The U.S. Supreme Court said Monday that it will not consider an appeal by Michelle Carter, the Massachusetts woman who was sentenced to 15 months in prison for relentlessly pressuring her then-boyfriend in text messages to kill himself.

Carter, who was convicted of involuntary manslaughter in the 2014 death of 18-year-old Conrad Roy, had argued that her actions were a matter of free speech protected by the First Amendment.

A series of text messages sent between the couple on the night Roy died showed Carter, then 17, repeatedly urging a suicidal Roy to kill himself by carbon monoxide poisoning in his truck, even after he told her he no longer wanted to go through with it.

Boston Globe via Getty Images Michelle Carter, seen during her trial, was convicted of involuntary manslaughter for encouraging 18-year-old Conrad Roy III to kill himself in July 2014.

“You always say you’re gonna do it, but you never do,” she said in one text to him after he expressed hesitation, according to arrest documents. “I just want to make sure tonight is the real thing.”

In a later conversation with a friend, Carter admitted that she ordered Roy in a phone call to get back into his vehicle when he became frightened and wanted to call it off.

“Instructing Mr. Roy to get back in the truck constituted wanton and reckless conduct,” a Bristol County Juvenile Court judge ruled in 2017.

Carter’s attorneys have continued to argue, however, that her words alone aren’t enough to blame for his death. In a statement to HuffPost on Tuesday, they said they are “deeply disappointed” with the court’s decision.

“The Court passed on the rare chance to clarify an outdated and confusing exception to the First Amendment, which has divided courts around the country,” said her attorney, Daniel N. Marx.

Massachusetts Attorney General Maura Healey, who argued against Carter’s petition for an appeal in November, echoed the previous court’s ruling in the case that wanton or reckless conduct that causes a person’s death constitutes involuntary manslaughter and that speech that’s integral to crime is not protected by the First Amendment.

“Inasmuch as petitioner’s wanton or reckless conduct causing Roy’s death was carried out by speech, that speech was therefore unprotected because it was integral to the commission of involuntary manslaughter,” Healey’s petition stated, while also calling Carter’s First Amendment conflict “illusory.”