The Supreme Court on Monday threw out the conviction of a Pennsylvania man convicted of making threats on Facebook, but dodged the free speech issues that had made the case intriguing to First Amendment advocates.

Chief Justice John Roberts, writing for seven justices, said it was not enough for prosecutors to show that the comments of Anthony Elonis would make a reasonable person feel threatened.

But the court did not specify to lower courts exactly what the standard of proof should be.

Elonis was prosecuted under a law banning illegal threats after he posted Facebook rants in the form of rap lyrics about killing his estranged wife, harming law enforcement officials and shooting up a school.

Elonis claimed the government had no right to prosecute him if he didn't actually intend his comments to be threatening to others. He argued that his musings were protected by the First Amendment. But the Obama administration said the test is whether the comments would strike fear in a reasonable person.

The high court said it was not necessary to reach First Amendment issues in reversing Elonis' conviction. Roberts said the reasonable person standard is "inconsistent with the conventional requirement for criminal conduct -- awareness of some wrongdoing."

Elonis said he didn't intend to threaten anyone. He claimed his posts under the pseudonym "Tone Dougie" were a form of therapy that allowed him to cope with the breakup of his marriage and being fired from his job at an amusement park.

His lawyers said the comments were heavily influenced by rap star Eminem, who has also fantasized in songs about killing his ex-wife. But Elonis' wife testified that the comments made her fear for her life and she persuaded a judge to issue a protective order.

The government argued that it didn't matter whether Elonis actually intended to threaten anyone. If the comments provoked sufficient fear and anxiety to make people feel threatened, that was enough to prosecute it as a crime.

One post about his wife said, "There's one way to love you but a thousand ways to kill you. I'm not going to rest until your body is a mess, soaked in blood and dying from all the little cuts."

After his wife obtained the protective order, Elonis wrote: "Is it thick enough to stop a bullet?"

Those and other comments led to his arrest. A jury found Elonis guilty under a law barring interstate communications that contain "any threat to injure the person of another." He was sentenced to nearly four years in federal prison and was released last year.

Elonis was arrested again in April for allegedly throwing a pot that hit his girlfriend's mother in the head. Police charged him with simple assault and harassment.