BOSTON, Mass. (WLNE) -- The Massachusetts Supreme Court heard arguments today on whether or not to uphold Michelle Carter's involuntary manslaughter charge. The Plainville teen was convicted last year after a judge decided she had encouraged her boyfriend to kill himself and was responsible for what he did.

Michelle Carter was sentenced to 15 months in jail but nearly a year and a half later, she still hasn't seen the inside of a jail cell.

Her lawyers today arguing against what the judge hinged his decision on, a text message sent to a friend months after Conrod Roy's death.

The highest court in Massachusetts is taking on Michelle Carter’s appeal. Judge Lawrence Moniz found her guilty. His decision was hinged on a text message Carter sent a friend, claiming Roy had called her during his suicide attempt and she told him to get back in the truck. Her defense saying the text is an unfounded confession.

"We have no idea what was said on those phones calls. An hour and a half where we have no window into what happened, what Conrad really did or what Michelle may have said,” says one of her lawyers Daniel Marx

Conrad Roy died of carbon monoxide poisoning after starting a generator inside of his truck in July 2014. Judge Moniz also said Carter had a duty to call 911 knowing the situation he was in. The Commonwealth arguing today she coerced him and knew he would do what she told him to.

"Legally if you see a person in peril and you didn't do anything to put them in that perilous situation, you don't have a duty to rescue,” says Hillary Farber, a Law Professor at UMass Dartmouth.

Farber says this appeal has the power to change the landscape.

"It’s significant, taking physical presence and physical assistance out of the equation and saying words matter here and words alone can constitute the kind of wanton and reckless conduct the government proved here,” says Farber.

It could be months before the SJC announces its decision.

© WLNE/ABC 6 2018