Luigi Mangione's lawyers will argue that he was not mentally stable when he killed UnitedHealthcare CEO Brian Thompson. They are not saying he didn't pull the trigger. Instead, they are saying his mental state at that moment was so disturbed that it should reduce his charge from murder to manslaughter — a crime with much lighter punishment.

This legal move is called an "extreme emotional disturbance" defense. Under New York law, if a jury believes this argument, the charge automatically drops from second-degree murder to first-degree manslaughter. State Judge Gregory Carro confirmed this is the defense strategy, CBS News New York reported.

Why doesn't the defense just claim Mangione didn't know what he was doing? That's a different argument, called an insanity defense, and it's much harder to prove. The extreme emotional disturbance defense is narrower. It means: yes, he knew it was wrong, but his emotional state was so severe that a reasonable person in his situation might have done the same thing. The gun and notebook found near his arrest were entered as evidence in May 2026.

The case has already changed shape. Terrorism charges were dropped in September 2025, leaving only the murder charge in New York state court. At the same time, his lawyers asked federal prosecutors not to pursue the death penalty in a separate federal case. The two cases — state and federal — run on different tracks.

Some court records were sealed in early June 2026, closed to the public and news media. This kind of sealing is rare in cases that attract this much public attention.

The defense's strongest option at the state level is the mental state argument. There is a lot of physical evidence against Mangione. The challenge here is not whether he did it — it's whether his mind was broken enough that the law should treat it differently. His lawyers will likely point to physical or emotional suffering he experienced before the killing. A jury will have to decide if that suffering was severe enough to qualify as "extreme emotional disturbance" under the law.

People's reactions to Thompson's death have ranged from sadness to anger at the health insurance industry. That complicates finding a fair jury. People on both sides may arrive at court with their minds already made up.

Mangione also faces separate federal charges. Those charges can still result in a death sentence even if he is convicted of manslaughter in New York state. That is why his defense team is fighting hard on both fronts.