The Supreme Court ruled Monday that making threats to someone on social media might be illegal only if the government can prove some measure of intent to make good on the threat. In a decision that could be considered a setback for law enforcement and advocates for victims of domestic violence, justices said they favored plaintiff Anthony Elonis and others like him whose threatening words on websites such as Facebook and Twitter may instill fear but do not prove criminal intent under a federal statute.

Chief Justice John Roberts, who wrote the majority opinion in the 8-1 ruling, said the court was not basing its decision on a broad interpretation of the First Amendment right to free speech, USA Today reported. That could mean Elonis, a divorced and unemployed Pennsylvania man convicted of making murder threats on Facebook against his ex-wife, could be found guilty under a tougher standard for threatening speech under the Constitution.

"The jury was instructed that the government need prove only that a reasonable person would regard Elonis' communications as threats, and that was error," Roberts said. "Federal criminal liability generally does not turn solely on the results of an act without considering the defendant's mental state."

The high court's ruling means Elonis' case will return to a lower court, where a judge is expected to determine whether the plaintiff meant what he posted or acted recklessly in posting the messages. If that court decides the threats were real or that he knew better than to post them, Elonis' original conviction could stand.

After his wife, Tara, left him and took their two children, Elonis lost his job at an Allentown, Pennsylvania, amusement park and began posting a series of dark messages to Facebook five years ago. The posts contained threats of violence against Tara, his co-workers, kindergartners, police officers and federal authorities.

At times, Elonis used vulgar rap lyrics in his threats and claimed it was his First Amendment right to say what he felt. His lawyers argued that his postings were a form of therapy and art. He was convicted on four counts of transmitting threats. Elonis was sentenced to 44 months in prison and completed the term one year ago, according to the USA Today report.