Can Mental Illness Be a Defense for Murder Charges in Vista?

Posted on: November 7th, 2025 by Dod Law

Mental Illness Defense for Murder in Vista

Facing murder charges brings overwhelming stress and fear, especially when mental illness plays a role in the alleged crime. California law recognizes that severe mental health conditions can fundamentally affect a person’s ability to understand their actions or distinguish right from wrong. The intersection of mental illness and criminal responsibility remains one of the most complex areas of criminal defense, requiring both medical understanding and legal experience to manage effectively.

For over two decades, Dod Law has represented clients throughout San Diego County facing serious criminal charges, including cases involving mental health defenses. Attorney Dod Ghassemkhani, who was named San Diego County’s Trial Lawyer of the Year by the San Diego Criminal Defense Bar Association, has handled over 100 jury trials and works extensively with mental health professionals to build defense strategies.

How Does California Define Legal Insanity?

California applies the M’Naghten rule to determine legal insanity, which focuses on whether the defendant could understand the nature of their actions at the time of the alleged crime. This standard differs significantly from a medical diagnosis of mental illness.  According to California law, a person is legally insane if they either could not understand what they were doing or could not distinguish right from wrong due to a mental disease or defect.

The prosecution bears the burden of proving sanity beyond a reasonable doubt once the defense raises the issue. That creates an essential strategic advantage, as the state must disprove insanity rather than the defense having to prove it. Mental health evaluations typically involve forensic psychiatrists or psychologists who assess the defendant’s mental state at the time of the alleged offense, not their current condition.

What Mental Health Conditions Qualify for an Insanity Defense?

Courts recognize several serious mental illnesses that may support an insanity defense:

• Schizophrenia and psychotic disorders can cause delusions or hallucinations that completely distort reality
• Severe bipolar disorder with psychotic features may create extreme manic states where rational thinking becomes impossible
• Major depressive disorder with psychotic features can lead to severe impairment in judgment and perception

Documentation of mental illness alone does not establish legal insanity. The defense must demonstrate a direct connection between the mental condition and the defendant’s inability to understand their actions or appreciate their wrongfulness. Medical records, treatment history, and expert testimony typically form the foundation of this evidence.

Does Diminished Capacity Work Differently Than Insanity?

California abolished the diminished capacity defense in 1981, but mental illness can still affect the specific intent element of murder charges. First-degree murder requires premeditation and deliberation, while second-degree murder involves malice aforethought without premeditation. Mental health evidence may show that severe mental illness prevented the defendant from forming the mental state necessary for first-degree murder, potentially reducing charges to second-degree murder or voluntary manslaughter.

How Does a Not Guilty by Reason of Insanity Verdict Work?

A successful insanity defense leads to a verdict of not guilty by reason of insanity rather than a simple acquittal. Following this verdict, the defendant undergoes an evaluation to determine whether they pose a danger to public safety. Courts may order commitment to a state mental health facility for treatment rather than prison.

The maximum commitment period typically equals the maximum prison sentence for the underlying charges. Periodic review hearings assess whether continued commitment remains necessary. Many defendants eventually receive conditional release with ongoing mental health treatment requirements and supervision.

What Challenges Do Insanity Defenses Face?

Juries often view insanity defenses skeptically, making them statistically rare and challenging to win. The general public may struggle to understand the legal definition of insanity, which differs dramatically from everyday use of the term. Television and media portrayals of the insanity defense create misconceptions about how frequently it succeeds.

Protect Your Rights With Experienced Mental Health Defense at Dod Law

Murder charges involving mental illness require immediate action from attorneys who understand both criminal law and mental health issues. The legal system offers specific protections for defendants whose mental illness affected their actions, but these defenses demand careful preparation and strategic presentation. Early involvement of mental health professionals can make the difference between conviction and a not guilty verdict.

Dod Law combines over two decades of criminal defense experience with a commitment to protecting clients facing the most serious charges. Our team works with respected forensic psychiatrists and psychologists to build comprehensive defenses for Vista clients dealing with mental health issues. Call us at our San Diego office (619) 814-5110 | Vista office (760) 814-6025 or schedule an appointment by filling out our online contact form to discuss the best way forward.