In a series of recent cases, emoji use has been interpreted by courts as constituting threatening behaviour, harassment and even defamation.

In part because of their immediacy in texts and online messaging, emojis "raise some of the most troubling cases", Deakin University professor of law, Marilyn McMahon, tells ABC RN's Law Report.

Professor McMahon says those charged with criminal offences involving emojis often claim they were "just joking" but this doesn't generally bode well in court.

"Their defence is typically unsuccessful," she says.

So what do courts consider when making decisions about emoji use — and what constitutes crossing the line?

Violent emoji use:

Professor McMahon says in the US, children as young as 12 have been charged after posting threatening messages online using bomb or knife emojis.

"The issue has been to interpret whether it is a serious threat that has been uttered by the young person, or whether it's, if you like, just letting off steam," she says.

In 2016, a 12-year-old student from Virginia was charged with threatening her school after the student posted a gun, bomb and knife emoji on Instagram, along with the words "killing" and "meet me in the library".

In other jurisdictions, emoji use has led to domestic violence charges.

Also in 2016, a 22-year-old man in France was sentenced to three months in prison after he sent his ex-girlfriend a series of text messages accompanied by a gun emoji, which was found to have constituted threatening behaviour. 

"The court concluded that it was clearly evidence of a death threat, the gun itself being evidence of the severity of the threat," Professor McMahon says.

In New Zealand, a man made threats in 2017 to his ex-partner accompanied by an emoji of an aeroplane.

The man and his ex-partner lived at opposite ends of the country, and the emoji was determined by the court to have "exacerbated" and "add[ed] to the immediacy" of a threat he'd issued to her — "that he was going to get on that plane and come and give effect to the threat", Professor McMahon says.

A costly thumbs-up:

Earlier this year, a Canadian judge ruled that the thumbs-up emoji could be as legally binding as a signature. 

The judge, in the province of Saskatchewan, ordered farmer Chris Achter to pay $82,000 ($AU90,000) for breach of contract, determining that he'd consented to it with a thumbs-up emoji.

Because there was a history of Achter using "curt words" – for example, "looks good" or "OK" – to consent to previous contracts via text, the judge ruled that the emoji had the same effect legally, and that there was a binding contract in place.

In another case in the US, which is ongoing, a full moon emoji has caused trouble.

"When people are hyping [promoting] stocks, they say that the stock is going to go 'to the moon'," explains Eric Goldman, co-director at the High Tech Law Institute at Santa Clara University.

So when billionaire investor Ryan Cohen tweeted about a company in which he owned stocks, and accompanied it with a full moon emoji, it was argued he was promoting that company's stocks, "in preparation for selling off his stake", as the Washington Post reported.

The judge commented that "emojis may be actionable if they communicate an idea that would otherwise be actionable".

"A fraudster may not escape liability simply because he used an emoji," Judge Trevor McFadden said.

It's being argued that using the emoji was a covert signal that people should buy that stock, which could constitute insider trading.

"That's another example of an area where a single emoji can cause potentially serious legal consequences, in that case, potentially securities fraud," Professor Goldman says.

Could it happen here?

Andrew Rich, an employment lawyer with Slater and Gordon law firm, says while it hasn't happened yet, a case such as the Canadian "thumbs-up" case could happen in Australia.

"[The case] has some relevance in Australia insofar as it may be used here to have some persuasive value.

"So you can imagine lawyers for a [client] raising it here and saying, 'Look what's happened in Canada, the court here should adopt the same approach'. It's not novel anymore," Mr Rich says.

He also says he's seeing more and more businesses communicate using emojis, particularly in the construction industry.

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Itchy underpants and Australia's consumer laws:

"These sorts of communications are on the rise.

"I'm talking about tradies, principally, [communicating] about the length of time for which they'll be engaged and the terms and conditions of their engagement."

Mr Rich says often there's "an ongoing back and forth" between contractor and employer about contracts, "sometimes involving emojis [and] text messages".

His advice? "Be careful."

"Really, it's a matter of being on your guard. And being careful in your communications and not responding before you've thought about what the effect of your response might be," he says.

But Professor Goldman believes the risk of a legal problem around emoji use is still "pretty low in most circumstances".

"More importantly, there are many circumstances in which emojis are actually the best way to express a person's thoughts or feelings."

Clarity, he says, is key.

"I encourage people to speak with as much precision as they can."

Original Story By | Sophie Kesteven & Damien Carrick