Michelle Carter listens as ADA Maryclare Flynn makes her opening statement, displaying many texts between Carter and Conrad Roy III, as the trial of Carter proceeds in Bristol County Superior Court in Taunton, MA on Jun. 6, 2017.

The U.S. Supreme Court said Monday it will not take up an appeal brought by Michelle Carter, the young woman who encouraged her boyfriend, through texts and phone calls, to commit suicide.

The court's refusal to take the case leaves her conviction intact.

The case attracted worldwide attention and was the subject of a 2019 HBO documentary, "I Love You, Now Die: The Commonwealth V. Michelle Carter."

The court declined to decide whether her involuntary manslaughter conviction violated the First Amendment guarantee of free speech because it was based solely on words that she texted or spoke. She was sentenced to 15 months in jail.

In July 2014, 18-year-old Conrad Roy III of Massachusetts parked his truck and filled it with carbon monoxide, killing himself after several failed suicide attempts.

Evidence at her trial showed that Carter, who was 50 miles away in Plainville, sent text messages in the days leading up to the suicide, encouraging him to go ahead with his plan, and spoke to him twice on the phone the day he took his own life.

She later told a friend that he became frightened at one point and climbed out of the truck but that she told him on the phone to get back in. The trial judge said that statement and her failure to call 911 or summon help, were key facts supporting her conviction.

Her lawyers told the Supreme Court that she could not be convicted based solely on the words she texted or spoke – or failed to text or speak. "Carter neither provided Roy with the means of his death nor physically participated in his suicide." They said the Massachusetts courts provided no guidance on how to determine when a person's words cross the line and become criminal conduct.

Prosecutors said that after at first trying to discourage him from suicide, Carter began a systematic campaign of coercion, prettying on Roy's insecurities. She taunted him that he would purposely fail again to kill himself, repeatedly urging him that he "just [had] to do it" and that "the time [was] right."

Her conviction, the state said, was consistent with a long established exception to the First Amendment for "speech integral to criminal conduct."