the insanity plea? The main reason here has to do with with some things that are specific to the state of Arizona.

Arizona Law

In the State of Arizona, it is not permissible to rely on evidence from psychiatric testimony to refute mens rea in a crime. This is based on a 1993 ruling by the Arizona supreme court known as State v. Mott. Put another way, even though Eric had in fact been diagnosed with schizophrenia, per the state of Arizona, this is not sufficient to totally get rid of the possibility that Eric had some intent to kill in that moment.

Arizona has a fairly narrow definition of what constitutes insanity. When deciding the mental capacity of a defendant in criminal cases, states use different tests or measures to determine whether someone meets the legal definition of insanity. Many states, Arizona included, use the M'Naghten Rule. This test basically has two parts: does a person understand that what he or she is doing and does he or she understand that it is wrong?

In this case, we're asking if Eric Clark understood what he was doing at the timehe did it, (i.e., did he know he was shooting a police officer and not an alien) and did he understand that it was wrong? In other words, did he know it was wrong to kill a police officer but he did it because he thought this was an alien, and it's OK to kill aliens?

Here's a caveat, though. Arizona eliminated the first part of the M'Naghten Rule. So, in other words, we aren't going to look at whether Eric's schizophrenia caused him not to understand what he was doing. Instead, Eric has to prove that he was insane at that moment he killed the officer. This is, as you might imagine, very difficult to do in a courtroom years after the event.

No Appeal

After the ruling Eric Clark attempted, unsuccessfully, to appeal his life sentence. He tried to argue that the state of Arizona's very narrow definition of insanity and the state's ruling in State v. Mott violate due process, or a citizen's right to equal protection under the law. Basically, due process means that every person has the right to be treated fairly in the courtroom.

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