Under the law, words can kill.
In convicting 20-year-old Michelle Carter of involuntary manslaughter for encouraging her boyfriend to commit suicide, Judge Lawrence Moniz cited what Carter told Conrad Roy III on the phone at the critical moment, after he had stepped out of a truck filling with deadly carbon monoxide: Get back in.
And the judge also listed words Carter did not say. She did not tell Roy to step out and save himself. She did not tell the police that a teenager was dying. She did not tell Roy’s family.
“At a critical point in time, the words spoken determined life or death,” said Timothy M. Burke, a Needham defense lawyer and former Suffolk County prosecutor who followed the case. “By her instructing him — given the nature of their relationship — to get back in the truck, it clearly presented the potential for a known risk of death.”
The case had been closely watched in the legal community for its potential to set precedent: Could a person be convicted of manslaughter on the basis of words alone? Now, in the eyes of some legal specialists, it could have far-reaching implications for what constitutes culpability.
The case was not a traditional involuntary manslaughter case, Burke said, because Carter was miles away from Roy when he died.
“But the law isn’t static,” he said. “And under these circumstances, her words did contribute in a significant way to his death.”
Moniz, who deliberated for two days before reaching his verdict, said the case was not legally novel since a Massachusetts inmate was prosecuted in 1816 — but acquitted — for persuading a man facing the death sentence to hang himself in his cell before he was executed. The judge also cited the prosecution of squatters who accidentally started a fire inside the Cold Storage warehouse in 1999 that killed six Worcester firefighters, for not alerting emergency personnel about the blaze.
Still, by convicting Carter in the jury-waived trial, Moniz surprised defense lawyer Brad Bailey, who watched the verdict announced live on television Friday morning.
Bailey said he disagreed that the evidence established that Carter’s actions were a direct and proximate cause of Roy’s death, and said the verdict creates a need for the state Legislature to step into the thorny issue of assisted suicide and clarify what conduct is legal.
“For those of us on the defense side, this is a surprising result,” said Bailey. “Many will agree this needs legislative clarification or this is going to remain a confusing area.”
State law does not specifically ban encouraging another person to commit suicide. Carter was accused of involuntary manslaughter based on conduct prosecutors said was reckless and likely to cause substantial harm. Roy, 18, poisoned himself with carbon monoxide in July 2014.
Martin W. Healy, chief legal counsel to the Massachusetts Bar Association, said that “the verdict represents the application of centuries-old common law principles and the interplay with today’s widespread use of communication through social media.”
He predicted the case will have national implications, demonstrating “that seemingly remote and distant communications will not insulate individuals from heinous acts that could rise to the level of criminal culpability.”
“The defendant’s fate was sealed through the use of her own words,” Healy said. “The communications illustrated a deeply troubled defendant whose actions rose to the level of wanton and reckless disregard for the life of the victim.”
Matthew Segal, legal director at the ACLU of Massachusetts, said in a statement after the verdict that Roy’s death was a tragedy, “but it is not a reason to stretch the boundaries of our criminal laws or abandon the protections of our Constitution.
“There is no law in Massachusetts making it a crime to encourage someone, or even to persuade someone, to commit suicide,” Segal said. “Yet Ms. Carter has now been convicted of manslaughter, based on the prosecution’s theory that, as a 17-year-old girl, she literally killed Mr. Roy with her words.
“This conviction exceeds the limits of our criminal laws and violates free speech protections guaranteed by the Massachusetts and US Constitutions.”
Segal suggested the verdict, if upheld on appeal, could chill “important and worthwhile end-of-life discussions between loved [ones] across the Commonwealth.”
Carter’s defense lawyers argued in court that Roy was a troubled teen who had attempted suicide multiple times. Carter had tried to help Roy by sending information on hospitals and mental health services, they said.
“The evidence presented reveals that the decedent alone provided himself with the means to kill himself and placed himself in a life-threatening situation,” the defense team wrote in a court motion. “Ultimately, his long-term thoughts, planning and acts toward the commission of his suicide were all of his own volition and creation.”
Prosecutors had alleged Carter was criminally reckless because she was on a cellphone listening as Roy, of Mattapoisett, succumbed to carbon monoxide fumes in his truck in Fairhaven.
Carter, who faces up to 20 years in prison, is scheduled for sentencing on Aug. 3.
Dorchester defense lawyer Michael Doolin anticipates “a lot of the issues in this case are going to end up getting resolved in either the Court of Appeals or the [Supreme Judicial Court]. And potentially in the federal courts, up to and including the Supreme Court.”
Doolin said he would not second-guess Carter’s decision to forgo a jury trial, due to the unique nature of the case.
“A lot of times when there are significant legal issues such as this, or you have a unique set of facts that in my opinion the law hasn’t entirely dealt with until this time, you want to go in front of a judge,” he said. “It takes emotion out of it when you’re appealing with a judge as opposed to a jury.”
The state Supreme Judicial Court ruled last summer that a grand jury had probable cause to indict Carter, determining that she was “personally aware that her conduct was both reprehensible and punishable.” It was the first time the court ruled that an involuntary manslaughter indictment could stand on “the basis of words alone.” The court found that through a stream of text messages and cellphone calls, Carter had established a “virtual presence at the time of the suicide.”
Rosanna Cavallaro, a law professor at Suffolk University, said the Supreme Judicial Court had “cleared the way” for the conviction by allowing the indictment to stand. Once the SJC said words alone could be considered as the cause of a death, “it’s hard to imagine a stronger case than this.”
Globe staff writers John R. Ellement, Jan Ransom and Travis Andersen contributed to this report. Mark Arsenault can be reached at email@example.com. Follow him on Twitter @bostonglobemark.