Insanity evaluations are symbolic of the intersection of law and psychology. However, the NGRI plea is not a frequently raised defense and can be difficult to establish. Furthermore, the burden of proof falls on the defense. This means that the defendant must prove that it is more likely than not that they were legally insane when they committed the crime.

It is important to note that insanity is not a medical or mental health term, rather a legal term. Thus, in these types of evaluations, our forensic psychologists assess the defendant’s criminal responsibility at the time of the offense, not the present moment. Evaluating current mental status and behavior would be a competency evaluation.

NGRI Legal Criteria

For a defendant to be found not guilty by reason of insanity, they must meet the jurisdiction’s definition of legal insanity. California, like many other states, follows the M’Naghten Rule as the legal definition of insanity. This was established based on the M’Naghten case in the mid-19th century. In California, PC 1026 sets the legal criteria for insanity based on the M’Naghten Rule with one additional prong brought on by way of Proposition 8.

At the time of the criminal offense, due to a mental disease or defect, the defendant was incapable of:

  • Understanding the nature of the criminal act OR
  • Understanding that what they were doing was morally wrong (differentiating between right and wrong) OR
  • Controlling their behavior at the time of the crime

For example, a woman who suffers from hallucinations and paranoia kills a person because she believes they are out to harm her. Say she is tried for murder. It is quite possible that she could be found NGRI if the psychologist found that due to her mental illness of schizophrenia, she was incapable of differentiating between right and wrong.

Unfortunately, an NGRI plea cannot be used if the behavior (criminal offense) was due to the defendant solely being under the influence of drugs or alcohol or having an addiction problem. Although it is common for individuals who suffer from substance use disorders to have a mental health problem, they cannot use the NGRI defense just because they recently used the drug(s) when committing the crime.

For example, if a man was under the influence of alcohol and killed another person, they could not use the NGRI plea.


Our Approach

Our evaluation will identify if, at the time of committing the offense, due to mental disease or defect, the defendant was incapable of:

  • Understanding the nature of the criminal act OR
  • Understanding that what they were doing was morally wrong (differentiating between right and wrong) OR
  • Controlling their behavior at the time of the crime

This evaluation will involve:

  • Consultation with the attorney to gather more information about the case and why the evaluation is being requested.
  • A thorough review of historical and current records. This will help us have a better understanding of the defendant’s onset and course of their mental illness and psychological functioning. Helpful records include:
    • Mental Health/Psychiatric Treatment Records (inpatient, outpatient, crisis response)
    • Police Reports (for behavioral observations)
    • Police Interviews (for behavioral observations)
    • Probation Reports
    • DCFS Records
    • School Records
    • Medical Records
  • Collateral interviews with parents, spouses, other family members, friends, or key witnesses to help us gather additional information about the defendant’s behavior before, during, and after the offense.
  • A clinical interview with the defendant to assess their insight into the mental illness, whether or not they were able to understand/distinguish the difference between right and wrong, whether they understood the nature of their acts, and if they were able to control their impulses and behavior at the time of the offense.
  • If needed, we will administer a battery of psychological or neuropsychological tests to objectively assess for any indications of feigning or malingering, cognitive deficits, and brain dysfunction.

Last, we will write a comprehensive report in simple language that integrates our findings, including answering the psycho-legal question of at the time of the criminal offense, due to a mental disease or defect, the defendant was incapable of:

  • Understanding the nature of the criminal act OR
  • Understanding that what they were doing was morally wrong (differentiating between right and wrong) OR
  • Controlling their behavior at the time of the crime

To learn more about our approach to insanity evaluations, contact our office at (626) 709-3494.