Massachusetts' top court ruled Friday that a teenager may stand trial on involuntary manslaughter charges in connection to text messages she sent urging her friend to commit suicide.

In a unanimous ruling, the Supreme Judicial Court said a local grand jury had enough probable cause to indict Michelle Carter in connection to the 2014 suicide of Conrad Roy, who was found dead about 50 miles south of Boston in a Fairhaven parking lot. Carter was 17 at the time of Roy's suicide, and she is accused of sending Roy several texts, including one saying "get back in" the day the 18-year-old teen took his own life via carbon monoxide fumes inside his truck.

The defendant's lawyers maintained that her texts were constitutionally protected speech under the First Amendment. The court, however, did not create a bright line rule on where free speech ends and criminality begins. Instead, the court ruled that a physical act of violence is not necessary to sustain involuntary manslaughter charges and that each case is "entirely fact specific."

"We have never required in the return of an indictment for involuntary manslaughter that a defendant commit a physical act in perpetrating a victim’s death,” the court ruled. (PDF) "We also never have had occasion to consider such an indictment against a defendant on the basis of words alone."

Defense attorney Dana Curhan agreed with the top court that it was a case of first impression. But Curhan said the girl "did not coerce him" because suicide "was what he had planned to do."

The court ruled that there were some telephone calls, too, and that the girl was at least virtually present at the suicide during “those final moments, when the victim had gotten out of his truck, expressing doubts about killing himself.”

The constant communication "during the suicide," the court noted, "made the defendant's presence at least virtual."

The court said that the girl's "coercive" messages "overwhelmed whatever willpower the eighteen-year-old victim had to cope with his depression, and that but for the defendant's admonishments, pressure, and instructions, the victim would not have gotten back into the truck and poisoned himself to death."

One text message read, "I thought you wanted to do this. The time is right and you're ready, you just need to do it!" Another said, "You can't think about it. You just have to do it." Another text said, "You said you were gonna do it. Like I don't get why you aren't."

"There is a point that comes where there isn’t anything anyone can do to save you, not even yourself," one text read.

No trial date has been set. If convicted, the minimum penalty is 40 months of prison. The maximum is 120 months.