CONCORD, N.H. – Even though talking on a cellphone while driving is not illegal in New Hampshire, the Supreme Court says doing it can be used to convict a driver of criminally negligent homicide.

In its unanimous ruling Friday, the court upheld the conviction of Lynne Dion of Franklin in the 2009 death of pedestrian Genny Bassett.

Phone records showed Dion used her cellphone to call a friend 90 seconds before using that same phone to call police after the crash.

Dion’s lawyer, Allison Ambrose, argued in her brief that because cellphone use while driving is legal, it is not enough to convict someone of criminally negligent homicide.

“For that conduct to be blameworthy there’s going to have to be some change in the law,” Ambrose said. “That’s not for the jury or the court to decide.”

The five justices of the state’s highest court disagreed.

“Conduct that is, itself, not prohibited — including the use of a cellphone while driving — may constitute the requisite blameworthy conduct when such use results in inattention and distraction,” Justice Carol Ann Conboy wrote.

The case marks the first time the court addressed cellphone use in the context of a criminally negligent homicide conviction.

To find Dion guilty of criminally negligent homicide, the state had to prove beyond a reasonable doubt that her conduct amounted to a “gross deviation from the conduct that a reasonable person would observe in the situation.”

Dion, 48, was sentenced in 2011 to 18 months to three years in prison and her license was revoked for seven years from the date she is released from prison. She has remained free on appeal.

Bassett left her home to walk home her close friend, 60-year-old Elsa Gonnella, after an evening of playing cards and watching movies. The two women were crossing a bridge in Franklin and had almost reached the sidewalk when they were struck by Dion’s car at about 9 p.m. on June 28, 2009.

Dion said she never saw the women in the freshly painted, well-lit crosswalk. Dion braked when she heard a loud pop and glass showered into her car. Her vehicle had hit Bassett’s right leg and Bassett’s head hit the passenger side of the windshield, fracturing her skull and causing a fatal head injury. Gonnella was knocked to the ground and temporarily lost consciousness.

The court on appeal also rejected Dion’s assertion that phone records of her half-dozen calls during the 37-minute drive from a friend’s house in Sutton to the time of the accident should have been excluded, saying they were introduced to outrage the jury and confuse the issues.

The court ruled the records of the calls “bore directly on the issue of the defendant’s inattentiveness in the minutes leading up to the collision.”

Senior Assistant Attorney General Susan McGinnis, who argued the case for the state, said she hopes the decision sends the message that driving while talking on a cellphone is “incredibly dangerous.”

“When someone does something dangerous who appears to not be paying attention, invariably they’re on a cellphone,” said McGinnis, who said she was almost hit the other day by someone who ran a red light while talking on a phone.

McGinnis said she was also gratified that the Supreme Court elected to hear the arguments at Monadnock Regional High School, as part of its “On the Road” series to heighten awareness of the court’s role. “Hopefully they get the idea that they could kill someone,” she said.

Ambrose did not immediately return a call seeking comment.