Should courts care what Anthony Elonis really meant when he said on Facebook that he wanted to make his wife a bloody corpse?

Free speech makes strange bedfellows. On Monday, civil liberties groups, anti-abortion lobbyists, rap scholars and animal rights groups will get their chance to press their case in the supreme court, in a case brought by a convicted criminal who threatened to kill his wife.

Anthony Elonis, a former Pennsylvania amusement park worker, was convicted in 2011 of threatening to kill his wife, shoot children at a kindergarten and slit the throat of an FBI agent. The threats were made on Facebook and raise one of the central questions of the digital era: when do threatening comments made online cross the line into criminal activity?

“Did you know that it’s illegal for me to say I want to kill my wife?” he wrote in one of many posts. “It’s illegal. It’s indirect criminal contempt. It’s one of the only sentences that I’m not allowed to say.”

In another post, he wrote: “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 he made threats to his former employer, Dorney Park, an FBI agent visited him at home. This prompted Elonis to write: “Little agent lady stood so close, took all the strength I had not to turn the bitch ghost. Pull my knife, flick my wrist and slit her throat.”

Elwood used a rapper-sounding pseudonym, Tone Dougie, on Facebook for posts and made references to his “art” and first amendment speech rights as well as using smiley faces to indicate some threats were “jokes”.

His lawyers contend he never intended actual violence and was merely sounding off during a dark period of his life. After two lower courts upheld his conviction the supreme court is being asked to decide whether Elonis’s state of mind matters, as long as a “reasonable person” would feel threatened.

The supreme court last looked at this issue in 2003, in Virginia v Black. In that case the court ruled that a Virginia law went too far in ruling that cross-burning, long associated with the Klu Klux Klan, was “prima facie evidence of an intent to intimidate a person or group”. The court ruled that not all cross-burning was meant as a threat but that it could be seen as a criminal offence if the intent to intimidate was proven.

The ruling was made in a world before Facebook or Twitter, let alone trolling. The National Network to End Domestic Violence (NNEDV) and other victim support groups are warning the court that they must address an epidemic of online abuse that has risen in the interregnum and need to protect people from the “devastating psychological and economic effects of threats of violence, which their abusers deliver more and more often via social media”.

“A standard that requires proof of the speaker’s subjective intent – what he ‘really’ intended in his heart of hearts – for conviction of threatening another person would fail to protect victims of intimate partner violence and stalking from the real and predictable harm caused by the threats of violence they face daily,” the NNEDV wrote in its brief to the court.

The Elonis case comes after the supreme court declined to hear a similar case last year. In that case Franklin Delano Jeffries II, a man convicted of threatening to kill the judge in his child custody case, also used Facebook to make threats. Jeffries recorded a song, called Daughter Love, and uploaded it to YouTube and Facebook. The song contained the lines: “’Cause if I have to kill a judge or a lawyer or a woman I don’t care. ’Cause this is my daughter we’re talking about” and “Take my child and I’ll take your life.”

Depending on their decision, the justices could redefine the way threats of online violence are treated. The justices will decide to what extent, if any, they want to redefine “subjective” and “objective” intents to threaten violence in a digital age.

The subjective intent argument takes into account what the person was thinking and the context of the threat – whether they actually meant to carry it out. Elonis was convicted on an “objective” definition of intent with the court ruling that “a reasonable speaker would foresee the statement would be interpreted as a threat”. But the law remains a battleground and the supreme court has to date avoided adding clarity.

Lee Rowland, a staff attorney with the American Civil Liberties Union’s speech, privacy and technology project, believes the law as it stands can adequately deal with the challenges the internet creates for free speech and the protection of people from actual threats.

“In reality prosecutors tend to use the criminal law against folks we think of as bad guys, people who are intending to do harm and who actually do harm,” she said. “I don’t think many people are arguing that juries should have the right to put people in jail for making a mistake or for uttering something that’s out of context, or for making a statement that someone believes is threatening when it isn’t.”

She said “subjective” intent was not a “get out of jail card”. “The subjective intent requirement gives the speaker the opportunity to explain that their comment was innocent or to explain the context that it was not a threat. With that in place a jury can do what a jury always does and assess the credibility of the witness’s account,” she said.

Rowland highlighted that Elonis was found guilty on all charges except one – a threat to his former employer that was capped by a smiley face – and that a subjective definition of intent could have arrived at the same verdict.

“The legal standard should unquestionably be the same whether speech occurs online or offline,” she said. Nuance and sarcasm do not always play as well online as in real life and with that in mind she said the subjective intent argument applies with “equal if not greater force”.

But for victims’ groups the harm is created by the threat itself. “Requiring the government to prove beyond a reasonable doubt that the speaker subjectively intended to convey a threat (and did not have some other private purpose) is not adequate to the task of protecting people from the harms threats of violence cause,” the NNDV has told the court.

“Such a rule would leave too many victims of threats without any meaningful protection. It would also effectively decriminalise conduct that predictably and reasonably creates a genuine fear of violence with all its attendant psychological, emotional, economic, and social disruptions.”