Flickr / Wicker Paradise The smiley face, heart, praying hands and other emojis have become the way millions of internet users playfully punctuate their texts, posts, and messages, but for one middle schooler the icons brought the police to her door.

The 12-year-old from Fairfax, Virginia, has been charged with threatening her school after the police said she posted a message on Instagram in December laden with gun, bomb, and knife emojis. It read in part:

Killing 🔫

"meet me in the library Tuesday"

🔫🔪💣

As emojis and their relative the emoticon have rocketed from web slang to the unofficial language of the internet age, the case is one of a growing number in which authorities contend the cartoonish symbols have been used to stalk, harass, threaten, or defame people. And that has left the police and the courts wrestling with how to treat a newly popular idiom many still dimly grasp.

A grand jury in New York City recently had to decide whether 👮 🔫 represented a true threat to police officers. A Michigan judge was asked to interpret the meaning of a face with a tongue sticking out: :P. Emojis even took a turn in the Supreme Court last year in a high-profile case over what constituted a threat.

Such thorny questions are likely to only increase with the recent announcement that Facebook was rolling out a series of five face emojis users can select to react to posts in lieu of its ubiquitous "like" button.

"Emoji are new enough that people are finding their footing," said Tyler Schnoebelen, a linguist and founder of a company called Idibon. "Almost all of these cases have emerged in the past couple years. They are all going into fresh legal territory."

Emojis are icons of faces, hand gestures, fruits, animals, and other items that can be embedded in text. They are often used to indicate the tone of a message, add emphasis or are shorthand for things or ideas.

Emojis shot to popularity in the United States after Apple included an emoji keyboard on its iPhone in 2011. The advertising company Swyft Media estimates that 6 billion emojis and other pictograms are sent each day, and a report by an internet startup Emogi found that 92% of the online population used the icons.

That rise has led to challenges.

Flickr/Casey Fleser

The police are trying to judge just how serious to take threatening messages using emojis, which are most often deployed in a lighthearted manner. Attorneys have argued over whether emojis should be presented to juries as evidence. Experts say the biggest problem is simply determining in court what a defendant actually intended by sending a particular emoji.

Is a winkie face ironic, flirtatious, or menacing? What exactly do the popular dancing girl or grinning pile of poo emoji actually mean — if anything — when appended to a message? Emojis have no set definition, and their use can vary from user to user and context to context.

"You understand words in a particular way," said Dalia Topelson Ritvo, assistant director of the Cyber Law clinic at Harvard Law School. "It's challenging with symbols and images to unravel that."

Ritvo said some of these issues would most likely play out in the Fairfax case.

It began on December 14, when a resource officer at Sidney Lanier Middle School in Fairfax was made aware of the threatening Instagram post and others, according to a search warrant.

The officer began interviewing students and sent an emergency request to obtain the IP address of the user associated with the Instagram account. The investigation led to the 12-year-old, who was also a student at Lanier. The Post generally does not name juveniles accused of crimes.

The search warrant states the girl admitted to authorities she posted the messages on Instagram and did it under the name of another student. She was charged with threatening the school and computer harassment. A spokesman for Fairfax County schools said the alleged threat was deemed "not credible."

The girl is scheduled to make her first appearance in juvenile court on the charges at the end of the month. Authorities have not released a motive in the case, but the girl's mother said the girl posted the messages in response to being bullied at school.

"She's a good kid. She's never been in trouble before," the woman said. "I don't think it's a case where there should have been charges."

She's a good kid. She's never been in trouble before.

Ritvo said the girl's message sounded threatening, but prosecutors and the judge will have to sort out whether the bomb, gun, and knife emojis indicated a desire to threaten the school, simply anger, or something else entirely.

Other cases have run aground on similar distinctions.

Last year, a New York City teen was charged with making a terrorist threat after posting a message on Facebook that read "N--a run up on me, he gunna get blown down" followed by a police officer emoji and three gun emojis pointed at the icon's head.

A grand jury later declined to indict Osiris Aristy, 17, on the charge, and his attorney said the case was one of overreach by law enforcement. Fred Pratt said he's seen other clients use emojis the same way.

"I think something is definitely lost in translation," Pratt said of the police interpreting the teens' emoji use. "These kids are not threatening cops — they are just trying to say, 'I'm tough.' It's posturing."

Other cases have brought up an even more basic question: Should emojis even be considered as evidence?

A strange scene played out last year in New York City at the federal trial of the man accused of running the online drug market Silk Road. As a prosecutor began reading an internet post to the court, Ross W. Ulbricht's attorney raised an objection.

Ulbricht's attorney said the prosecutor had omitted mention of a smiley face emoji that punctuated and imparted meaning to a sentence. Afterward, the judge instructed the jury to take note of the emojis in the posts, saying they were part of the evidence.

Even so, there is still no set protocol in the courts for how — or even if — they should be presented to juries. It's an issue that the legal system will most likely be sorting through in the years to come.

Flying the shrug emoji proudly. Flickr / Topher McCulloch

In some cases, judges have been asked to interpret the meaning of emojis and emoticons (relatives of emojis made with traditional keyboard characters), including the Supreme Court. Anthony Elonis, a Pennsylvania man, argued that his conviction for threatening his estranged wife via Facebook should be overturned in a case decided last year.

Elonis, in the persona of a rapper, posted graphically violent lyrics on Facebook about killing his wife. His wife said she interpreted the posts as threats, but Elonis argued they were fictitious.

He indicated in some posts the lyrics were art or therapy. In others, he followed posts with the emoticon (a relative of the emoji) of a face with its tongue sticking out: :P. Elonis argued the pictograms proved the posts were jests.

The justices ultimately sided with Elonis and tossed out his conviction, in a ruling that made it harder to prosecute people for threats made on the internet. Emojis are likely to get close scrutiny when they pop up in similar cases going forward.

Bradley S. Shear, a Maryland attorney who specializes in internet issues, said the issues surrounding emojis and the legal system would only proliferate.

"These cases are only increasing," Shear said. "The more people are using their cellphones and posting on the internet, the more emoji will creep up as evidence in cases."

And that could leave judges wanting to type: ¯\_(ツ)_/¯

This article was written by Justin Jouvenal from The Washington Post and was legally licensed through the NewsCred publisher network.