Image copyright CBS Image caption Carter on Friday waiting to hear if the judge would dismiss her case

A judge has refused a bid to dismiss the case against a woman accused of driving her boyfriend to suicide.

Defence lawyers said Michelle Carter's actions were "reckless", but did not rise to the level of criminality.

The 20-year-old is charged with involuntary manslaughter for calling and texting 18-year-old Conrad Roy, urging him to take his own life.

The prosecution rested its case on Thursday, saying her texts amounted to: "I love you. Kill yourself."

Ms Carter's lawyer, Joseph Cataldo, argued on Friday that the state could not prove she caused Mr Roy's death.

Image copyright ABC Image caption Mr Roy was found dead in his pickup truck in July 2014

The attorney asked Bristol Juvenile Court Judge Lawrence Moniz to dismiss the case, citing a lack of "causation", but the judge disagreed.

Prosecutor Katie Rayburn argued the causation came when Ms Carter told Mr Roy during a 46-minute phone conversation on the night of his death to "get back in the car", as it was filling with poisonous carbon monoxide gas.

Ms Rayburn claimed that in the 20 minutes it took for Mr Roy to die, the accused could have sought emergency help.

Mr Roy was found dead in his pickup truck in a K-Mart car park on 12 July 2014.

On his phone were multiple messages from Ms Carter, including one saying: "You're so hesitant because you keep over thinking it and keep pushing it off. You just need to do it, Conrad."

"Hang yourself, jump off a building, stab yourself I don't know there's a lot of ways," she said in several messages sent in the two weeks before his death, as he was on holiday with his family.

Image copyright Facebook Image caption Ms Carter reportedly texted Mr Roy that his parents would "get over" his suicide

Ms Rayburn also argued on Friday that Ms Carter, who was 17 years old at the time, took advantage of Mr Roy's struggles with depression and attempted to "isolate" him from his family.

Video journals documented by Mr Roy have been shown to the court.

He often discussed his "social anxiety", but at other times expressed hope for his future and job prospects.

"I just got a job from the Boston Duck Tours to captain their boat," Mr Roy said into his home computer's camera. "Like that's a huge accomplishment."

The prosecution said Ms Carter urged Mr Roy to kill himself in order to get attention as "the grieving girlfriend".

But Mr Cataldo reminded the judge, who will be determining the verdict after Ms Carter opted to forgo a jury trial, that Massachusetts is one of about 10 states that do not criminalise assisted suicide.

Her lawyers have argued that her words fall under free speech, protected by the first amendment of the US constitution.

On Thursday, friends of Ms Carter testified about their conversations with her in the days after Mr Roy's death.

In one text to a friend, Ms Carter wrote: "Sam, [the victim's] death is my fault like honestly I could have stopped him I was on the phone with him and he got out of the [truck] because it was working and he got scared and I f****** told him to get back in Sam because I knew he would do it all over again the next day and I couldnt have him live the way he was living anymore I couldnt do it I wouldnt let him."

Another message to her friend, Alexandra Eitheir, stated: "I was on the phone talking to him when he killed himself. I heard him dying."

She also contacted a friend when she learned that investigators were looking through Mr Roy's phone.

"They read my text messages to him I'm done", the accused wrote, adding, "his family will hate me and I could go to jail".

Where to get help

If you are depressed and need to ask for help, there's advice on who to contact at BBC Advice.

From Canada or US: If you're in an emergency, please call 911. If you or someone you know is suffering with mental-health issues, call Kids Help Phone at 1-800-668-6868. If you're in the US, you can text HOME to 741741

From UK: Call Samaritans on 116123 or Childline on 0800 1111