BOSTON (Reuters) - A Massachusetts woman could be sentenced to up to 20 years in prison this week for sending text messages to her boyfriend urging him to commit suicide. The verdict was the first of its kind in the state, and legal experts said it is likely to be appealed.

Michelle Carter, now 20, was found guilty in June of involuntary manslaughter for the messages she sent to her 18-year-old boyfriend, who asphyxiated himself in his parked truck as she texted him in 2014.

Child welfare advocates said the case illustrated serious concerns about cyberbullying, while free-speech proponents said Bristol County Juvenile Court Judge Lawrence Moniz’s guilty verdict infringed on Carter’s free-speech rights by criminalizing her words.

Carter’s attorneys have not yet said if they plan to appeal the verdict, but legal experts said it could be vulnerable given its groundbreaking nature.

“As abhorrent and horrific as Michelle Carter’s behavior was, and it was appalling, I’m not sure it’s manslaughter,” said David Medwed, a professor of law and criminal justice at Northeastern University in Boston.

He said that for a manslaughter conviction one would need to prove the defendant directly caused the death and there could be an argument that even though she prodded him, it was ultimately the victim who made the decision.

Her boyfriend, Conrad Roy, had attempted to kill himself multiple times before succeeding in a parking lot about 60 miles (96 km) south of Boston. Carter, who like Roy had mental health problems, was about 30 miles (48 km) away at the time of his death.

The American Civil Liberties Union of Massachusetts has already criticized the ruling as a violation of Carter’s right to free speech. Massachusetts is one of about 10 U.S. states where it is not illegal to encourage suicide.

“While Mr. Roy’s death is truly devastating, it is not a reason to stretch the boundaries of our criminal laws or abandon the protections of our constitution,” said Matthew Segal, the group’s legal director.

Carter’s attorneys argued she had been involuntarily intoxicated by medication and not fully able to comprehend the consequences of her actions.

The length of Carter’s sentence will likely influence whether she appeals the verdict. That may tempt Moniz to impose a sentence of only probation to reduce the risk of an appeal, said Boston College law professor Robert Bloom.

“If I were the judge, that would be something that I would be thinking about,” Bloom said.