Kurt Havelock, who did not attack, was convicted in 2008 of mailing threatening messages after he sent a disjointed "econopolitical" letter to media outlets that promised to "test the theory that bullets speak louder than words."
Havelock instead turned himself in to police, saying he changed his mind after sending the statements and taking a semiautomatic weapon and ammunition to a parking lot near University of Phoenix Stadium in Glendale, Ariz., where people had begun to gather before the game.
A full 11-judge panel of the 9th U.S. Circuit Court of Appeals ruled 9-2 Friday that Havelock's rambling message did not violate the law because it was addressed to corporations, not individuals, according the Los Angeles Times.
Judge Betty Fletcher wrote in the majority opinion that the law refers to communications containing "any threat to kidnap any person or any threat to injure the person of the addressee or of another."
Those terms mean people, not media entities, she said, according to the San Francisco Chronicle.
"It simply makes no sense to threaten to kidnap a corporation, or injure 'the person' of a corporation," Fletcher said.
Judge Raymond Fisher wrote in dissent that while the letters were not directed at any specific person, they were a threat to the general public.
"Unlike the majority, I see no reason to preclude liability ... when a threatening communication is addressed to, and threatens mass murder against, a community rather than a specific individual," Fisher wrote.
Havelock's lawyers said the letters were not meant as a threat, but as a posthumous explanation, since he expected to be killed during the attack.
Havelock, a former restaurant owner, told the FBI he was angry over the Tempe City Council's rejection of his liquor application, according to court documents.
In response, he mailed an eight-page manifesto to The Associated Press, Los Angeles Times, New York Times, and Phoenix New Times, promising what he called an "econopolitical confrontation."
"I will not be bullied by the financial institutions and their puppet politicians," Havelock wrote, according to an FBI complaint.
"I will test the theory that bullets speak louder than words. Perhaps the blood of the inculpable will cause a paradigm shift. ... Someone has to start the revolution but no one wants to be first."
Havelock was sentenced to a year and a day in prison, which he has already served.
A spokesperson for the U.S. attorney's office in Phoenix didn't say whether the government would appeal Friday's ruling, telling the Los Angeles Times that prosecutors were "studying the opinion to review our options."
Information from: Los Angeles Times, http://www.latimes.com