Pleading Insanity in an Arizona Criminal Case

The “insanity defense” may be the most misunderstood concept in criminal law. In Hollywood it feels like an easy way out; in real-life Arizona courtrooms it is rare, difficult to prove, and—when successful—usually leads to long-term commitment in a locked psychiatric facility rather than a walk-out-the-door acquittal.

What Does It Mean to Plead Insanity?

Under A.R.S. § 13-502 (Arizona’s insanity statute), a defendant is not criminally responsible if, at the time of the offense, he or she was suffering from a “mental disease or defect” that rendered the person incapable of either:

• Understanding the nature and quality of the act, or
• Knowing that the act was wrong.

Because nearly every crime requires a “guilty mind” (mens rea), proving the absence of that capacity can negate criminal liability.

Who Has the Burden of Proof?

In Arizona, the defendant bears the burden of proving insanity by “clear and convincing evidence.” That is a higher bar than “preponderance of the evidence,” but lower than “beyond a reasonable doubt.” Typically the defense must present:

• Comprehensive psychiatric evaluations
• Medical and mental-health records
• Expert testimony from forensic psychologists/psychiatrists
• Collateral evidence (school, employment, family history, etc.)

How Do Courts Measure Legal Insanity?

States use one (or a hybrid) of four historic tests. Arizona relies on a modified M’Naghten standard embedded in § 13-502, focusing on knowledge of wrongfulness or the nature of the act.

Test	Key Question
M’Naghten	Could the defendant understand what he was doing or that it was wrong?
Irresistible-Impulse	Could the defendant control his actions?
Model Penal Code	Did a mental disease prevent the defendant from appreciating criminality or conforming conduct to law?
Durham	Would the crime have happened but for the mental illness?

What Happens If the Defense Succeeds?

• The verdict is “Not Guilty by Reason of Insanity (NGRI).”
• The judge immediately commits the person to the Arizona State Hospital for evaluation.
• Release is possible only after doctors and the Psychiatric Security Review Board deem the patient no longer a danger—often years or decades later.

Do All States Allow an Insanity Defense?

No. Four states (Idaho, Kansas, Montana, Utah) have abolished traditional insanity pleas. Arizona still recognizes it, but also permits a “guilty except insane” verdict in certain cases, blending criminal and mental-health dispositions.

Is the Insanity Defense Right for Your Case?

Because insanity claims can backfire—juries are skeptical and failed attempts may look like admissions of the act—you should never pursue this route without skilled counsel and a vetted forensic team.

Ted Law’s Approach

• Early psychiatric screening & selection of top experts.
• Strategic decision-making: full NGRI, partial responsibility, or alternative defenses.
• Negotiations with prosecutors for “guilty except insane” outcomes where appropriate.

Ted Law serves clients across Maricopa County, including Scottsdale, Chandler, Mesa, Phoenix and Arizona State University.