Arriving in court dressed in prison attire and in handcuffs, Mangione acknowledged his understanding of the indictment before stating "not guilty." This hearing marked a pivotal moment, with federal prosecutors formally moving to seek capital punishment, emphasizing that the murder was aimed at igniting an ideological fight against the health insurance industry, as stated by US Attorney General Pam Bondi.

Controversy surrounds the case, with Mangione's defense team labeling the pursuit of the death penalty as "barbaric." During the 35-minute hearing presided over by Judge Margaret Garnett, both sides discussed pre-trial logistics with the judge acknowledging the extensive nature of the evidence, which includes around three terabytes of information from multiple sources—a factor that means a federal trial will not commence until 2026.

Furthermore, Mangione's attorney raised concerns regarding potential constitutional issues if the death penalty case were to be tried in federal court after a state trial. The judge ordered written explanations from the prosecution about ensuring Mangione’s access to private communication lines with his legal team, reflecting the ongoing legal complexities surrounding his case.

The murder of Thompson, shot dead on December 4, has sparked conversations about the challenges within privatized healthcare, with some protesters even portraying Mangione as a folk hero for his actions. Demonstrations occurred outside the courthouse, where symbolic shell casings inscribed with words like "deny" and "defend" were found at the crime scene, connecting the murder to wider discontent toward the healthcare system's profit-driven motives. Public sentiment and financial contributions towards Mangione's defense underscore the deep-seated frustrations related to healthcare issues in the U.S.