Luigi Mangione
One of the killers in my Privileged Killers was the son of a renowned San Francisco, and –no surprise– he got off easy using an insanity defense back in the early 1970s after terrorizing the city for months. While Luigi Mangione isn’t charged with serial killings (just killing the CEO of UnitedHealthCare), he did want to use the “Extreme Emotional Distress” (EED) defense which is, let’s say, Insanity Lite.
Courts in San Francisco County and throughout California allowed a highly specific alternative to a full insanity plea in 1973 and 1974. However, it was not called “Extreme Emotional Distress” (EED)—instead, it was known as the “Diminished Capacity” defense. [1, 2]
California has historically rejected the specific Model Penal Code formulation of EED, choosing instead to rely on its own unique, homegrown doctrines for evaluating a defendant’s mental state. [1, 2] The framework allowed by San Francisco courts during that specific 1973–1974 window operated under the following mechanisms:
The Legal Alternative: Diminished Capacity
So, in 1973 and 1974, California operated under a “bifurcated trial” system. If a defendant pled Not Guilty by Reason of Insanity (NGRI), the trial was split into a guilt phase and a sanity phase. [1, 2]
To avoid the strict, all-or-nothing nature of the insanity defense, the California Supreme Court (through landmark cases like People v. Wells and People v. Gorshen) established the Diminished Capacity defense. This allowed defense attorneys to introduce psychiatric evidence during the guilt phase of the trial. [1, 2, 3, 4, 5]
First-Degree Murder
Instead of claiming the defendant was completely insane, psychiatrists argued that a mental condition prevented the defendant from actually forming the specific intent, premeditation, or malice aforethought required for a first-degree murder conviction. If successful, it effectively downgraded murder charges to voluntary or involuntary manslaughter. [1, 2, 3, 4]
What a Psychiatrist Had to Prove (1973–1974)
Unlike modern clinical standards governed by the DSM-5, forensic psychiatry in California courts during the early 1970s relied heavily on psychoanalytic concepts pioneered by influential figures like Dr. Bernard Diamond. [1]
A psychiatrist did not have to prove a singular, specific medical diagnosis (like schizophrenia or bipolar disorder) to establish diminished capacity. Instead, they had to prove a functional clinical impairment caused by any recognized “mental disease, mental defect, or psychopathology”. [1, 2, 3]
To successfully establish the defense, the expert’s testimony had to prove the condition disrupted specific mental faculties: [1]
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- Inability to Maturely and Meaningfully Reflect: Under the governing case at the time—People v. Wolff (1964)—the psychiatrist had to show that even if the defendant planned the crime, their mental illness left them unable to “maturely and meaningfully reflect” upon the gravity of their actions. [1, 2]
- The “Gorshen” Block: The expert had to prove that an underlying condition (such as severe clinical depression, trauma, chronic psychosis, or organic brain damage) acted as a mental block, destroying the defendant’s capacity to harbor “malice aforethought”. [1, 2, 3]
- Voluntary Intoxication and Trauma: In 1973–1974, psychiatrists could also couple an underlying mental weakness with acute intoxication. They would argue the combination triggered a brief, transient state where the defendant lost control of their cognitive boundaries. [1, 2]
The Evolution and Demise
This highly permissive system is what eventually led to San Francisco’s notorious 1979 “Twinkie Defense” trial. In that case, defense psychiatrists successfully used the Diminished Capacity framework to argue that former Supervisor Dan White’s severe depression (evidenced in part by a sudden shift to a junk-food diet) meant he lacked the capacity to premeditate the assassinations of Mayor George Moscone and Supervisor Harvey Milk. [1, 2]
The immense public backlash from that San Francisco verdict prompted California voters and lawmakers to completely abolish the Diminished Capacity defense in 1982. [1, 2]
Worries about a 2026 backlash?
I used the word “Proposed” in this blog title because Mangione’s lawyers withdrew their planned EED defense a day later. They may’ve feared a similar backlash in public opinion as happened in California. Also, Mangione is also facing a federal trial slated for early 2027, and an EED defense might’ve impacted that trial.
