The teen is facing charges of possessing and distributing child pornography and uttering threats in the case.
It is believed to be the first time in Canada a teenager has been tried for pornography offences related to so-called "sexting."
The case has all the hallmarks of a modern-day teenage drama: a jealous new girlfriend, intimate photos of her boyfriend's former girlfriend and text messaging.
The Crown says the girl, who cannot be publicly identified because of her age, sent nude photos of her boyfriend's former girlfriend to another friend and to the ex-girlfriend. The Crown also alleges that the accused made threats in text messages to the ex-girlfriend in November of 2012.
Thousands of text messages examined
The one day trial on Thursday focused on 36,000 text messages and 4,000 images that were alleged shared among the accused, her friend, the boyfriend and the alleged victim.
The Crown argued it's clear the accused possessed and distributed child pornography. But defence lawyer Christopher Mackie says there is reasonable doubt about who did what.
"Any case of this nature, when we get into these technologies, it does become very difficult to trace who's sending what and how do we know, ultimately, who sent what? So that's part of the burden the court has is to try to figure that out."
And Mackie also questions the Crown's decision to only charge his client.
"There seems to be a number of people involved, but there has been only one person charged with any offence."
Furthermore Mackie says if his client is found guilty, he will launch a constitutional challenge, arguing his client should not have been charged because she is not a pedophile.