Luigi Mangione’s legal battle might be significantly influenced by a recent federal court ruling, as his defense team leverages this development in their argument against the Justice Department’s murder charge.

According to a new legal filing, Mangione’s attorneys drew attention to a January 13 decision by the Ninth Circuit in the case of United States v. Gomez. This ruling determined that California’s law on assault with a deadly weapon does not qualify as a “crime of violence” because of specific legal nuances. The court concluded that armed assaults could be executed recklessly—where the perpetrator should have been aware of potential danger—rather than intentionally, where harm is deliberately inflicted on the victim.

In the context of Mangione’s case, the alleged “crime of violence” involved is stalking.

“Think of it as a chain reaction,” explained Joshua Ritter, a criminal defense attorney in Los Angeles and a contributor to Fox News. “For the federal government to pursue a death penalty charge, the murder must occur during a violent felony. They require this to establish federal jurisdiction, which they attempt to achieve through the stalking charge.”

Luigi Mangione appeared at an evidentiary hearing regarding the murder of UnitedHealthcare CEO Brian Thompson, held at the Manhattan Supreme Court in New York on December 18, 2025. (REUTERS/Shannon Stapleton/Pool)

Mangione faces accusations of stalking Brian Thompson, the CEO of UnitedHealthcare, across state lines before fatally shooting him outside a New York hotel. This tragic event unfolded just hours before Thompson was scheduled to meet with shareholders for a business conference.

While in this case the alleged stalking did lead to violence, Ritter said that the defense only needs to convince that court that the crime of stalking as a whole can sometimes be committed without violence in order for the legal argument to work.

“He’s got a hell of a defense team, and they’re making some very interesting arguments,” he told Fox News Digital.

UnitedHealthcare CEO Brian Thompson pictured in an undated portrait provided by UnitedHealth. The executive was shot from behind and killed on his way to an investor conference in New York City in what prosecutors have described as a politically motivated assassination. (AP Photo/UnitedHealth Group via AP)

The defense told the New York judge that the Gomez decision supports dismissing the murder charge because the underlying stalking allegation does not meet the definition of a “crime of violence.”

The Ninth Circuit’s en banc decision isn’t binding in the Southern District of New York, where Mangione faces federal charges, said Donna Rotunno, a Chicago-based criminal defense attorney and Fox News contributor.

“[The defense] will argue that it doesn’t matter, that stalking doesn’t necessarily mean it will lead to murder, therefore it should not be used to enhance the murder charge for purposes of federal court and the death penalty,” Rotunno said.

A surveillance image released by the NYPD shows the suspect in the shooting death of United Healthcare CEO, Brian Thompson on Wednesday, Dec. 4, 2024. (NYPD Crimestoppers)

Thompson, a 50-year-old father of two, lived in Minnesota. Video shows a gunman approach him from behind and open fire before fleeing the scene.

Without an underlying violent crime, the federal murder charge that depends on it should be thrown out entirely — and the potential death penalty with it, according to Mangione’s lawyers.

According to the prosecution, the reason for the stalking was to allegedly carry out a politically motivated assassination.

“No other purpose,” Rotunno said.

Luigi Mangione shouts while officers restrain him as he arrives for his extradition hearing at Blair County Courthouse in Hollidaysburg, Pennsylvania on Tuesday, Dec.10, 2024. (David Dee Delgado for Fox News Digital)

The Ninth Circuit has a reputation for being one of the country’s most liberal federal appellate courts, and many of its decisions reach the Supreme Court, according to legal experts. The Gomez decision came down days after Mangione’s lawyers and federal prosecutors squared off in court to deliver oral arguments on the issue. His team filed a supplemental brief hoping to add weight to their arguments.

It’s unclear how the judge will rule, but other legal experts are skeptical.

“They are the most liberal circuit court in the land,” said David Gelman, a Philadelphia-area defense attorney. “They also have the highest overturn rate out of all the circuits.”

The filing may be a stretch, he said.

“The argument literally is backwards,” he told Fox News Digital. “You don’t stalk someone and say, ‘Oh, hey, I’m just having fun.’ You stalk someone with the intent to harm.”

Mangione is due back in federal court on Friday. He also faces state-level charges in New York and Pennsylvania in connection with the case.